industrial heating

VärmeKabelTeknik Industrial heating

from

Industrial heating VärmeKabelTeknik 2

Dimensioning guide

This manual contains all necessary information to dimension heating and frost protection of pipes, tanks and cisterns. You get help to choose cables and accessories for your application.

A dimensioning guide for pipe systems is also available on a 5 1/4" or 3 1/2" disk for PC (The programme requires only 512 KB).

The calculation programme is adapted so that you easily could feed the values which are required to project heating cable application and you obtain a complete material list after running.

Introduction

In order to be able to take out a correct solution for a heating cable application it is important to have some basic knowledge. It is the heating cables task to compensate for heatloss from the construction part through the thermal insulation and in some cases increase the temperature on the encased medium.

We also deliver an extensive assortment of heating products above heating cables. You will find these in our catalogue. Is there something you miss? Give a call to any of our offices and tell us about your needs and we help you in the best possible way to make a solution.


3

Chapter 1 Product overview Products for electrical heating on pipes and containers and other heat demanding applications

VÄRMEKABELTEKNIK have a complete assortment of heating cables adapted for various purposes from frost protection to heating with a supplementary product programme with heating system for the industry.

Värmekabeltekniks programme

• Parallel resistive heating cable with constant output.

• Self‐limiting heating cable

• Series resistive heating cable. PVC‐, Teflon and Mineral insulated, with or without return‐wire.

• Immersion heaters

• Heating foils made of polyester (80°C) Silicone (250°C)

• Nozzle heaters

• Ceramic infra heaters for contactless heating

• Surrounding equipment, control equipment, etc.

Our speciality

VärmeKabelTeknik have by its comprehensive knowledge and wide assortment the possibility to help to take out complete package solutions for special applications on products where heat supply is required.

We can also in certain cases assist with installing our heating products on the customers provided machine component, container, portable pipes, etc.

Contact us with your inquiry for a profitable suggestion.

Projecting guide

With this manual we want to give you information on the range of applications of our products.

The manual describes the characteristics of the products and gives you an insight in calculations of energy requirement for the most common applications.

In the following chapter you can also see how an application is calculated, dimensioned and which specifications required doing these calculations.

This help you to get out all information when you wants help of any of VärmeKabelTeknik s technicians or when you will prepare for your own calculation.

Värmekabeltekniks support

You can safely leave your drawings or verbal information on your application to our experienced sellers to get help with calculations and projecting and quotation on your object.

You will get a complete suggestion with material, specification and price on heating source, assistance at installation and control.

On request you obtain a installation instruction especially designed for your application and you can always give us a call if any questions occur during the work.

You can also get help with relation papers on the heating cable application and sketch of the heating cable installation on one by you provided drawing.

VärmeKabelTeknik can adapt heating products to your application or help you with apply heat on your portable instrument/equipment.

Series resistive heating cables The first heating cable that was produced was of a series resistive type. Today there are several types series resistive heating cable available. These are manufactured in qualities from PVC to mineral insulated high‐temperature cable with rustless sheath. The biggest advantage with these is the possibility to obtain long element lengths, from only one point of connection.

In contrary to parallel resistive and self‐limiting heating cables which maximum length are limited by the voltage drop in the conductors, this is used as a heat emitting part in a series resistive cable. The heating conductor is manufactured of an alloy that gives required resistance per meter. By combining a required length with the available cable resistance’s and supply voltages can advantages be obtained such as varying outputs, lengths from a couple of meter to lengths on 800‐1000m from one point of supply.


Chapter 1 Procut overview Products for electrical heating on pipes and containers and other heat demanding applications

Som nackdel kan ses att kabeln vanligtvis måste It is a disadvantage that the cable normally must be finished on the factory, which means you have to know the pipe lengths in advance to be able to pre order required lengths. (AT long high‐temperature lengths where the heating conductor contains copper (CC‐cables) shall consideration be taken to the temperature coefficient of the heating conductor which influence the output of the length negatively).

For installations within the EX‐surface a number of supplementary safety devices is required, and exemption from the touched authorities.

Constant wattage cables

Parallel resistive cables can be bought as running metre for making‐up on the site. This admits a good flexibility both at new production and repairs. The cable has a constant output per metre irrespective of length and temperature and can be cut on regular distances, most often between 0,5 ‐ 1,2 metres dependent on module lengths from different suppliers.

The heating element in a parallel resistive cable consists of a resistance wire which is coiled round the insulated front conductors, at the so called contact points (these have been marked as waist on the outer side of the cable) have the resistance wire contact against one of the conductors alternating for each contact point.

Heating cable of series resistive, mineral insulated type

The insulation material and the sheath consist normally of teflon material.

There is more detailed information in the cable date sheets.

The heating cable is designed with earth braid that also works as an armouring and corrosion protected sheath of teflon where this is not possible by high temperatures.

Parallel resistive heating cables gives a solid output per meter independent of the ambient temperature. They have no starting current and can therefore be connected in relatively long lengths, (se cable data).

Self- l imiting heating cables

Self‐limiting heating cables can be bought in running metre for make‐up on the site. The cable has a varying output depending on the ambient temperature, which guard against overheating even if the cables crosses itself. This also allows installation in Ex‐surfaces (all Värmekabeltekniks self‐limiting cable types are Ex‐rated).

The self‐limiting cable have a unique capacity in proportion to the sheath temperature of the cable, reduce the emitted output. These cables are often mentioned as self‐regulated cables but this is a wrong denomination, as a required temperature not can be guaranteed without temperature control.

On the other hand, the cables make it possible to give an even temperature on a pipe even if the ambient temperature varies along piping.

Värmekabeltekniks self‐limiting cables are approved within Ex‐surfaces when the cables have a stated T‐Rate, i.e. a maximum temperature that the cable reach. The T‐rates varies for different output/m.


5

Chapter 2 Range of application for heating cable/Other

Diagramme - load/temperature series resistive cables

VKT:s heating cable products characteristics - industrial cables

Mineral insulated cable

Features SRL SRM CWM Koppar Cu/Nickel Incoloy TCT TCTR

Max. maintenance temp.(°C) 85 150 120 200 300 450 160 160

Max. exposed temperature (°C) 130 180 200 250 350 600 200 200

Max. Wattage/m 33 65 30 Dependant on process temp Dependent on temp

Max circuit length See data sheet

See data sheet

See data sheet

Dependent on suply voltage Dependent on supply (U)

Votlage 120, 240 120, 240 240/440 1‐600V 1‐600V 1‐600V 1‐440V 1‐440V

Ex‐approved Yes Yes No No* No* No* No No

Usable on plastic pipes Yes No No* No** No** No** Depend. On power

Can be cut on site Yes Yes Yes No No No No No

Can cross itself Yes Yes No No No No No No

Varying output/temperature Yes Yes No No No No No No

Varying output along cable run Yes Yes No No No No No no

* The cables are Ex‐approved in a number of countries. At use in for example Sweden shall exemption be applied for. ** Suitability depend on load/metre


Chapter 2 Range of application for heating cable/Other

Maximum cable temperature

Heating cables has a limited max. temperature in consequence of the material which is used at their construction. If the temperature exceeds recommended values, the lifetime is shortened or at worst the cable is destroyed.

* Therefore find out which maximum temperature can arise in consequence of the process –where the heating cable application is included.

* Also find out if so called steam purifying occurs when steam can give temperatures up to approx. 200°C.

There are two different maximums:

A. Max. temperature when cable is switched on This information of max. temperature indicates the maximum temperature the cable could maintain. (Consideration should however be taken to the calculation of the sheath temperature on the previous page where the real temperature is related to the stated output of the cable).

B. Max. temperature when the cable is switched off This information mentions what the cable can handle when switched off at frost protection of for example steam conduit or heating of a heavy oil conduit where the operation temperature is considerable above the required heating temperature. Here the function is that one in the intake end of the pipe place the transmitter of the thermostat/regulator so that the supply voltage of the cable disconnects when the process exceeds the heating temperature.

The diagram shows a comparison of the maximum exposure temperature of our heating cable products, with the heating cable disconnected.


7

Chapter 2 Range of application for heating cable/Other TCT – Series resistive single‐wire

VELOX TCT Series resistive single wire is built‐up with a heating conductor of high‐temperature type. The heating conductor has an insulation of teflon material. On this an earth screen placed of tinned copper, which is covered by an outer layer of teflon. The heating cable can be exposed of temperatures up to 220°C and manages heating up to approx. 200°C depending on the load (see diagram on the data sheets).

The cable manages most of the chemical environments and is well suited for frost protection to heating of various objects.

The heating cable with its small dimensions (3‐3,5 mm) and its soft construction usable to the most applications.

The TCT is series resistive, which admits long heating lengths (approx.250m). This is an advantage at long pipings and minimises the number of connection points at all types of installations.

Example on common applications of TCT is asphalt work, oil pipes and filter bunkers. The heating cable shall always be connected via thermostat control.

TCTR – series resistive return wire

VELOX TCTR Series resistive heating cable with return wire which is built on a TCT, but with a further screen and layer of teflon. In this case the inner screen is used as a return wire and the outer as earth screen.

Max. ambient temperature is approx. 220°C. Max. ope‐ration temperature, approx. 190‐200°C.

This cable is especially suited for installation where long lengths are required and/or where it is hard or unpractical to return to the starting point.

Example where the TCTR gives an extra economical solution is a long pipe length where one cable run is enough.


Chapter 2 Range of application for heating cable/Other LMI – mineral insulated heating cable

Mineral insulated cables consist of a conductor of copper alternatively an alloy. The conductor insulation consists of a hard packed magnesium oxide (MgO). The cable is supplied with a solid‐drawn sheath of copper, copper/nickel or stainless steel, which also serves as an earth wire. The cable has a smaller diameter than other types of cables and is furthermore slightly flexible and can with no problems be installed in complicated cable runs. The cables are meant for applications with operating temperatures up to 200°C. Can be provided with a corrosion protected outer sheath.

The advantages with mineral insulated cables are many, below you’ll find some of them:

Flame‐resistant Värmekabeltekniks MI‐cable has a sheath of incombustible material. The most compact insulation prevents transfer of steam, gases and flames between equipment parts, which are connected through the cable. Bare cables emits no smoke or toxic gas and do not spread fire. When corrosion protection is required, the volume is very small which gives a reduced discharge of Halogen.

Waterproof Värmekabeltekniks MI‐cable has a seamless metallic sheath, which do not let water, oil or gas lose.

Corrosion‐proof Since the MI‐cable from VärmeKabelTeknik has a metallic sheath, it is also very corrosion‐proof and does not need extra protection when used in normal environments. If the cable is exposed to difficult chemicals, it can be protected with an outer sheath.

High operating temperatures Värmekabeltekniks MI‐cables manages continuous operating temperatures up to 600oC. The maximum continuous operating temperature at the corrosion protected cable is approx. 200oC (HDP). Other insulation material can be ordered specially. The most common is yet that the cable is installed without outer protected jacket.

Example on range of applications

Chemical industries

Heating of pipes and bearing tanks to keep the products at correct temperature during the processing.

Power stations

Electrical heating of pipes with fuel oil and to prevent the instruments from freezing during the winter.

Nuclear industry

Mineral insulated heating cables can be used within several ranges of applications in the nuclear industry. The are used to heat pipes, ventilators, cisterns and to preheat the sodium circuits of the reactor.

Dock yards

Frost protection cables to protect instrument and pipe bridges from ice formation.


9

Chapter 2 Range of application for heating cable/Other RSL‐CR‐CT–Self‐limiting heating cable

APPLICATION

SRL self‐limiting heating cable gives a reliable frost protection of pipes, ventilators, cisterns and similar applications. Max maintenance temperature 65°C (Exposure temperature, switched off 85°C)

Advantages:

• Approved for installation in Ex‐surfaces (T5‐T6)

• The heating cable can be crossed at installation (for example at ventilators) when the cable reduces its output at rising temperatures.

• Can be cut in required length and made‐up on the site. (Take consideration to the max. connection lengths stated in the data sheets).

• Outdo heating with steam. Lower installation costs and a more safe operation.

• Self‐limiting output makes over temperature impossible.

• Värmekabelteknik:s connection‐/end termination kits and connecting material with detailed descriptions is a good help at the installation.

RSM‐CR –Self‐limiting heating cable

APPLICATION

SRL self‐limiting heating cable gives a reliable frost protection of pipes, ventilators, cisterns and similar applications. Max maintenance temperature 65°C (Exposure temperature, switched off 85°C)

Advantages:

• Approved for installation in Ex‐surfaces (T5‐T6)

• The heating cable can be crossed at installation (for example at ventilators) when the cable reduces its output at rising temperatures.

• Can be cut in required length and made‐up on the site. (Take consideration to the max. connection lengths stated in the data sheets).

SRM can be cut and completed on site. (Take consideration to the maximum circuit length, see data sheet).

The cable can cross itself (for example at installations on ventilators) without risk of overheating.

Outdo heating with steam. Lower installation costs and maintenance cost than steam.

Self‐limited output makes overheating impossible.

Värmekabelteknik:s connection‐/end termination kits and connecting material with detailed descriptions is a good help at the installation.


Chapter 2 Range of application for heating cable/Other EST/CWM – parallel resistive heating cable

Parallel resistive heating cables with constant output/metre irrespective of length may very well be cut and completed on the site. Parallel resistive cables were introduced in Sweden on the 1970’s, but first during the 80’s the cables come into use in an increasing extent.

Cables of parallel resistive type have two conductors, which are separately insulated. Round these conductors, a NiCr‐wire is winded which are connected at regular intervals to the conductor, alternating so that each zone becomes –a separate element. The electric conductor of the parallel resistive cable is constructed by twisted, tinned copper braid.

Conductor areas from 1,5 mm² to 3,5 mm². The conductor insulation and the armouring bed is made out of teflon material.

The cable is braided of tinned copper wire as armouring/earth screen and a outer sheath of teflon material.

Parallel resistive heating cables are available in a number of different running metres/outputs. EST/CWM is meant for exposure temperatures up to 200°C (switched off) and could maintain pipe temperatures up to approx. 170°C (10W/m). The cable is installed with an aluminium tape or glass fibre tape for example, for attachment. For connection‐ and end termination is mounting kits used for cables of parallel resistive type. For more information, see data sheets.

The cables are complete simply by follow the instructions available in the mounting instructions step by step. Consideration should be taken to the recommended maximum connection lengths valid for the different outputs on the parallel resistive cables. Regarding the lengths, have consideration been taken to the voltage drop in the electric conductors of the cable and other technical data can be found in the data sheets.


11

Chapter 2 Range of application for heating cable/Other Other heating products for the industry

Heating foils of si l icone

Heating foils made of silicone are meant for applications where high outer temperatures are required. They are kept in stock in Sweden in a number of different sizes with outputs up to 1.5 W/cm² with operating temperatures on max 250°C.

On request can special shapes (element with hole patterns, built‐in thermostats etc) and outputs be delivered. However, a minimum of 25pcs must be ordered of special foils.

The heating foil is manufactured with a resistance wire, which is vulcanised in the middle of two silicone plates. The elements are installed with special glue, feather or screw unions and shall be temperature controlled by a thermostat or regulator with transmitter mounted in direct connection to the element.

The heating foil is also available in a special design as can heaters and are supplied with earth‐leakage‐circuit‐breaker mounted on rubber tube for connection.

• Easy and quick installation.

• Resistant against most of the chemicals.

• Flexible at temperatures down to ‐28°C. Make it easier at installations in the winter.

• Are available in a large number of standard elements.

• Operating temperatures up to +250°C.

• The construction is easy to apply in the most applications where the object is constructed of a heat discharging material, this admits its also an excellent heat transfer from the element to the object, which gives a long lifetime and a low energy consumption.

Nozzle heaters for mounting on round object, as for example pipes where extremely high outputs (4‐6W/cm²) is required, available in standard sizes. Max continuous operating temperature 450°C.

Immersion heaters for high outputs (30‐40W/cm²). Operating temperature max.1000°C Continuous.


Chapter 3 Calculations Frost protection and heating of pipes

Formulas for pipe heating

1. Frost protecting/heating of pipes. Pipes are covered with heating cable in order to compensate the heat losses through the thermal insulation and maintain a temperature over 0°C, maintain the required temperature.

Formulas

Heat loss calculation

Q = 2 x Π x Δt x k x 1,16 x s ln (dy / di)

Q = The heat loss (W)

Δt = Difference in temperature between the pipe and environment (°C)

K = The permeability of the insulation material in W/m°C (Mineral wool =0,045)

dy = The exterior diameter (mm)

di = The interior diameter (mm)

s = Safety factor (0=indoor/1,5=quay berth)

2. Heating of pipes (unprogressive fluids). Pipes

are covered with heating cable to rise the original temperature to a required temperature and to compensate heat losses through the thermal insulation.

Calculation of required energy at heating of unprogressive fluids

P = Q + ph

Ph = G x V x c x th

h

P = Total required power for the required temperature rise (W)

Q = Heat loss through the thermal insulation according to above (W)

Ph = Required power to increase the temperature(W) G = Density (Kg/dm³) V = Volume dm³ (l) c = Heat permittivety (Wh/Kg°C) th = Required temperature rise (°C) h = Required heating time

3. Heating of flowing fluids. Pipes are covered with heating cable to rise the temperature on a flowing fluid a number of degrees, while it passes the actual pipe length. At the same time the heat loss through the thermal insulation be compensated.

Calculation of energy requirement for heating of flowing fluids

P = Q + Phs

Phs= V x G x c x th

P = Total required power (W) Phs= Required power for required temperature rise (W) Vh = Flowing volume (Litre/hour)

c = Heat permettivety (Wh/Kg°C) th = Required temperature rise (°C)


13


Need of compensation for heat loss

A pipe system does no only consist of the pipe itself, it also includes pipe supports, ventilators, flanges, pumps and instrument. All these components contribute to heat losses and they have often a larger surface than the pipe itself. The heat loss is therefore bigger on these places than for the pipe in general.

For ventilators, pipe supports, pumps can the factors below be used to calculate increased heat losses on these. A pump has approximately the double heat loss than the ventilator as for example.

Supplementary factors for ventilators and mounting details

Key ventilator 1.3 x Q/m pipe Moving butterfly valve 0.7 x Q/m pipe Bullet valve 0.8 x Q/m pipe Mushroom valve 1.2 x Q/m pipe Flange 4 x Dflange x Dpipe Pipe support 2 x width of the pipe support + 0.4m

Heat losses from a pump can also be calculated approximately as a barrel. The diameter of this barrel is the same as the distance between outlet flange and the base plate. The length is the same as the distance between the inlet flange and the opposite end of the pump. The heat loss from the shell of the pump can be determined by using this formula:

Q pump =k π D (0,5 x D+L)x Δt (W) d

Instrument included along the pipe is most often covered by the heating cable which runs on the piping are laid around the instrument. You must specially consider the electronically equipment which are used. The does in general not handle temperatures above 80 ‐ 100°C due to incoming electronically component, solderings etc.

Projecting a heating cable application

Projecting can be divided into two directions which has their own:

a. Heating – heat loss compensation/frost protection

b. Heating up

Which information must be available as a minimum to be able to project?

HEATING UP

‐ Type of insulation and thickness

‐ Lowest ambient temperature

‐ Required temperature

‐ Pipe dimension

‐ Type of insulation and thickness (k‐value)

‐ Maximum process temperature

HEATING UP – Supplement to keeping warm

‐ Pipe material and its thickness

‐ The content of the pipe: Density, heat permittivity

‐ Inlet temperature of the pipe/its content

‐ Final temperature after heating

Required heating‐up time

*At percolation even fluid volume

In both cases this is the absolute minimum demand which is required for a projection. To do a complete projection you also must take in consideration a couple of factors according to below.

FURTHER INFORMATION

‐ If the application is located within an Ex‐rated area or not.

‐ Maximum operating temperature

‐ Eventual steam bubbling (choose of cable)

‐ Available supply voltage

‐ Which direction of the fluid (placement of transmitter)

‐ Type of control equipment (existing/required)

‐ If there is need of a limiting thermostat (temperature sensitive fluids, substances)

‐ Valves, pumps, instruments

‐ Required special cable type

‐ If the application is located indoors or outdoors

‐ High gradients on pipes (chimney effect)

‐ Type of insulation (k‐value)

‐ Suitable material to fix the heating cable

‐ Surrounding environment (acids etc.)



Example on calculations Calculating heat loss for pipes

Calculating heat loss for pipes: To do a calculation of heat losses on an insulated pipe your have to know certain data: required operating temperature, pipe dimension, the thickness of the insulation and conductivity, the nature of the environment.

Dt = Difference of temperature (the difference between the operating temperature and the lowest ambient temperature)

k = The heat permeability of the insulation (W/moC) (Mineral wool 0.04)

dy = The exterior diameter ( mm )

di = The exterior diameter of the pipe (mm)

S = Safety factor 1,2 ‐1.5 (1,2 indoor ‐ 1,5 outdoor)

Q = 2 x � x Dt x k x 1,16 x S ln (dy / di)

Q = Heat loss per meter pipe (W/m)

The required power (Q) can also be read from the table xx.

NOTE!

If the pipe is made of plastic and the required power (Q) exceeds 10 W/m can heating cable of parallel resistive or series resistive type only be used at frost protection and if double insulation is done, i.e. you insulate the pipe with a thin insulation and then lay an aluminium foil which the heating cable is applied and cover with a extra layer of aluminium foil as the final insulation layer is laid.

Example

Operating temperature: +40 °C

Ambient temperature: +10°C indoor

Pipe dimension: Ø 30 mm steel

Insulation: Pipe tray 30 mm glass wool

Insulation k‐value: 0,036

Safety factor: 1,2

Q = 2 x π x Dt x k 1,16 x s ln (dy / di)

Q =2 x π x 0 x 0,036 1,16 x1,2 ln (90 / 30)

Q = 8,6 W / m

Choice of cable, see page 21


15


Choosing cable

Now when we have calculated the heat loss from the pipe, we need to decide which cable we shall use.

For this one have to know the information below:.

Construction data:

Max. operating temperature (ev. steam purifying)

Tp = ° C

Required maintenance temperature

Tm = ° C

Chemical environment ‐ required sheath type __________

T‐rate/Ex‐zone ___________________________________

Pipe material (Metal/Plastic) ________________________

1. Considering temperatures

Decide the cable type, which is suitable for the operating temperature of the application and maintenance temperature in the design with help of our data sheets. Control that the stated values for temperatures, switched on and off not is exceeded.

2. Choose the material for the sheath

To decide the outer sheath of the cable you should take into the consideration to the environment where the cable shall be installed. Process temperature, steam purifying, aggressive fluids, ex‐zones, moisture etc, see diagram on page 11.

3. Choosing cable

Self‐limiting cable type is decided from our data sheets, in the diagram can the output be read which the different cables emit at your required operating temperature. The cable is very well suited for coiling to obtain required output.

Parallel resistive cable is chosen so that the output per meter corresponds to the calculated required power (Q) or higher. You can also obtain the required power by coiling (without crossing the cable). Control the diagram in the data sheets for the heating cable that the sheath temperature (Tm) not is exceeded.

Series resistive cables Mineral insulated Teflon and PVC‐cables are chosen from our data sheets. Calculation of the ohm‐value for the required cable length and output (see page 23). To determine the cable type is the power loading related per meter with the process temperature. (See page 31.)

Table 2.Choosing cable type

Type of cable Cable on Cable off

Self‐limiting SRL 65°C 85°C SRM 120°C 190°C

Parallel resistive CWM 120°C 200°C

Series resistive Teflon insulated TCT/TCTR Depending on load 200°

Mineral insulated COPPER Depending on load 250°C

COPPER/NICKEL Depending on load 450°C

STAINLESS* Depending in load 600°C

*In environments saturated with salt can stainless cables corrode with short‐circuiting as a result.

Example:

Environment = Exposed to moisture Voltage = 230 V Pipe material = Metal

Tp = 65oC,

Tdrift = 40oC

Required power = 10W/m

1. 1.Both temperatures are below the maximum temperature data for all cable types (all cable types can be used).

2. SRL ‐5‐ gives 10 W/m at 40oC.

3. 3.EST/CWM 12‐4 gives 10 W/m cable at 230V

4. Series resistive cables, see page 23.

If required running meter output not can be obtained

Possible steps:

• Coil or lay several runs with cables.

• Increase the thickness of the insulation or choose insulation with better k‐value.

• Choose any of our miscellaneous heating products (for example silicone element or nozzle heaters).



Calculating the amount of cable

CabLe Length

Pipe length (Lpipe) = ______________________ m

Type of valve = _______________________

Number of valves = _____________________ pc

Flanges = _____________________ pc

Number of pipe supports = _____________________ pc

The total length of cable needed is obtained by add the pipe length and the components.

L = Lpipe x coiling + Lsupplement

Lr = The pipe length A is known from above

Lsuppl. = (Qpipe x number of valves x factor for the type/Qcable)

+ (Number of pipe supports x 2 x pipe diameter(m) + (Number of flanges x 2 x pipe diameter(m)

The factor for the heatloss in valves, see table on page 19.

Be sure that the cable length not exceeds the maximum recommended length, which is shown in table 3 below.

Table 3. Max connection lengths

Cable symbol Max. connection length

(m) at 240V

Self‐limiting SRL3 211 SRL5 166 SRL8 127 SRL10 109 SRM3 237 SRM5 228 SRM8 185 SRM10 149 SRM15 128 SRM20 106

Parallel resistive CWM12‐4 (10/30 W/m) 300/180 CWM8‐2 (24 W/m) 160 CWM12‐2 (36 W/m) 120

Series resistive teflon‐ and mineral insulated cables, see data sheets.

Calculate maximum circuit lengths

Fusing – self‐limiting cable

Calculate the starting current with help of the formula below to determine supply cable and fusing.

Formula:

I (A) = L x Istart

L(m) = Length of cable

Istart(A) = Starting current/m see table below

Table Start current Self‐limiting cable

Start current (A/m) – Start temperature (°C)

Type of cable Operating temperature

‐20°C 0°C +10°C +20°C

SRL3 0,162 0,137 0,125 0,112 SRL5 0,333 0,25 0,206 0,162 SRL8 0,526 0,4 0,323 0,27 SRL10 0,625 0,54 0,488 0,465

SRM3 0,161 0,137 0,125 0,112 SRM5 0,25 0,217 0,206 0,192 SRM8 0,339 0,297 0,287 0,272 SRM10 0,37 0,345 0,333 0,313 SRM15 0,41 0,382 0,369 0,355 SRM20 0,5 0,457 0,432 0,41

Example

Length A = 100 Type of valve =1 pcs claw valve Flanges = 8 Pipe supports = 8 We calculates the total length of cable

LTot = 100 +14 = 114 meter

Lsupport = (8,6 x 1,3/10) + (8 x 3 x 0,3) + (8x2x0,3) m= 13,11 m

We obtain a total length of 114 meter of the chosen cable SRL‐5 2CR. The cable thermostat switch on the current at +40°C The cable can be connected in one end but is then require a 25A time fuse due to the starting current of the cable (see table above). You can instead divide the cable in two parts in the same size and carry out the connection on the middle to 2 x 16A. This also gives a more even load of the fuses.


17


Choose the cable type

Series resistive heating cables are a good alternative for longer pipe systems except for Ex‐rated zones.

For frost protection can for example TCP/TCPR be used if the environment allows pvc‐sheaths.

For heating‐up to 180°C, use TCT/TCTR which is teflon sheathed and therefore works excellent in the most aggressive environments.

Mineral insulated heating cables are a good alternative for long pipings or when high outputs or temperatures up to 500°C shall be maintained or are obtained in a pipe system.

Take out the values according to the points below:

* Heat loss in Watt per meter, Q (W/m)

Use values calculated according to the formula on page 18.

* Length of cable, L (m) The length is made double at single wire.

Use lengths calculated according to page 22.

* Supply voltage U

Find out which supply voltages are available.

* Calculate requisite cable resistance per meter

R/m = U2 /(LxQ) / L

* Choose the correct resistance value

Choose a cable, which have the calculated resistance value or the cable closest below the calculated value from the table for required type of cable.

* Sheath temperature

Always check that your calculated heating loop not exceeds the maximum sheath temperature for the cable type in question, see diagram on the data sheets.

* Calculate the current consumption of the loop

I (A) = Qtot / U (V)

* Choose cold‐lead‐in cable area and length.

Cold‐lead‐in cable is chosen in the same way as the installation cable with consideration to fusing.

* Divergent resistance as a result of high temperatures

In heating cables with high copper‐bear in the heating conductor, the resistance is influenced proportionally to the temperature.

For these cables a α–value often is stated which can be put in the formula below.

Recalculate the cable resistance with help of the formula at the required maintenance temperature

R/m = R20°C @ (1+(T‐20))

Calculate the output, which the cable obtains at operating temperature and see if this fall below your required power. If so, choose the closest lower resistance and check calculate this.

Exempel:

Q = 8,60 W/m.

L = 114m.

U = 230 Volt.

P/m = 8,6 W/m

Ptot = 114 x 8,6 = 980W

Tmax = 500C

R/m = 2302 / 980 / 114 = 0,473W/m

CHOICE OF CABLE:

Bearing the low output in mind and the relatively low operating temperature can all type of cables be used, for example series resistive PVC and teflon‐cables or SRL self‐limiting.

Wee choose TCTR 0,42 from the data sheets under the red patch on page HD:100

Check calculation:

P = 2302 / 114 / 0,42 = 1105W

P/m = 1105 / 114 = 9,7 W/m



Choosing type of cable

Projecting with parallel resistive heating cable

To be able to determine the consumption of material in an application with parallel resistive heating cable you should take out following data:

• Number of meter pipe

• Required power for the different pipes (see page 18)

The coiling rate is stated according to below: S Q / P S = Coiling factor Q = The required power of the pipe P = (The output/m of the cable)

• Decide which cable power giving the best economy. If a piping has several different dimensions, this can be compensated of increased insulation thickness, multiple cable runs or *coiling of the cable.

• Other valves, flanges, pumps etc.

Parallel resistive heating cable is used at piping systems where you require relatively low connection lengths, but not in advance can determine the exact sizes of the pipe length. At installations where the pipe has a T‐branching these are carried out with a box on the exterior side of the insulation where the heating cables are connected in parallel.

VÄRMEKABELTEKNIK:s EST/CWM‐cables has a layer of insulation and sheath of teflon and is available with three outputs

Type of cable CWM

Power (W/m)

Voltage (V)

Max. length(m)

12‐4 CT 10/30 230/400 300/180

8‐2 CT 26 230 160

12‐2 CT 36 230 120 The above max. connection lengths are established on max. 10% voltage drop in the conductors. This to maintain a max. 20% power drop in the final end of the cable. (Max. connection length includes the length, which can be connected from one place of connection).

The EST/CWM‐cables can easily be spiralised or be installed in several cable runs to obtain required power.

Maximum process temperature, see data sheet EST/CWM

The cables are bought in running metre and is easily completed with our connection/end termination kits on the site with help of some tongs and a hot air pistol or bottled gas burner.

Example:

Q = 14 W/m.

L = 114m.

U = 230 Volt.

P/m = 14 W/m

Ptot = 114 x 14 = 1596W

Tmax = 500C

Environment = Leakage of acid can occur

Cable choice:

Bearing the low output in mind and the relatively low operating temperature can all type of cables be used, for example series resistive PVC and teflon‐cables or SRL self‐limiting.

We choose CWM 12 from the table in the left‐hand column. The cable is designed in teflon, which makes it resistant in most chemical environments.

Since the heating cable emit 12W/m we must spiralise according to the formula:

S = Q / (P/m) = 14 / 12= 1,17 m cable / meter pipe

Our cable need is then 1,17 x 114m = 134 meter + 1 meter to connection‐ & end termination end.


19

Chapter 4 Calculations Frost protection, heating of cisterns, containers, bunkers & screens

Calculating the energy requirement

MAIN GROUPS

1. Frost protection/heating of tanks, containers, screens, bunkers, cisterns etc. The object is covered with heating cable, aluminium foil and thermal insulation to prevent freezing (heat losses through thermal insulation).

Formulas

Heat loss calculation

Q = A x k x �t x s

S x E

Q = Heat loss through the thermal insulation (W)

A = The total frozen area of the object area (m²)

k = The permeability of the insulation material

Δt = The difference in temperature between the object and environment

S = The thickness of the insulation (m)

E = Correcting factor normally 0,8

s = Safety factor (0=indoor/1,5=quay berth)

2. Heating of tanks, containers, screens, cisterns etc.

The object is covered with heating cable, aluminium foil and thermal insulation, partly to compensate the heat loss through the insulation and to rise the temperature at the object.

The heating‐up time depends on installed power according to formula.

When calculating considerations should be taken to heat losses through the thermal insulation since this can prolong the calculated heating‐up time some.

Calculating the energy requirement for heating

P = Q + Ph

Ph = V x G x c x th

h

P = Required power (W)

Q = Heatloss through the insulation (W)

Ph = Required power to increase the temperature on the object to required temperature in hours (W)

V = The volume of the object dm³ (Litre)

G = The density of the content (Kg/dm³)

c = Heat permittivity (Wh/Kg°C)

th = Required temperature increase (°C)

h = Heating‐up time



Heat on cisterns, containers, screens and bunkers

Calculate the heat loss for containers

To calculate heat losses on an insulated container, you have to know certain data. Required operating temperature, ambient temperature, the thickness of the insulation and conductivity, the total cooling area of the outer sheath and the nature of the environment.

A = The total cooling sheath surface (m²)

Dt = Difference in temperature (the difference between the operating temperature and the lowest ambient temperature)

k = The permeability of the insulation material

(W/m°C) (Mineral wool 0.04)

S = The thickness of the insulation ( m )

s = Safety factor 1,2 ‐1.5 (1,2 indoor ‐ 1,5 outdoor)

A x Dt x k x s Q = S x E

Q = Total heat loss (W) NOTE! If the object is made of plastic material or if the content is temperature sensitive it is always recommended using self‐limiting cable. If a cable of parallel resistive or a series resistive type is chosen, shall the sheath temperature be calculated so that it does not exceed the temperature for the –material or the medium in the container.

Example

Frost protection of a round, standing tank

Diam. = Ø 1500 mm

Height = 3 meter

Dt = 40°C

S(m) = The thickness of the insulation 50 mm mineral wool

k‐Value = 0,04

Environment = The tank is placed within flammable surface

Q = A x k x Dt x s (W)

S x E

Q = 6,5 x 0,04 x 40 x 1,2 = 313W

0,05 x 0,8

The required power to keep the tank on plus degrees at ‐ 35°C will be 313W. The cable is chosen so that the c/c distance does not exceed 30cm to prevent freezing against the tank wall between cable runs.

Since the application is located within a flammable surface, we choose a self‐limiting cable, SRL. This cable is EX‐rated and T‐rated which means that it can be used within the most flammable and explosive environments.

To obtain the most economical choice of cable and at the same time handle both the required power and the maximum c/c‐distance we choose a 22 meter SRL‐5 which gives 17W/m at +5°C which gives a total output of 375W / 230V.


21


Calculation of requisite power to heat containers and its content.

* At heating of containers, must also the heat loss through the thermal insulation be taken into consideration.

* The calculation for this is carried out according the previous page and be added to the calculated required power for heating.

* The calculation of the required power to increase the temperature in a container to a required temperature on an appointed time, data is required according to following:

Final temperature after heating, start temperature, thickness and conductivity, the thickness of the insulation and conductivity, the total cooling surface of the outer sheath and the nature of the environment. Also information about the volume of the container, the density of the content and heating permittivity and required heating‐up time is required.

Ph = V x G x c x th + Q

h

Q = Heat loss through the insulation (W)

Ph = The required power to increase the temperature th degrees on h hours.

V = The volume of the container (dm3 )

G = The density of the content (Kg/dm3)

c = The heating permittivity of the content (Wh/Kg°C)

th = Required temperature rise (°C )

h = Heating‐up time (Hours)

NOTE! If the object is made of plastic material or if the content is temperature sensitive it is always recommended using self‐limiting cable. If a cable of parallel resistive or a series resistive type is chosen, shall the sheath temperature be calculated so that it does not exceed the temperature for the –material or the medium in the container.

EXAMPLE Heating a round, standing tank of steel Containing oil

Diameter = Ø 1500 mm

Height = 3 meter

Ambient & start temp. = 20°C

Required temp. = 80°C

Insulation D(m) = Mineral wool 0,05m

k‐Value = 0,04

Environment = The tank is located indoors, oil retains can occur.

The density of

The content (G) = 0,9 (Kg/dm3)

Heat permittivity (c) = 0,58(Wh/Kg°C)

Heating‐up timeh = 24 hours

Ph = The required power to increase the temperature on the object to required temperature on h hours (W)

Volume V(l)= π x r² x h =π x 7,5² x 30=5298 dm3

Ph = V x G x c x th = 5298 x 0,9 x 0,58 x 60 =

h 24

Ph= 6913 W

P = Total required power (W)

P = Q + Ph = 468 + 6913 = 7381 W

The tank is made of steel and the oil withstands high temperatures so we choose a series resistive cable of teflon with high power per meter. Connection is done by temperature control.

We choose the TCTR‐cable with 28W/lm. This gives:

3 pcs heating cable loops á 86 meter TCTR 0,25 ohm 2460W / 230V



Screens and bunkers, si l icone rubber element

Elements of silicone rubber gives may advantages:

* Easy and quick installation.

* Resistant against the most frequent chemicals.

* Flexible at temperatures down to ‐28°C. Makes it easier to install during the cold period.

* Available in a large number of standard elements.

* Operating temperatures up to +250°C.

* The construction is easy to install in the most applications where the object is made of a heat conducting material, this admits also an excellent heat transfer from the element to the object.

At high power requirements or when the object has few free plain surfaces to cover with heat (a filter can be full of openings and a tank can be armoured), then elements of silicone rubber is a good alternative. They handle temperatures up to 250°C and have an output of 1W/ cm²

To obtain a good heat transfer from the panel to the cistern (air is as is well known, a very good insulation), the panel is glued with silicone glue, type 732 RTV. A tube 732 RTV is enough to 2 panel’s 600 x 600 mm. This can be done in the following way:

1. Remove the grease from the element and the surface where the element shall be installed with trikloretylen or equivalent.

2. Distribute the glue evenly over the whole surface of the element, with a toothed glue spreader (minimum layer of glue approx. 0.5mm).

3. Correct placement of the element is important in order to obtain the best functioning and best life time (if it is a cistern containing fluids in varying levels, shall the element be mounted so it will be under the fluid level. Is this not possible you can divide the application in two parts on the height with separate control.

4. Mount the element against the cleaned surface and press out all air bubbles with a rubber roller or another round thing which is reeled on the outside of the element from the middle and outwards the edges. You can fix the elements with aluminium tape to keep them on place until the glue gets dry. NOTE! The glue will dry in the edges first and at last in the middle.

Applications with silicone rubber element should normally be equipped with a quick control, for example a time proportional regulator with the transmitter placed against the heated surface or on the silicone element.

Heating of a round, standing tank of steel containing oil

*Diameter = Ø 1500 mm

*Height = 3 meter

*Ambient‐& start.temp. = 20°C

*Required Temp = 80°C

*Insulation D = 0,05 m Mineral wool

*k‐Value = 0,04

Environment = The tank is placed indoors. Oil detarding can occur.

The density of the

Content G = 0,9 (Kg/dm3)

Heat permittivity c = 0,58(Wh/ Kg°C)

Heating‐up time h = 24 hours

Volume V= π x r² x h =π x 7,5² x 30=5298 dm3

Ph = V x G x c x th = 5298 x 0,9 x 0,58 x 60

h 24

Ph= 6913 W

Ph = The required power to increase the

temperature to a required temperature on h hours (W)

P = Total required power (W)

P = Q + Ph = 468 + 6913 = 7381 W

The tank is made of steel and the oil withstands high temperatures so we choose silicone rubber element, which is glued against the outer side of the tank with silicon glue. Connection is done via temperature control.

We choose 6 elements 200 x 900 mm 1285W 230V which gives a total power of 7700W /230V


23

Chapter 4 Calculations The sheath temperature of the heating cable

Determining sheath temperatures in applications against the pipes

If the cable is free in air, the heat transfer will be poor, but if the cable is fixed with aluminium tape the heat transfer will increase considerably.

This gives us the following formula:

Q Ts = uA + Tp

Q = W/m The output of the heating cable per meter

A = m²/m The surface of the heating cable/m cable.

u = W/m²°C Heat transfer coefficient

u = Loose cable against pipe 17 ‐ 28W/m²°C

u = With aluminium tape 57W/m²°C

Ts = °C Sheath temperature

Tp = °C Process temperature

A is determined in accordance to following:

A (m²) = π x D (m)

D = The diameter of the heating cable (m)

The determination of parallel resistive and series resistive heating cables sheath temperature is easy, since the output is constant which it isn’t for self‐limiting heating cables.

To be able to determine the sheath temperature for a self‐limiting heating cable you should go to the data sheet and in the output diagram read the emitted output at the required process temperature, i.e. the temperature that the thermostat/regulator of the heating cable is set on.

Example

Series resistive cables TCT

20 Ts = 0,009 x 57 + 50°C = 87°C

Heating cable 20W/m mounted with aluminium tape, process temperature 50°C

Series resistive cables TCTR

20 Ts = 0,016 x 57 + 50°C = 72°C

Heating cable 20W/m mounted with aluminium tape, process temperature 50°C.

Parallel resistive cable EST/CWM

20 Ts = 0,024 x 57 + 50°C = 65°C

Heating cable 20W/m mounted with aluminium tape, process temperature 50°C.

Self‐limiting cable SRL

15 (SRL‐10) Ts = 0,032 x 57 + 50°C = 59°C

The heating cable gives approx. 15W/m at process temperature 50°C mounted with aluminium tape.

Self‐limiting cable SRM

20 (SRM‐8) Ts = 0,032 x 57 + 50°C = 61°C

The heating cable gives approx. 20W/m at process temperature 50°C mounted with aluminium tape..


Chapter 5 Installations within explosive areas

Area classif ication

Within chemical, petroleum and technical industry there is ex‐rated and flammable environments. Depending on the substances which are considered to make up the risks and the extent of their occurrence, these areas has been divided into zones.

Zone 0 ‐ Constant presence of explosive substances.

Zone 1 ‐ Temporary presence of explosive substances at normal operation.

Zone 2 ‐ Occasional presence of explosive substances (not present during normal operation).

For the zone grouping there is determined norms. The authority that can be asked at uncertainty regarding work and zone groups and material allowed to be used is ”Sprängämnesinspektionen” (Inspection for explosives). To make installation work easier, there is on the most industries a rating map. This map informs about the different zones present within the industrial surface. In the case a map is not available a judgement of the area must be carried out.

Explanation of zone division

Zone 0 There it always is a risk of explosion. This is found inside tanks, cisterns and in pump rooms and such spaces where fluids, easily set on fire and gases are expected to be present continuously.

Zone 1 Here an explosive risk at for example reloading, fillings, valves and at taps of fluids, easily set on fire and gases, valves etc.

Zone 2 areas except zone 1 within an Ex‐area.

As a complement to the zone division, is temperature‐ and gas group classification. According to the Cenelec norm (Cenelec stands for Comite Europeen de Normalisation Electrotechnique) it is decided upon following temperature classes.

Class Max.temp. Gas group identification T1 above 450°C T2 300°C T3 200°C T4 135°C IIA T5 100°C IIB T6 85°C IIC

The temperatures which are stated in the table is the maximum temperatures which may be present on the material, for example heating cable which may be used at an ambient temperature of 40°C.

Special attention is directed against group II C (hydrogen). 2 H2O2 2 H2O + O2.

If two gas groups are mentioned in same specification, for example II B and II A, the whole surface is rated as II B.

All equipment, which shall be installed in an Ex‐rated surface, must meet the sealing class, which are prescribed for the zone.

Below is a list over the symbols that are used.

Exe ‐ Increased safety

Exd ‐ Inflammable

Exp ‐ Pressure adapted

Exs ‐ Special protection

Exm ‐ Casted design

Exo ‐ Filled with oil

Exi ‐ Interior safety

Exq ‐ Filled with sand

Description of the norms is available in Europanormer EN‐50014‐50020.


25


EX-approved material

Products can be approved in accordance with local regulations or European norms. The European norm is market with an extra E in front of the Ex‐symbol.

Example

Exd II B T6

Flame proof to local norms Gas group Temp.class

Eexd II B T6

Flame proof to European‐ Gas group Temp.classnorms

There are still countries which norms not is harmonic/corresponding. The testing authority of the different countries has different interpretations of the norms. Heating cables are still an open question in many countries. This implies that for example in Belgium or in England can be possible to use a cable, which is not accepted, in Germany or in Sweden and in contrary.

Testing authorities available are:

Netherlands Germany Sweden

INIEX P.T.B SEMKO

Norway Denmark Finland

NEMKO DEMKO FIMKO

Except from the flame‐proof tests there is also electrical and mechanical tests on for example the thickness of the insulation in the temperature class, heat‐ and cold resistance in the screen, heat from the cable, sheathing, tensile strength, flexibility, bending strength, temperature strength etc. These tests can be carried out by:

Netherlands Germany Sweden

INIEX V.D.E SEMKO

E.P.M. SP ‐ Statens Provningsanstalt i Borås

Norway Denmark

NVD DEMKO

DNV

Ex-approved junction boxes with a pipe support, which are integrated in the insulation and in the same time protects the heating cable.

Ex-approved heating cables SRL and SRM.

Ex-approved connection- and end termination kits for heating cables where fitting is included



Sealing classes SS EN 60529

First number: Protection against contact and penetrating objects

Second number: Protection against fluids

0 1 2 3 4 5 6 7 8

0 IP00 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

1 IP10 IP11 IP12 ‐ ‐ ‐ ‐ ‐ ‐

2 IP20 IP21 IP22 IP23 ‐ ‐ ‐ ‐ ‐

3 IP30 IP31 IP32 IP33 IP34 ‐ ‐ ‐ ‐

4 IP40 IP41 IP42 IP43 IP44 ‐ ‐ ‐ ‐

5 IP50 ‐ ‐ ‐ IP54 IP55 ‐ ‐ ‐

6 IP60 ‐ ‐ ‐ ‐ IP65 IP66 IP67 IP68

First number: degree of protection against contact and penetrating of fixed objects

Second number: Degree of protection against penetrating fluids

0 No protection against penetrating objects. 0 No protection.

1 Protection against contact of dangerous parts with the backside of the hand or object with a diameter larger than 50mm.

1 Protection against vertical falling water drops.

2 Protection against contact of dangerous parts with a finger or fixed objects with a diameter larger than 12mm

2 Protection against vertical falling water drops when the sealing inclines max. 15°C.

3 Protection against contact of dangerous parts with tools or fixed objects with a diameter larger than 2.5mm

3 Protection against sprinkling water.

4 Protection against contact of dangerous parts with wire or fixed objects with a diameter larger than 1mm.

4 Protection against sprinkling.

5 Protection against contact of dangerous parts with wire. Dust guard.

5 Protection against water jets.

6 Protection against contact of dangerous parts with wire. Dust guard.

6 Protection against heavy water jets.

7 Protection against influence at short immersion in water.

8 Protection against influence at long immersion in water.

When you choose material to an application you shall make sure that the IP-rate of the chosen material at least corresponds to the zone class available for the area or as in description stated class for the application.


27

Chapter 6 Electrical installation

Electrical design

a) Parallel resistive cables CWM/EST

Voltage 230 ‐ 400 V

Output 10 ‐ 36 W/m

At a normal electrical installation within the industry the fuses most often is maximised to 16Amp. The fuses should have C‐characteristic. This means that you per circuit can load maximum 3680W/230V and 6400W/400V 2‐phase. It is though realistic to use 80% of the fuse capacity, when the fuse at group mounting on a bar emit self heat which influences the release circuit and partly to be able to do smaller supplements in the application without changing the sizes of the fuses and supply cables.

Max. capacity at 230V will be 3680 x 0,8 = 2945 W. I.e. when EST‐10 has been used with a maximum length:

2495 5120 L1 = 10 = 294m L2 = 10 = 512m

Voltage drop in the conductors:

UL = RI / UL = L x W copper x number of conductors x current

At 230V

294 x 0,017 x 2 UL1 = 2,5 x 12.8A = 51 V

Vid 400V

512 x 0,017 x 2 UL2 = 2,5 x 12.8A = 89 V

it means an decrease of the output in the end of the circuit on approx.:

(1‐U²end) U% = U²feed x 100

At 230V At 400V

(1‐179²) x100=39% (1‐311²) x 100 = 39% 230² 400²

It is too much, in case that we allow a 10% voltage drop, it should mean a voltage loss of 19%.

10% voltage drop = 23 V/40V.

If you allow a higher voltage drop this can bring a too low output in the end of the cable.

b) Self‐limiting cables (SRL, SRM)

When using self‐limiting heating cables the connection lengths are limited as a function of their start currents and the fuse of the circuit.

The start current is instantaneously operating and the max. lengths stated as a result of the starting currents are therefor not be the cause of any considerable power loss in the end of the cable.

NOTE! Use fuses which manages the requirements of the industry

VÄRMEKABELTEKNIK use fuses from Siemens in their control cabinets.

Type of cable Nominal Start‐ A*start‐ output current/ current‐ (+10°C) meter factor SRM3‐2CT (10W/m) 0.091 A/m 1,6 SRM5‐2CT (16W/m) 0.153 A/m 1,8 SRM8‐2CT (26W/m) 0.195 A/m 1,5 SRM10‐2CT (33W/m) 0.296 A/m 1.8 SRM15‐2CT (49W/m) 0.421 A/m 1,8 SRM20‐2CT (65W/m) 0.5 A/m 1.5

The starting current is based on the temperature - 20°C at 230V. Type of cable Nominal Start‐ A*start‐ output current/ current (+10°C) meter factor SRL3‐2 (10W/m) 0.12 A/m 2,8 SRL5‐2 (16W/m) 0.266 A/m 3,8 SRL8‐2 (26W/m) 0.421 A/m 3,8 SRL10‐2 (33W/m) 0.5 A/m 3,5

The starting current is based on the temperature ‐ 20°C at 230V.



Available supply voltage

The available supply voltage have some importance when also parallel resistive cables in spite of that they is specified to a certain output and the supply voltage can be connected to varying supply voltages to obtain varying outputs.

Parallel resistive cables can be used from 100V up to 400V by following calculation:

U² disposable U²cable x Pcable = Pemitted (W)

You have to consider not exceeding the highest stated rated voltage for the cable and the maximum output, which the cable withstands considering the max. operating temperatures.

See further on the cable data sheets.

e.g. CWM/EST 10/36 gives 10 W/m on 230V

gives 36 W/m on 400V

CWM/EST 24 gives 24 W/m on 230V

CWM/EST 36 gives 36 W/m on 230V

Self‐limiting heating cables (SRL, SRM) can only be connected to 230V (+‐20V) (can be specially ordered for 110V). The material in the cable core is adapted to the stated voltage. You can not, regarding self‐limiting heating cables, use a 230V cable on a 400V installation.

For series resistive cables the conditions are the reversed since the output is a function of:

a) The resistance of the cable (Ohm/m)

b) The length

c) The connection voltage

Regarding series resistive cables can the required lengths and connection voltages be varied free to obtain required lengths with adapted outputs. Though, you have to consider the test voltage of the cable and the recommendations from the supplier regarding output per meter at varying temperatures and way of installation.

Note. Lengths of series resistive type are finished on the site, which limits the flexibility for this product in contrary to the both earlier mentioned cable types.

Electrical installation EX-rated areas

It is quit normal than you within a classified area must choose material that meets requirements available. It means that all cables, connection boxes, fittings, end terminations, must be approved for this range of application.

To be more specific:

The cable must be Ex‐approved and meet the temperature class required for the surface. The connection in the junction box must be Ex‐approved and have required IP‐class. Even components that are used inside the boxes shall be Ex‐approved. Clips, clamps and fittings must be approved and have the same class as the boxes. In short, the whole application is rated after the weakest link. It is not of any help to use a classified junction box if you use a standard fitting.

In the most countries in Europe it is not permitted to do T‐joints under the insulation. It should be done in a box outside the insulation so that it is easy to reach. In some installations the thermostat is placed outside the application. Thermostat and enclosure should in these case be Ex‐approved.

Thermostats and other automatic equipment can very well be placed outside the Ex‐zone, if the thermostat don’t have Ex‐approval, this requirement can be provided with a Zener‐barrier on the conductor.

Velox cable protection is used to obtain a protected connection of heating cable on insulated pipes.


29


Fusing of heating cable

Circuit breakers of standard type have a breaking curve, which allows an instantaneously operating current, three to five time its nominal value. The breaking curve admits only one very short current pulse.

This mean if consideration is not taken to the starting current of a self‐limiting cable, the fuse will unconditionally switch off in the moment of switching on.

As soon as the current in for example a self‐limiting cable pass the limit for the field where magnetic release of the fuse is done the current is switch off instantly.

This can be solved in two ways:

1) Over dimensioned fuses (five times larger than the operating current). This causes a negative effect since the areas of the supply cables must be increased with much more than the ones required for the operating current.

2) Limitation of the lengths together with switch delay between the cable groups gives an economical design of the heating cable application.

Limitation of cable lengths as a result of the cable construction

Max. lengths as a result of voltage drop in the electric conductor of the heating cable extend both self‐limiting and parallel resistive cables. If you exceed the stated max. length in the data sheet, will the voltage drop give a lower output in the end of the cable.

When using self‐limiting heating cable should the voltage drop in the electrical conductors be calculated at the output at operating temperature. As a rule, the voltage drop in the conductor is not determining the length for a self‐limiting heating cable when starting currents related to fusing and supply cables limits the cable lengths to relatively moderate number of meter.

This does not influence heating cables of series resistive type when the same current traverses the whole loop irrespective of length. It should be mentioned that with series resistive lengths with build‐in return‐wire, considerations should be taken to the resistance of the return wire at lengths over approx. 200m and high outputs.

When using series resistive at high temperatures (normally mineral insulated heating cables, MI‐cable) where some types have high copper content in the heating conductor, have an increasing resistance as a result when the conductivity of the copper is decreased with rising temperature. Formula and temperature coefficient is available in the data sheets for these cables.


Chapter 7 Control and Alarm

Thermostats, l imiters, supervising, alarm

The market of today offers a large number of thermostat‐, regulator types and computer based control systems.

This gives possibilities to exquisite functions for high and low alarms, temperature readings, logging of temperatures and ratings and control with miscellaneous control curves and soft starts with learning functions which neutralises overshoot at start‐up. Different applications require different accuracy and by that suitable equipment is chosen.

Ex‐areas requires increased safety and high sealing classes.

Thermostat/limiter used in hazardous areas can be designed in different ways:

1. Mechanical thermostats

2. Electronically thermostats

3. Regulators

1.Mechanical thermostats

Mechanical thermostats use the expansion in fluid included in a bulb, which is transferred via a capillary tube to a membrane, which influence the electrical contact of the thermostat. The capillary tube has often a max. length of approx. 3 meter.

2. Electronical thermostats

An electronic circuit influence a relay which control the heating cable directly or via a contactor (at loads over 2 kW, a contactor is normally required). The electronic circuit is connected to a temperature sensor (NTC, PT‐100 or thermocouple) in a low‐tension connection (as a rule 6‐12V) and to these there is zener barriers available when the transmitter is placed in a Ex‐area.

The advantages with these thermostats compared to capillary thermostats are partly that on large distances and those electronical thermostats most often has a larger precision.

Electronical thermostats can be obtained with a couple of extra refinements such as alarm, adjustable after‐effects, temperature reading etc.

3 RegulatorsThe regulators are the most advanced form of control system. They are built upon the same principals as the electronical thermostats but here you can chose time proportional control via solidstate‐relays which is of advantage in soft starts etc. Memory based functions to avoid overshoot at start etc.

Regulators is also available with several channels and with external connection to a computer for example, where reading and set‐up can be managed from optional place on earth (where a operating thread/mobile telephone is available) via a modem.

Such a function can give great benefits at for example an unmanned depot for thick oil where the heat on loading shall be connected a couple of days before loading from incoming boat can be done. Here is often possibilities to connection of all types of transmitters which can be of a great advantage at reparation of old applications where existing transmitters are difficult to reach. Värmekabelteknik have a complete program from VärmeKabelTeknik with advanced products for the industry.

Control – Parallel resistive heating cables

The output of the parallel resistive cables are independent of the temperature, they can of that reason no be temperature rated. Parallel resistive cables shall therefore always be equipped with a overheating protection, for example a thermostat which in the same time can control the operating temperature. Each circuit is supplied with at least one thermostat.

Parallel resistive cables have no general approval for Ex‐surfaces and exemption must be applied for each application.

Control – Self- l imiting heating cables

The self‐limiting cables have in the EX‐approval been supplied with a T‐Class, which states the maximum sheath temperature the cable can accept during all circumstances.

Cables with a semiconductor core reduces its output with rising temperature but this does not mean that the cable control an application temperature. Heating cables never comes down to an output of 0 W and this means to be able to maintain a required temperature on a piping, a control device should be supplied.

The control device can consist of a thermostat or a regulator with a temperature transmitter mounted against the heated object.


31

Chapter 7 Control and Alarm

Control – series resistive heating cables

All series resistive cables require a thermostat. The need is equal with parallel resistive cables.

Placement of the thermostat transmitter

Thermostats can be used in different ways, as already been determined:

‐ To maintain a pre‐set temperature

‐ Switch on/off frost protection functions

‐ As overheating protection (limit the sheath temperature on a cable in Ex‐applications or to protect the cable against overheating).

‐ To protect applications (plastic material).

‐ To protect temperature sensitive products.

The process of flow the pipe‐system, lengths with in‐/outdoor length and high risings with chimney effect, which as consequence is important details to determine the placement of the temperature transmitter.

Plan the application

In a system with varying ambient temperatures, large risings and many branchings or if the temperature is close the upper limit for the max. temperature of the cable, it can be suitable to divide the application with separate cables and temperature transmitters for each reference area, respectively.

When designing a heating cable application one must consider to some parts of the pipe system such as expansion vessels, fillings and drainage’s not have part in the normal circulation in the system. This brings you to supply these branchings with a separate circuit with a separate temperature control.

The reason is when operating the other system, heat is spread with the circulating fluid, while de above mentioned parts has a not moving content and is not influenced by supplementary heat from processes etc.

Self- l imiting cable

At such applications can the number of thermostats be held down if using self‐limiting heating cables since this cable reduces it’s output at rising temperatures, which eliminates the risk of overheating.

Self- l imiting cable

Direction of flow

In an application as in the sketch below, the transmitter shall be mounted near the heated tank in order to break from feeding to the heating cable at the percolation from the tank to protect against overheating.

Control cabinets

VÄRMEKABELTEKNIK offers a large assortment of control cabinets in standard designs. We construct and also build special cabinets after your requirements and specifications.

The standard cabinets are available with electronic thermostat and ice‐/snow alarms for –roofs and ground surfaces.

Special cabinets can be supplied with communication possibilities for DUC, alarm senders, alarm functions for earth faults, released fuse current sensing alarm or another special function. Control can be done with thermostat, simple or with multi‐channel regulator with or without telecommunication via PC.


Chapter 8 Installation and Thermal insulation

Thermal insulation and installation

To obtain a well functioning application, a good insulation is required. As already been mentioned, we compensate the heat loss through the insulation by supplying heat. A poor insulation gives an application with defective function and a bad operating economy. Here are some tips that can improve the insulation:

* The controller of the vents shall be supplied with plastic insulation against openings in the insulation sheath, downward openings in shall be sealed with sealing compound.

* Most of the insulation material is hygroscopic. Insulation material with closed cell structure (foam) is not hygroscopic, but have in general a lower operating temperature, max. +100°C.Therefore choose insulation with closed cell structure if the temperature admits it.

* Conduit entries through the insulation are carried out on the underside of the pie, if possible, so they are protected against moisture.

* Vents and flanges etc, has a larger diameter than the pipe. Of this reason shall the heating cable be installed with an extra coiling at those and to be extra careful so that the insulation not get thin to give a straight and facilitated outer sheath. Another advantage with extra cables at vents is when these have to be dismounted at leakage and a extended cable must be cut.

If cable of self‐limiting type is used the emitted output is reduced if the cable don’t have or have poor contact with the object which are to be heated.

Heating cables shall always be covered with aluminium tape or aluminium foil before insulation. This in order to secure the fit‐up of the heating cable against the object and to avoid that the heating cable (due to movements in the application and heating cable), is covered with insulation with cable rupture or poor heat transfer as a result.

At applications with self‐limiting heating cable the output curves presented for the heating cable presumes that installation is done with aluminium tape or foil.

The insulation around pumps and small vessels must be fixed so that it does not came loose (insulation support is welded on the outside of the tank wall).

Passage for leading‐in of connection cables to heating cables and transmitters, are best done from the underside of the pipe when risk of moisture penetrating is nearly non‐existent.

Important general instructions

These instructions must be followed at installations of VärmeKabelTeknik’s industrial cables on pipes. VärmeKabelTeknik’s heating cables are available in three basic types: Self‐limiting, parallel resistive and series resistive. Below you will find a table, which shows some of the characteristics which separate the cable from VärmeKabelTeknik from each other.

Self‐limiting Parallel Series resistive resistive Applicable in Ex‐zone Yes No1 No1 Applicable on plastic pipes yes Yes2 Yes4 Can be cut in lengths on site Yes Yes No Protects against overheating Yes No No Can be installed in long lengths No Yes Yes Max. temperature °C 2005 2005 600

1 Exemption can be applied for specific applications 2 With outputs up to 12W/m 3 Emitted output is reduced with rising temperature 4 Can be dimensioned with low outputs/running meter 5 With the supply voltage switched off


33


Control of delivered material

1. Open the package and control by hand after ruptures or damages on the sheath of the cable. Report immediately if any damages been discovered and keep the package (Reclamation to the transport business).

2. Never connect the heating cable to the supply voltage when it is coiled or on drum.

3. Control after installation the insulation resistance with a 500VDC megger in order to ensure that the cables have not been damaged during transport and handling. WARNING: cables with an insulation resistance smaller than 10 megaohms insulation resistance can be defect (contact your supplier!)

4. The heating cables shall be stored in their package or on drums in a dry environment until the installation. The heating cables should be kept in surfaces with temperatures over 0°C, at least 2‐3 days before installation in order to prevent damages on the insulation material at installation.

Important regarding installation of heating cables

1. Installation and installation material shall meet electrical standards and be installed by authorised personnel. Read this instruction sheet to be acquainted with the products.

2. Always use the same manufacture on mounting kits as for the heating cable. Always follow the enclosed instructions at mounting of installation accessories.

3. When applications are carried out in explosive areas must junction boxes and other connecting material be consistent with the Ex‐class for the area.

4. Make sure that all pipes, tanks etc, have been tested hydrostatic before installation of heating cable.

5. Always install the heating cable with position “five a clock or seven on a pipe.

6. OBSERVE! All heating cable applications require some form of thermal insulation to be able to supply heat to an object.

7. Do not install heating cable on equipment, which gets warmer than the maximum exposure temperature of the cable.

8. Do not install heating cables on a surface or on equipment containing potential caustic material without suitable outer sheath on the cable.

9. Don’t be below the stated minimum bending radius for the heating cable.

10.At installations with more than one cable run or spiral winding of self‐limiting cables where the distance between the cables will be lesser than 50mm, can interference between the cables influence the emitted output negatively in relation to the recorded value in the output table.

11. Always install heating cable on the outer radius on elbows to obtain sufficient power.

12.Never install the heating cable above expansion joints with giving the heating cable drift space, see figure on page 49.

13.Never use binders or clamps which can damage the outer sheath to fix heating cables. (Exceptions can be done at mineral insulated cables).

14.Pumps and small vessels which are provided with heating cable and temperature control, shall the temperature transmitter be mounted at inlet. The cable on the pump/vessel should be physically separated from connecting piping cables in order to admit dismounting of pump/vessel.

15.Always cover the heating cable with aluminium‐tape/foil in order to improve dissipation of heat from the heating cable against the object and to avoid that the cable is pressed into the insulation material.

16.Longer stirring stick and parts of system with divergent percolation or dimensions should, if –possible, be provided with separate control and heating length. Also consider that a “nude”couple on the conductor must be compensated with an extra heating cable.

17.Take into consideration the chimney effects and heat variations in media at heavy risings in a pipe system. To avoid negative efficiencies, a separate control and heating length is installed.

18.Take into consideration the stated lowest installation temperature at mounting in the data sheet.

19.If the application contain temperature sensitive pipe material (for example plastic) or if the application include temperature sensitive substances, take this into consideration when choosing cable and dimensioning. Contact the supplier for advice.

B. Installation instruction for heating cable with a single length along a pipe

1. Fix the cable end at the pipe and put the cable reel on a holder. Reel out the cable so that it doesn’t turns or that loops are formed.



2. Ensure that the cable follows the pipe when crossing obstacles. For example, an upright or a pipe support which passes or when pipes cross each other.

WARNING: Be careful to avoid things as:

‐ pull the cable over sharp edges. ‐ pull the cable free with violence if it get caught

while it is installed. ‐ Handle the heating cable so that it gets damaged

mechanically, for example by smash or walking traffic. Consider that other contractors taking part in the same application maybe is without knowledge about the nature of electrical material.

3. When reaching the end of the circuit, secure the heating cable against the pipe by using a glass fibre tape or another material corresponding to the requirements of the application.

4. (If the heating cable shall be spiral winded, go to step 4A.). Begin to fix the cable against the pipe every three‐meter. Place the cable on the lower half of the pipe at the placement “5 or 7 a clock”.

4A Spiral winding of the heating cable . An easy way to handle the spiraling factor is: A1.1

spiral factor means install 1,1m heating cable every meter of the pipe. Then begin to mark the pipe in sections of 3 meter, measure of 3m x spiraling factor and fix this point at the first 3 meter mark and let the cable hang down under the pipe, repeat until the whole length of the pipe is laid.

4B Grasp in the middle of the hanging heating cable and wind the cable on the pipe. Fix the middle point with glass fabric tape and level out the cable so that it obtains an even distribution and a good fix‐up against the pipe. Fix with a distance of one meter.

5. At details that requires extra supply of heat (pipe supports, vents, pumps, restrictions etc.). Fix the heating cable against the pipe exactly before the detail. Refer to sketches to determine the amount of cables you shall install on the detail. Pull this cable to a loop, attach the heating cable on the other side of the detail and continue to fix the cable down against the pipe as before.

6. Fix the heating cable in regular intervals along the pipe and distribute and fix the cable against details. Make sure that approx. 20cm heating cable stretches out where the end termination shall be carried out and sufficient heating cable length to carry out a connection end and connect to junction box.

7. It is important with enough amount of heating cable on vents, flanges etc. Use your judgement to determine if the detail can be dismounted without damage the heating application.

‐ Self‐limiting heating cables are very flexible and can be overlapped to facilitate the installation.

WARNING: Do never cross parallel resistive or series resistive heating cables.

‐ By installing self‐limiting heating cable in this way, it can easily be removed from the detail to undertake repairs or modifications in the pipe application without damage the heating cable application.

Installation of more than one heating cable on a pipe length

There are different reasons for installing more than one heating cable on a pipe.

‐ At larger pipe dimensions and/or to manage the required power of a pipe.

‐ When building a system where all functions is of such importance that you choose to install a spare cable as back‐up.

There are several procedures. One is to use two or more heating cable reels and feet one cable from each. This method works for all type of pipings. The disadvantage with this method is that it can increase material waste by leaving useless lengths from two reels. The other way is to feed both cables from one reel. This method is normally the easiest for a straight, simple tubing.

A. Feed the cable from two reels.

1. At each detail where extra heating cable shall be mounted, the easiest way is to do this from only one heating cable.

2. At pumps and flanges and other places where dismounting can be necessary, must extra cable be left from all lengths.

3.a INSTALLATION OF SEVERAL HEATING CABLE FROM ONE REEL

Is carried out in the same way as above but here the cable must be cut to lay the other run, which requires that you have ensured extra cable for details and connection‐/end termination ends before cutting.

NOTE! When you reached the end of the pipe, take some extra cable for connection‐ and end termination, which shall be mounted and carried out.


35


B. Installation with back-up-length

The purpose with a back‐up system is that each cable can emit sufficient with output for a normal function even if one of the cables should fail. Therefore must each cable be installed so that it covers the whole application.

IMPORTANT TO THINK ON BEFORE YOU ORDER!

On pipes with smaller diameter than 25mm it can be difficult to attach two heating cables with good contact against the pipe. Choose a cable with higher power/m or increase the thickness of the insulation as compensation.

4. All equipment must be earthed.

Control

1. All heating cable circuits shall be equipped with temperature control in form of thermostats or regulators. At high outputs or temperatures near the heating cable/heated medias max. temperature, shall each circuit be supplied with separate control at pipings with long, vertical risings with risk of overheating as a result of the “chimney effect”.

2. Contactors must be used when the current in the circuit exceeds the stated current for the thermostat. Observe that when the application is carried out with self‐limiting heating cable must consideration be taken to start currents (see data sheet).

3. The control equipment shall be installed so that it not is exposed for vibrations and as far as possible tempered surface to avoid hot well.

4. Conductive sensitive temperature transmitters shall be mounted in accordance to the instructions.

5. Ambient temperature transmitters shall be placed at a point, which can be considered as typical for the connected application. Take consideration to heat leakage and solar radiation.

6. Capillary thermostats shall be mounted protected in a box on the pipe. Observe that the capillary must be protected mechanically.

WARNING: Handle the body of the thermostat and capillary with care. Rotary damages and folds can destroy the accuracy of the thermostat.

Control after installation

When heating cable application and connections for a circuit is ready, then immediately carry out following controls:

1. Inspect the heating cable and temperature controls by hand after marks of mechanical damages. If a damage is found, the whole cable should be replaced or cut out the damaged part and joint the cable with help of a jointing kit from the cable supplier.

2. Control connections and inlet nipples and that closing cover of the box are correctly sealed.

Measure the insulation resistance with a 5000V megger. All cables with an insulation resistance less than 10 megaohm shall be removed and discarded.

4. Vents and flanges, pipe supports and the like, requires more heat than the other pipe and therefore requires, if this is not compensated with extra heating cable, thicker insulation.

5. If using a metallic sheath and screw, be sure that the screws not are so long that they can pierce through the insulation and damage the heating cable.


Chapter 8 Installation and Thermal insulation Installation examples

Positioning and attachment of heating element Spiral installation of heating element

NOTES.

1. If ratio of heater footage to pipe is greater than 1.5 – use two parallel heaters or select higher wattage heater. If ratio is less than 1.0 – use one parallel heater.

1. When installing the heater on non-metal pipe secure the heater to the pipe with aluminium tape. Refer to pitch chart on isometric drawings for proper pitch length.

Power connection kit/Mounting detail/Ordinary and hazardeous areas

Heating element termination

NOTES

1. For more specific details and full materials list refer to installation instruction sheet packed with connection kit.

Thermostat sensor positioning and attachment on tanks Positioning and attachment of thermostat sensor on pipe


37


Heat tracing of fittings, valves and process equipment

Notes: This detail is shown as an illustration of a method of taking advantage of the shape of a piping configuration to attain good pipe contact. To simply trace the inside radius of the corner would not be considered correct. Although a tee-splice might also be used to trace the third leg of the tee. The objective of this detail is to emphasize that it is advisable to get more heater on any area where the thermal insulation might not be fitted as well as on straight pipe. This method is intended to be used on other fittings besides tees.

Notes.

1. Exact configuration may vary per valve type.

2. For removable valve bodies leave a loop of tracing of the proper length when tracing the pipe.

3. See installation chart for correct amount of tracing per valve size.

4. Take care to keep the flat side of the heater in as good physical contact with the valve body as possible.

5. Fully insulate and weather protect.



Heat tracing of fittings, valves and process equipment

NOTES

1. See National Electrical Code paragraph 427‐12(E).

2. Fully insulate and weatherproof (if outdoors).

Heat tracing around pipe supports

NOTES All forms of rigid pipe supports directly in contact with the pipe surface act as a heat sink. Heat tracing should be doubled over at these points and the supports should be insulated as much as practicable to limit heat loss.


39


Heat tracing of line mounted instruments

NOTES Treat turbine flow meter as a valve of the same pipe diameter. Leave a loop of material the same as for a valve.



Heat tracing of line mounted instruments

Notes:

1. Fully insulate and weatherproof. 2. Exact configuration may vary. 3. refer to installation isometrics for proper tracer type

and amount. 4. Where the heater is applied in the region designated

as “Bolt Area” aluminium tape should be used to aid heat transfer because of the excessively irregular surface.


41

Chapter 8 Installation and Thermal insulation Start‐up of the application

1. Once again inspect by hand the conduits and connections for the heating cable, to be certain that no mechanical damage have occurred if some time have passed between the installation and the start‐up.

2. Insulate test the system in order to determine that no earth faults occurred as a result of mechanical damage.

For application with thermostat feeling the ambient temperature:

1 If the temperature is higher than the set‐up of the thermostat, change the set‐up to sufficient high for switch.

2. Switch on the main circuit breaker.

3. Switch on the operating breaker one by one until every on is on.

4. Run the system at least four hours to let all pipes reach the operating temperature.

5. Measure the current value, ambient temperature and pipe temperature for each circuit and write it down in the installation protocol. This information can be needed for future maintainances and location of faults.

6. When the system is totally checked, reset the thermostat to prescribed value.

For system which have been supplied with fit‐up transmitter:

1. Set the required temperature on the thermostat.

2. Switch on the main circuit breaker.

3. Switch on the operating breaker one by one until everyone is on.

4. Allow the pipe temperature to increase to operating temperature. This can take 5‐10 hours (large, full tanks can take longer time).

5. Measure the current value, ambient temperature and pipe temperature for each circuit and write it down in the installation protocol. This information can be needed for future maintenance and location of faults


Chapter 8 Installation and Thermal insulation Maintenance protocol

Reference information

Circuit number

Fuse number

Drawing number

Circuit length

Visual inspection of heating cable length

No signs of moisture, or rust formation Initial

Date

Correct electrical connections Initial

Date

Correct earthing Initial

Date

Electrical control of heating cable length

Megaohm test (500V)

(bypass‐control)

Meg ohms

Date

Current measurement (self‐limiting cable at operating temperature)

Compare with mark sign or electrical drawing

Ampere

Amb.temp

Date

Control of the resistance of the length Resistance

Date

Control/Temperature transmittor

Temperature control, correctly settled Set point

Date

Transmitter in function Initial

Date

Sealings and junction boxes, intact Initial

Date

Control of thermal insulation

Passages in the outer sheath of the insulation, intact Initial

Date

The insulation is complete, dry and protected for the weather Initial

Date


43

Chapter 8 Installation and Thermal insulation Fastening material

E89 992 36 Glass fabric tape E89 992 44 Aluminium tape Hose clamp

Clamp Kit E89 992 38 (Band)‐39 (lock) Expediter (pipe support) with junction box E8999262 (Ryton)‐64 (ABS)

E89 992 60 Junction box

Termostats

Capillary thermostats Electronic thermostats Regulators Termination materials

89 892 50 Connection kit SRL/SRM 89 992 52 Connection kit SRL‐CR 899 892 54 End termination SRL/CRM‐CT


Telephone: +46‐301‐418 40 – Email: [email protected] – Homepage: www.vkts.se

Industrihuset Södra Hedensbyn 43

S‐430 64 HÄLLINGSJÖ S‐931 91 SKELLEFTEÅ

Sweden Sweden

Fax: +46‐301‐418 70 Fax: +46‐910‐881 33

industrial heating

Documents