erhard control valves · for this purpose, control valves are operated in intermediate positions....

ERHARD Control Valves

Control valves are essential for guaranteeing safety in pipe networks and sys-tems, and adapting pressure, flow or water level to current requirements and draw-off. They ensure that the desired water quantity is always available to con-sumers in private households or businesses, and at the same time they protect the pipe network reliably from damage caused by excessive pressure values or water hammers. This means they also contribute to economic operation, since expensive water losses are restricted and the water supply oriented towards demand.

For this purpose, control valves are operated in intermediate positions. Gate valves and butterfly valves, which are simply open / close valves, are not suitable for control tasks, because turbulence and cavitation can occur if they are only partly opened. In the case of control valves, the destructive effects of cavitation are minimised by the design, avoiding damage to the valve and to the following pipe. In addition, a low-vibration and quiet energy conversion prevents damage to buildings and pipeline.

The perfect solution for every area of applicationThanks to decades of experience, the company’s own testing facility and a wide range of products, ERHARD is an expert partner in the field of control valves. Numerous points need to be taken into consideration for the correct design of control valves in particular, in order to select the right product in the right size:•Which control task has to be performed? Is pressure to be reduced? Is tank

supply to be controlled? Or does a pump need triggering properly?

3 ERHARD Control Valves

•What are the operating conditions with regard to upstream and downstream pressure or flow?

•What is the installation situation?•Which actuator options are suitable?•And how is the system to be controlled?

It is very important for all control valves that they have to be designed according the flow quantities and upstream and downstream pressure, not according to the nominal pipe size.

Types of control valvesA basic distinction is made between two types of control valves:•Control valves controlled by external energy are actuated electrically, pneu-

matically, hydraulically or manually. In the case of electric or pneumatic actuators, they are often combined with respective control technology which controls the opening of the valve on the basis of the current pressure or flow values. The ERHARD REV control valve [1] is an example of this type of valve (page 4).

•In contrast, process-medium operated control valves acquire their actua-tion energy from the flow medium. For one thing, they are available without pre-control, e.g. the ERHARD DVF pressure reducing valve [2], where pres-sure reduction can simply be adjusted manually using a spring (page 8). For another, process-medium operated control valves can also be equipped with a pre-control. This is often known as a pilot control and allows very precise and finely adjusted control as well as the integration of various control options e.g. for professional pressure management. The combination of various pilot attachments with the valve stem results in variants for numerous tasks from pressure reduction [3] to tank level regulation [4] (page 12).

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ERHARD REV ConTRol VAlVE The valve with the sensitive slot controlThe ERHARD REV control valve is the ideal solution for all throttling and regula-tion tasks in nominal sizes DN 50 to DN 150. The main component is the fixed slotted bush in which the control piston is moved and covers or releases the slot areas depending on the control position. Thanks to this design and optimised flow behaviour, the energy conversion which occurs takes place with very little load on the materials and minimum noise development. Turbulence and cavita-tion do not occur until downstream from the control piston, in the stainless steel stilling chamber. At the same time, counterpressure is built up by diverting the flow. This means that the ERHARD REV control valve is excellently suitable for permanent operation under cavitation, and takes for small pipe sizes the tasks covered by needle valves in larger pipe sizes.

The other design characteristics have also been proving their worth for years:•The control piston is guided in durable slip rings made of PTFE.•A valve seat integrated in the housing and sealed with an O-ring guarantees

bubble-free sealing. The seal is outside the flow and cavitation area.•The control piston is connected axially to the valve spindle without clearance.•In the standard version, the valve is equipped with a mechanical position

indicator.•The final closing position of the stroke is restricted by a fixed stop.•It is always possible to replace the slotted bush and the piston on the valve

without having to remove the valve from the pipeline.

Wide range of application areasThe ERHARD REV control valve is used particularly where flexible control is nec-essary. In conjunction with electronic controllers, pressure gauges, flow meters or float switches, it can be used on the one hand as a pressure regulators for a constant or flexible downstream pressure or for regulating quantity for a con-stant flow. The sensitive slot control permits start-up with very little water ham-mer, which makes the ERHARD REV control valve suitable as a bypass valve, for tank supply control or as a pump pressure valve.

Slotted bush and control piston guarantee energy conversion does not cause any damage, even under cavitation


no. Advantage Property

1 Safe energy conversion with good control characteristics

Design with sturdy slotted bush, graduated control slots and long piston guide

2 Sturdy and insensitive for a long service life

FBE coating for optimum corrosion protection, internal parts and bolts made of stainless steel

3 Permanently safe sealing Piston seal made of PFTE and elastomer outside the flow and cavitation area

4 Maintenance-friendly The internal parts can be replaced without having to remove the valve from the pipe

5 User-friendly Position indicator as standard

6 Straightforward conversion to other actuators

Modular principle for changing between handwheel, electric actuator or hydraulic or pneumatic actuator, even with the valve installed

PRoPERTiEs AnD ADVAnTAgEsAT A glAnCE

4

2

6

5

1

3


FlExiblE UsE, ACCURATE DEsignThe ERHARD REV control valve is available both with a straight pattern and an angle pattern body, allowing it to be integrated in every installation situation. Thanks to the modular principle, the valve can also be equipped with different actuator options:•Handwheel•Electric actuator•Hydraulic or pneumatic piston actuator

Conversion is possible at any time – even with the valve installed, which means that the system can be adapted to changing requirements and modified control technologies at any time.

Determination of pipe sizeUnlike with other fittings, the correct valve size is not selected according to the pipe diameter but rather on the basis of the maximum flow and the installation situation:

nominal size Dn 50 65 80 100 125 150KVS (m3/h) 36 59 87 140 210 280Zeta 7,6 8,1 8,5 7,8 8,7 10,2Qnormal (m3/h) 11-28 18-47 27-72 43-113 65-175 97-255hV at Qnormal (mWS) 0,9-8,5Qmax (m3/h) 42 70 108 170 265 380hV Qmax (mWS) 14-19KV min (m3/h) 1,2 1,2 1,2 1,5 1,5 1,5

Values used

KVs: The KVS value specifies the flow in m3/h of water at 5 to 30 °C which passes through the completely opened valve at a pressure loss of 1 bar.

Zeta: Pressure loss coefficient with valve fully opened

Qnormal: Volume flow corresponding to a flow speed of 1.5 - 4 m/s with regard to the pipe size

hV: Pressure loss with valve fully opened

Qmax: Maximum permissible volume flow for short-term operation, corresponding to a flow speed of 6 m/s with regard to the nominal size

KV min: Controllable, smallest volume flow with a differential pressure of 1 bar for water. With a prescribed differential pressure Δp the smallest volume flow is

Qmin. = KV min · √Δp [m3/h] (Δp in bar)

100

10-3

10-2

10-1

100 DN50

DN65

DN80

DN10

0DN

125

DN15

0

101 102

Medium:Wasser20° C

2 3 4 5

2

3

456789

2

3

456789

2

3

456789

56789

6 7 8 9 2 3 4 5 6 7 8 9 2 3 4

Flow volume (m³/h)

Pres

sure

loss

Δp

(bar

) in

fully

ope

ned

valve


brief specifications for materials and equipment•body: Spheroidal cast iron EN-JS1050•Cover flange: Stainless steel•Vertical column: Spheroidal cast iron EN-JS1050•slotted bush, body seat, piston, spindle and spindle passage: Stainless steel•Threaded bush: Special brass•Pointer: Brass•seals: Elastomer•Corrosion protection of the body parts: Internal and external fusion bonded

epoxy (FBE) coating in blue

size Dn

Pressure reating

Pn

Face-to-face dim.

l mm

Face-to-face dim.

s mm

Height H1

mm

Height H2

mm

Diame-ter D

Rotation per hub

Weight with

hand-wheel

50 16 230 150 285 380 165 8,0 2850 25 230 150 285 380 165 8,0 2850 40 230 150 285 380 165 8,0 2865 16 290 165 290 385 185 9,5 3665 25 290 165 290 385 185 9,5 3665 40 290 165 290 385 185 9,5 3680 16 310 180 310 400 200 10,5 4580 25 310 180 310 400 200 10,5 4580 40 310 180 310 400 200 10,5 45

100 16 350 200 330 420 220 12,5 59100 25 350 200 330 420 235 12,5 59100 40 350 200 330 420 235 12,5 59125 16 400 225 355 445 250 14,5 80125 25 400 225 355 445 270 14,5 80125 40 400 225 355 445 270 14,5 80150 16 480 250 385 475 285 17,0 112150 25 480 250 385 475 300 17,0 112150 40 480 250 385 475 300 17,0 112

Area of application: Watersize Dn

Pressure rating Pn

Hydrostatic test pressure (bar) Max. allow. gauge working pressure in bar at +40 °Cbody seat

50 - 150 16 25,0 17,6 16,050 - 150 25 37,5 27,5 25,050 - 150 40 60,0 44,0 40,0


ERHARD DVF PREssURE REDUCing VAlVE

1 Setting screw2 Spring3 Mobile unit with spindle and piston

guide, spacer, valve disk, diaphragms and sealing ring

4 Valve seat

The directly controlled pressure reducing valveThe task of the ERHARD DVF pressure reducing valve is to convert a higher, fluctuating upstream pressure into a lower, constant downstream pressure. The respective downstream pressure required is set by pre-tensioning a spring. There are two types of spring available for the ERHARD DVF pressure reducing valve: spring A (blue) for a pressure range from 1.5 to 6 bar and spring B (red) for a pressure range between 5 and 12 bar. This means that a large downstream pressure range can be covered with only one valve which can also be adapted to later requirements.

Whereas the upstream pressure has no influence on the control function, since all moving parts are pressure compensated with regard to the upstream pressure, the downstream pressure which acts on the lower valve disk surface works against the pre-tensioned spring. If the downstream pressure falls below the set value, the valve opens, if it rises above the value, the valve closes again. If there is a balance between the force on the valve disk and the spring force, the valve is in an intermediate position. If there is no flow into or out of the pipe, the control valve closes, which means it takes over an OPEN-CLOSE function in addition to the control function.

The robust design of the ERHARD DVF pressure reducing valve permits safe operation at all times:•The guide pistons are outside the medium, excluding coating formation and

avoiding the risk of blockages.•Stable rolling diaphragms ensure friction and delay-free function.•All internal parts are accessible from above, making servicing easier. In addi-

tion, no special tools are necessary for servicing.•Two integrated pressure gauges with isolating valves allow user-friendly set-

ting and monitoring of the function. •High-grade materials and an FBE coating guarantee a long service life.•Control is carried out exclusively by the flow medium, external energy is not

necessary. This allows the valve to be be set up even in places where there is no power supply.

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1 Reliable function without blockage risk

Guide piston outside the medium, thus preventing coating formation

2 Friction and delay-free pressure reduction

Stable rolling diaphragms

3 Covers a large downstream pressure range

Downstream pressure can be adjusted to between 1.5 and 6 bar or 5 and 12 bar thanks to two different spring types


All FBE coating for optimum corrosion protection and high-grade materials

5 Maintenance-friendly All internal parts accessible from above without additional special tools being necessary

6 User-friendly Version with two metres with isolating valves

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3

5

1

2

4

11 10 ERHARD Control Valves

With ERHARD DVF pressure reducing valve the valve size is not selected accord-ing to the pipeline diameter either, but rather depending on the maximum flow quantity Qmax. The following assignments apply

For use in fire extinguishing applications, speeds of up to 4 m/s are permitted for short periods.

Using the nominal size selected as a basis, it can be checked whether the given data can be covered with the valve without getting into the cavitation area. One example:•There is an upstream pressure of 12 bar which is to be reduced to a down-

stream pressure of 6 bar.•The flow quantity to be managed is 13 l/s, so the nominal size chosen is

DN 100.•A check based on the diagram confirms that the working point is in area 1 and

thus no cavitation will occur.

Testing the valve’s cavitation behaviour:• Field 1: Normal function without cavitation• Field 2: The differential pressure is too high,

cavitation occurs. If appropriate, two valves can be arranged behind each other.

• Field 3: Outside the permissible area of application

• Field 4: Physically impossible, since the upstream pressure can never be smaller than the downstream pressure.Up

stre

am p

ress

ure

(bar

)

Downstream pressure (bar)

2

2

4

4

6

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8

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10

12

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Case Dn 50 65 80 100 125 150 200A < 3 bar V = 2 m/s Qmax in l/s 4,0 6,6 10,1 15,7 24,5 35,3 62,8

Qmax in m3/h 14,4 23,8 36,4 56,5 88,2 127,1 226,1B > 3 bar V = 3 m/s Qmax in l/s 5,9 10,0 15,0 23,6 36,8 53,0 94,1

Qmax in m3/h 21,2 36,0 48,0 85,0 132,5 190,8 338,8

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4

3

2


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brief specifications for materials and equipment•body and bonnet: Spheroidal cast iron EN-JS1040•Plug: Lamellar cast iron EN-JL1040•body seat and guide: Alu-bronze•sealing ring: Polyurethane•setting screw and guide rod: Stainless steel•spring: Spring steel, varnished•Rolling diaphragm: Neoprene with fabric ply•Corrosion protection: Fusion bonded epoxy (FBE) coating in blue•Pressure gauges with isolating valves: On the upstream and downstream

side•Mounting lever: Included in the scope of supply

L

D

size Dn

Pressure rating

Pn

Face-to-face dim.

l mm

Flange diam. D mm

Height h1

mm

Height h2

mm

Weight kg

50 10 / 16 230 165 430 90 1950 25 230 165 430 90 1965 10 / 16 290 185 420 100 2565 25 290 185 420 100 2580 10 / 16 310 200 450 115 2980 25 310 200 450 115 29

100 10 / 16 350 220 450 115 32100 25 350 235 450 115 32125 10 / 16 400 250 550 145 61125 25 400 270 550 145 61150 10 / 16 480 285 550 145 66150 25 480 300 550 145 66200 10 / 16 600 340 605 190 117


Pressure rating Pn

Hydrostatic test pressure (bar) Max. allow. gauge working pressure in bar at +60 °Cspring A spring b

200 10 1,5 - 6,0 5,0 - 12 10,050 - 200 16 1,5 - 6,0 5,0 - 12 16,050 - 200 25 1,5 - 6,0 5,0 - 12 25,0


ERHARD ConTRol VAlVEs WiTH PRoCEss-MEDiUM AnD PRE-ConTRolThe precise control valve for a wide range of application areasPre-controlled control valves from ERHARD are made up of two components – the main valve identical for all variants and the task-specific control unit.

The main valve comprises a sturdy body made of cast iron, a bonnet, a plug with a respective guide, a diaphragm made of elastomer and the position indicator. When unpressurised, the main valve is always closed on account of the force of the internal spring and the plug’s intrinsic weight. The main valve contains three chambers which are decisive for valve control:•Chamber A with upstream pressure•Chamber B with downstream pressure•Chamber C with control pressure

The three chambers are mutually connected via the control unit. This is made up of the orifice [1], the upstream pressure line [2], the pre-control valve, also known as the pilot valve [3], the downstream pressure line [4] and finally the throttle valve or the throttle insert [5].

This design results in the following basic function, with the pre-control valve shown as a valve with hand lever in the diagram: •During closing [6] the upstream pressure from chamber A reaches control

chamber C. The main valve closes.•The valve opens [7] when the upstream pressure from chamber does not reach

the control chamber and the pressure can flow out of the control chamber.•The valve blocks [8] if the control pressure is trapped in the control chamber.

In the case of a pressure reducing valve, where the objective is to achieve a reduced and constant downstream pressure, practical implementation is as follows: if downstream pressure increases, the pilot valve closes. Then water flows from the upstream pressure side into the control chamber and the main valve closes as well. In contrast, if the downstream pressure falls, the pilot valve opens and the water can flow out of the control chamber, leading to the main valve opening.

6 7 8

A

2

3

5

1

4

B

C




1 Sturdy control function for many tasks

Design with main valve and precisely controlling and task-specific control valve

2 No wear Seat is outside the cavitation zone

3 Maximum flow capacity and economy

Little pressure loss when the valve is opened completely


All-round FBE coating for optimum corrosion protection and high-grade materials

5 Maintenance-friendly All internal parts accessible from above without additional special tools being necessary. Control unit can be serviced without having to shut down the main valve

6 User-friendly Equipped with two pressure gauges with isolating valves as position indicator

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2

1

3

4

5


The main valve then reliably corrects the pressure and keeps the hydraulic parameters almost constant by taking over the pilot valve state – closed, open, middle position.

This enables the control valves of this product series to take over numerous different tasks in practical use:•for flow control as pipe burst safety valves or flow regulators•for regulating pressure as pressure reducing valves, pressure sustaining

valves or differential pressure limiting valves•for regulating filling levels as level control valves or float valves

In addition, multiple functions can be achieved by using different pilot valves connected to one control line.

The design is not dependent on the pipeline diameter for pre-controlled con-trol valves either, but rather depends on the required flow quantities and the respective application case (see page 16/17).

The optional anti cavitation insert is based on two slotted cylinders which proved their value in ERHARD needle valves. It reliably protects from cavitation damages in case of high pressure difference and small openings as well as in case of high flow volumes at fully opened valves.


14

Well thought-out design, top material qualitiesAll pre-controlled ERHARD control valves are designs which have been in tried-and-trusted use for years, with well thought-out details and top material quality:•Body and hood are made of sturdy cast iron EN-JS1040.•The seat is outside the cavitation zone, thus minimising wear.•All the valves can cover a large pressure range e.g. a downstream pressure

range from 1 to 20 bar when used as pressure reducing valves.•There is minimum pressure loss when the valve is completely opened, which

allows a very high flow capacity so that these valves can even handle flow volumes that are required for fire-fighting applications.

•All the internal parts are accessible from above, so that servicing work is pos-sible without the valve having to be removed from the pipeline.

•Two integrated pressure gauges with isolating valve permit permanent moni-toring of the function.

•Valve control is carried out exclusively by the flow medium, no external energy is required. This means valve operation does not require a power supply.

brief specifications for materials and equipment•body and bonnet: Spheroidal cast iron EN-JS1040•Plug upper and lower section and clamping ring: Lamellar cast iron

EN-JL1040•body seat ring and guide: Bronze•sealing ring: EPDM•screw and guide rod: Stainless steel•Position indicator: Stainless steel / bronze•Pre-control valve: Bronze / elastomer•Control unit and fittings: Stainless steel•Diaphragm: Neoprene with fabric ply•Corrosion protection: Internal and external fusion bonded epoxy (FBE) coating


ERHARD DVP4 Pressure Reducing Valve This valve is used for converting a fluctuating, higher upstream pressure into a lower, constant downstream pressure. The reduction is independent of fluctua-tions in flow, a minimum pressure difference of 0.7 bar is required for perfect function.

A distinction is made between two different cases for the valve design:•If the pressure difference required is less than 1 bar, the flow speed should be

between 0.2 and 2.5 m/s (case A).•If the pressure difference required is greater than 1 bar, the flow speed should

be between 0.4 and 5 m/s (case B).The following values then apply for calculation of the valve size:

Using the nominal size selected as a basis, it can now be checked whether the given data can be covered with the valve without getting into the cavitation area:

oVERViEW oF THE VARiAnTs

Case Dn 50 65 80 100 125 150 200A Vmin = 0,2 m/s Qmin in l/s 0,4 0,7 1,0 1,6 2,5 3,5 6,3

Qmin in m3/h 1,5 2,5 3,6 5,8 9,0 12,6 22,7Vmax = 2,5 m/s Qmax in l/s 4,9 8,3 13,0 20,0 31,0 44,0 79,0

Qmax in m3/h 17,6 29,9 46,8 72,0 111,6 158,4 284,4B Vmin = 0,4 m/s Qmin in l/s 0,8 1,4 2,0 3,2 5,0 7,0 13,0

Qmin in m3/h 3,0 5,0 7,2 11,6 18,0 25,2 46,8Vmax = 5,0 m/s Qmax in l/s 9,8 17,0 25,0 39,0 61,0 88,0 157,0

Qmax in m3/h 35,3 61,2 90,0 140,4 219,6 316,8 565,2

Functional principle of a pressure reducing valve

Testing the valve’s cavitation behaviour:• Field 1: Normal function without cavitation• Field 2: The differential pressure is too high,

cavitation occurs. If appropriate, two valves can be arranged behind each other.

• Field 3: Outside the permissible area of application

• Field 4: Physically impossible, since the up-stream pressure can never be smaller than the downstream pressure.

Example• There is an upstream pressure of 12 bar

which is to be reduced to a downstream pressure of 6 bar. With the pressure difference of 6 bar, case distinction B is applicable.

• A maximum flow of 65 l / s and minimum of 8 l / s must be managed, in which case a nominal size DN 150 is selected in case B.

• A check based on the diagram confirms that the working point is in area 1 and thus no cavitation will occur.Downstream pressure (bar)

Upst

ream

pre

ssur

e (b

ar)

1

4

3

2


Application scenarios for the ERHARD DHV4 pressure sustaining valve

The ERHARD DVP4 pressure reducing valve has favourable KVS and Zeta values. The KVS value specifies how much water (m3/h) flows through a fully opened valve at a temperature of 5 to 30 °C and a pressure loss of 1 bar. The Zeta value (100 %) is the pressure loss coefficient of the valve in the fully open position.

Dn 50 65 80 100 125 150 200KVS (m3/h) 44 75 103 174 253 358 669Zeta 5,6 6,2 6,0 5,2 6,1 5,0 5,0


Pressure rating Pn

Hydrostatic test pressure in bar

Max. allow. gauge working pressure in bar at +60 °C

50 - 600 16 1,0 - 15,0 16,050 - 600 25 1,0 - 20,0 25,0

There are numerous options available to supplement the ERHARD DVP4 pres-sure reducing valve, e.g. a second pilot valve, solenoids or certain multiple func-tions. One particularly interesting option is the sustaining of upstream pressure, which closes the valve completely when pressure falls below a certain setpoint upstream pressure.

ERHARD DHV4 Pressure sustaining ValveThe task of a pressure sustaining valve is to avoid increased pressures in pipe-lines. For one thing, it opens when a set pressure value is exceeded, thus act-ing as a pressure relief valve and protecting the pipeline from excessively high pressure (diagram A). In addition, it can be used when the upstream pressure is to be kept above a certain limit value, independently of the consumption on the downstream pressure side (diagram B).

A B


ERHARD sVP4 Float ValveThe task of float valves is to maintain a certain water level. If the water level in the tank increases, the float slides upwards to the upper stop. The buoyancy of the float lifts the cable with the weight, the counterweight switches the 3/2 directional valve so that the upstream line is connected with the control line. The upstream pressure closes the main valve. When the float slides down-wards, the process is reversed, the valve remains closed during draw-off from the tank. The main valve only opens once the float has reached the lower stop. The ERHARD SVP4 float valve thus operates in an adjustable water level height range between 50 and 4000 mm as an OPEN-CLOSE valve which is insensi-tive to cavitation. Closing speed can be set, enabling operation with little water hammer.

Sizing is in accordance with the recommended flow quantity.

Additional functions such as flow limitation and sustaining the upstream pres-sure as well as flow speeds of 4 m/s in exceptional cases are possible.

Area of application: Water (max. 70 °C)

size Dn Pressure rating Pn200 10

50 - 200 16250 - 600 on request

Installation options for the ERHARD SVP4 float valve

DN 50 65 80 100 125 150 200l/s 5,0 8,5 12,5 19,5 31,0 44,0 78,5m3/h 18 30 45 70 111 158 283

Feeding from “above”At the outlet of the valve we recommend installing a 90° fitting, the outlet of which ends above the water surface.

Feeding from “below” Feeding from “below”Float control outside the tank


Application scenario of the ERHARD NRV4 level regulation valve

ERHARD nRV4 level Regulation ValveThe ERHARD NRV4 level regulation valve does not use a float to measure the water level, rather this is measured directly by the water pressure in the pilot valve.

If the water level and thus the hydrostatic pressure falls, the valve opens wide enough for feed flow and discharge flow to be balanced. This means the ERHARD NRV4 level regulation valve is not an OPEN-CLOSE valve, but controls the required water quantity flexibly. When a minimum water level is reached, the valve opens completely to achieve fast refilling.


Dimensions and weights of the ERHARD control valves with process-medium and pre-control

Dn l D Pn10/16

D Pn 25 h1 h2

Pn 16h2

Pn 25 e1 e2 Weight in kg

ERHARD DVP4 Pressure Reducing Valve

50 230 165 165 225 85 85 195 135 1765 290 185 185 245 95 95 155 155 2380 310 200 200 265 105 105 165 156 28

100 350 220 235 290 115 115 180 170 36125 400 250 270 385 130 130 190 170 49150 480 285 300 430 145 145 205 185 72200 600 340 360 730 175 175 215 215 116

ERHARD DHV4 Pressure sustaining Valve

50 230 165 165 395 85 85 264 142 1965 290 185 185 419 95 95 235 113 23,580 310 200 200 434 102 102 241 119 27

100 350 220 235 414 112 120 254 132 39125 400 250 270 456 127 137 266 144 47150 480 285 300 492 145 152 159 281 71200 600 340 360 472 182 182 180 180 121

ERHARD sVP4 Float Valve

50 230 165 165 237 85 85 277 142 2465 290 185 185 265 95 95 248 113 28,580 310 200 200 276 102 102 254 119 32,5

100 350 220 235 301 112 120 267 132 44125 400 250 270 395 127 137 279 144 52150 480 285 300 442 145 152 294 159 77200 600 340 360 566 182 182 252 218 127

ERHARD nRV4 level Regulation Valve

50 230 165 – 238 85 – 277 142 14,265 290 185 – 257 95 – 248 113 18,780 310 200 – 277 102 – 254 119 22,6

100 350 220 – 302 120 – 267 132 35,1125 400 250 – 396 137 – 279 144 42,7150 480 285 – 443 152 – 294 159 67,9200 600 340 – 567 182 – 252 218 116,8

L

D


20

ERHARD sV FloAT VAlVEThe tried-and-trusted control valve for level regulationThe ERHARD SV float valve is ideal for reliable level control in drinking water supply systems. The high-quality cast iron body has internal fittings made of stainless steel. The float is also made of stainless steel and is connected with the valve via a double float guide and a pressure-balanced piston. The ERHARD SV float valve is available both with at straight pattern and with an angle pattern body with outlet muff or flange.

All variants are excellent for stable and economic level control. brief specifications for materials and equipment•body: Spheroidal graphite cast iron EN-JS 1050•internal fittings and float: Stainless steel •Corrosion protection: Internal and external fusion bonded epoxy (FBE) coating

Area of application: Water (outlet without pressure)

size Dn

Pressure rating Pn

Hydrostatic test pressure (bar) Max. allow. gauge working pressure in bar at+60 °Cbody seat

50 - 150 10 17,0 11,0 10,0

Dimensions and weights

Dn l H1 H2 H3 min

H3 max D e d h Hub Kvs Wt.

straight pattern design

50 230 371 460 25 1040 165 650 300 300 235 30 3265 290 383 470 33 1030 185 700 300 300 240 48 4180 310 398 540 40 960 200 750 300 300 320 70 48

100 350 399 520 40 980 220 800 400 350 300 112 65125 400 424 560 63 940 250 900 400 350 320 161 86150 480 458 600 75 900 285 1000 400 350 350 223 118

Angle pattern

50 150 350 430 200 1070 165 650 300 300 235 25 2865 165 362 450 215 1050 185 700 300 300 240 49 3680 180 375 520 230 980 200 750 300 300 320 85 43

100 200 374 490 250 1010 220 800 400 350 300 137 57125 225 394 530 275 970 250 900 400 350 320 180 76150 250 418 560 300 940 285 1000 400 350 350 258 100


PREssURE MAnAgEMEnT AnD inTElligEnT ConTRolThe task of water supply systems is to keep households and businesses sup-plied with water at a certain minimum pressure at all times. This also includes the constant supply to critical points such as high buildings or buildings on hills and mountains. The system is thus designed according to the maximum values required for these special points. This means, however, that for the rest of the time such as at night or in months where consumption is low or even zero, the system is over-dimensioned and works with higher pressures than would actu-ally be necessary to supply consumers.

Risk of leaksThis high pressure leads to problems, however, because the higher the pres-sure, the greater the risk of leaks, which also result in even greater water loss at higher pressure. In pipes made of rigid materials, the leakage amount increases in line with the square root of the pressure, so that doubling the pres-sure increases the leakage amount by 41 %, for example. The situation is differ-ent where pipes are made of PVC or fibre cement, where even greater damage is done due to the pressure, and the amount increases by up to a factor of eight when the pressure is doubled.

Concept and advantages of pressure managementThe objective, then, is to reduce pressure as far as possible so that the leakage risk is reduced, yet at the same time guaranteeing water supplies at minimum pressure in all areas of the network. This is the task of pressure management, which offers numerous advantages:•The overall consumption volumes are lower thanks to reduced leak rates and

lower leakage amounts on the one hand, and through the reduced flow at the consumer’s due to reduced pressure on the other.

•Less repair work and an extended service life for pipes and fittings reduces service and maintenance costs.

•At the same time, customer benefits are increased as less complaints are received about leaks, and there is less strain on fittings and domestic appli-ances at the consumer’s.

A: pressure course A (daytime)

At critical point

At critical point

Just upstream of PRV

Just upstream of PRV

Just downstream of PRV

Just downstream of PRV

Pressure in m Pressure in m

A: pressure course b (nighttime)

60 60

20

55

XX XX

100 120


implementation in practiceVarious methods of different complexities are used to put this concept into prac-tice, all of which can be realised using ERHARD control valves. •In the most straightforward case, a pressure reducing valve is used to set

the pressure to a fixed value which is sufficient to guarantee the minimum pressure at the critical point at all times (diagram A). No control is required. The pressure reducing valves ERHARD DVF or ERHARD DVP4 could be used here. This method cannot adapt the pressure to fluctuations in the course of daily and annual usage, but it only involves minimum installation and servicing effort.

•In contrast, this adaptation is at the heart of the second method, time-con-trolled modulation (diagram B). Here, the pressure reducing valve is fitted with a timer which adapts the pressure depending on the time and / or season, so that a smoothed pressure curve can be established. A timing device is available both for the ERHARD REV control valve and for the ERHARD DVP4 pressure reducing valve. Even if this method estimates the draw-off curve on the basis of empirical values and then adapts the pressure accordingly, the actual consumption is not measured.

•This is done with the third method, flow-controlled modulation. A flow meter is installed upstream from the pressure reducing valve (diagram C). On the basis of this data, the pressure reducing valve is controlled depending on con-sumption. ERHARD REV control valves and ERHARD DVP4 pressure reducing valves can be used for this application, too.

•Finally, the closed measuring loop method carries out measurement at one or several critical points. Here, pressure is measured directly at the draw-off point and the measured value is then transmitted to the pressure reducing valve combined with the flow meter either by data cable or using radio tech-nology, in order to guarantee immediate implementation in the control of the pressure reducing valve.

Time control or motorised pilot drives are only some of the options for ERHARD control valves within the context of profes-sional pressure management.

A: Fixed downstream pressure b: Time-controlled modulation C: Flow-controlled modulation

Day 1

Pres

sure

TimeDay 2 Day 3

1 ERHARD needle valve and control valve2 Electronic controller*3 Pressure gauge with teletransmitter4 Flow meter5 Float switch6 PumpW Set pointY Controller output signalX Controller input signalYR Signal feedback

Pressure control: constant downstream pressure (P2)

Flow control: constant flow rate

Rserervoir feeding valve

Pressure control: constant upstream pressure (P1)

by-pass valve: for filling mains with the main valve in closes position

Pump-discharge valve: minimizing water hammer on closing a long delivery line

1P1 P1P2 P2

1

1

1

1

1

2

W

X X

X

Y Y

Y

Q

YR YR

YR

W

W

2

2

3 3

4

5

6

MAX

IDM

MIN

intelligent controlAlongside pure pressure management, there are numerous other control tasks to be dealt with in pipeline networks and systems. These include level control in tanks, for example, the control of defined flow volumes or the reduction of water hammer in pump systems (see diagram above).

ERHARD offers numerous options both for the ERHARD REV control valve and for the ERHARD control valves with pilot and process-medium control to guarantee tailor-made adaptation to the respective job on hand. In addition to the standard products (pages 16 to 20), many other models can be configured thanks to additional pilot variants.

One particularly interesting option is the integration of control technology directly in the actuator, as can be done with AUMA actuators for the ERHARD REV control valve, for example.

AUMA actuator with integrated PID Controller can be perfectly combined with ERHARD control valves.


RECoMMEnDATions FoR insTAllATionControl valves must always be seen as part of an overall installation within the pipeline and be combined with suitable fittings to achieve optimum functionality:•The control valve is installed horizontally in the pipeline.•On the upstream pressure side, a shut-off valve (e.g. ERHARD Multamed Pre-

mium gate valve, ERHARD ROCO Premium butterfly valve or ERHARD ECLI butterfly valve) and a dirt trap with a maximum mesh size of 2 mm must be installed first.

•On the downstream pressure side, a dismantling joint, a safety valve if appro-priate and then another shut-off valve are used.

•Drainage must be planned in the building.•With a downstream pressure line with downward gradient, an air valve (e.g.

ERHARD TWIN-AIR air valve) is also recommended on the downstream pres-sure side, with an upward gradient or horizontal upstream pressure line on the upstream pressure side accordingly.


It was 1871 when the brass caster Johannes Erhard started his business in the small Swabian town of Heidenheim an der Brenz. Since this time, with our valves, we at ERHARD have been helping to ensure that water is available wher-ever it is needed: in private households, in public facilities, in agriculture or in industrial plant.

Proverbial Swabian inventiveness, the most recent technical findings and expe-rience acquired over 140 years ensure that, with innovative solutions and our wide range of products, we can provide suitable systems for every task. Modern machinery, state of the art and environmentally friendly production methods and high-quality materials enable ERHARD to supply technically advanced, fully developed products with worldwide reputation.

But merely delivering a product is not enough, especially for complex techni-cal installations. And so at ERHARD, highly qualified teams are available in our head office in Heidenheim and in representations in more than 50 countries to give you advice and support in all the life cycle phases.

Planning and design:•Individual advice•Development of optimum solutions in dialogue•In-house laboratory for product tests and trials

installation and commissioning•On-site assembly and installation•Training and instruction•Maintenance and repair

inspections and servicing•Fast spare part supply•Repairs on site or in our Heidenheim factory – including third party makes

ExPERTisE THRoUgH TRADiTion


Alongside control valves, the wide ERHARD range also includes numerous other products for pipelines.

ERHARD Multamed Premium gate Valve [1]As gate valves of the latest generation, ERHARD Multamed Premium gate valves offer many advantages such as a concealed stem bearing and stem bearing seal with O-rings that can be replaced under full operating pressure if required. An integrated end stop of the stem thread guarantees increased safety, and the innovative dirt cap with integrated sealing lips provides reliable sealing against dust and humidity. The shut-off wedge made of high-grade cast iron with an all-round elastomer sheathing guarantees soft sealing and absolute airtightness, a guide profile with integrated sliding blocks for easier actuation.

ERHARD RoCo Premium butterfly Valve [2]The soft-sealed butterfly valve with double eccentricity support and optimised flow profile, which has proved its value thousands of times over, has been improved even further. Perfect solutions ensure outstanding product properties with respect to operating safety, durability and cost effectiveness. The innova-tive polygon plug connection between the shaft and the hub ensures perfect traction. The innovative design also permits complete encapsulation of the shaft-hub connection, so there is no longer any contact between the shaft and the medium. Sealing consistently and logically occurs at coated parts of the component, a decisive plus for protection against corrosion and durability. The slider crank mechanism is optimally matched to the characteristic of the valve, guaranteeing safe actuation.

ERHARD TWin-AiR Air Valve [3]Thanks to its large cross-section and very high venting speeds, this air valve is perfect for use in larger pipelines and guarantees safe and automatic venting of the pipe during filling, operational air release in service and emptying. The design is compact and space-saving despite the high capacity.

ERHARD PAs20 Dismantling Joint [4]Equipped with three sturdy flange rings, the ERHARD PAS20 is the perfect solu-tion for all standard applications. It is easy to install and remove thanks to the length compensation V =+/- 20 mm or +/- 25 mm (depending on the nominal size) and thus offers perfect support during the installation and removal of fittings. The ERHARD PAS20 has connection flanges with the same dimensions and to both sides, and is lockable. 100 % tension with sturdy, continuous threaded rods guarantees the required safety.

ERHARD – FoR EVERy AREA oF APPliCATion

1

2

3

4

TALIS is always the number one choice whenever water transport or control is required. TALIS has the best solution for water and energy management, as well as for industry and municipal applications. With a varied range of products we offer comprehensive solutions for the entire water cycle. From hydrants to butterfly valves. From the knife-gate valves to the needle valves. Our experience, innova-tive technology, global expertise and individual consultation process form the basis for developing sustainable solutions for the efficient handling of the vital resource “water”.

Note: Specifications may be changed without notification at any time.Copyright: No copying without express written permission of ERHARDERHARD is a Registered Trademark. 46035 EN (04/15)

www.talis-group.com

ERHARD gmbH & Co. KgPostfach 1280D-89502 HeidenheimMeeboldstrasse 22D-89522 HeidenheimPHonE +49 7321 320-0FAx +49 7321 320-491E-MAil [email protected] www.erhard.de

erhard control valves · for this purpose, control valves are operated in intermediate positions....

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