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Proceedings of the 2002 American Society for Engineering Education Annual Conference & Exposition

Copyright 2002, American Society for Engineering Education

Session

THE MEASUREMENT LOCAL LOSSES AND K FACTOR OFVALVES AND FITTINGS BY COMPUTER

Riza GRBZAnkara University

Cankiri College Of Arts And TechnologyCankiri-Trkiye

E-mail: [email protected]

Abstract

The purpose of this experiment is to measure flow rate, friction factor, velocity of fluid and the K

factor of some valves and fittings such as tee, elbow, Y Junction, gate and globe valves.

It is used computer, pressure differential transmitter, venturi and orifice meter to measure flow rate,

pressure drops on flow rate measurement devices and pressure drops of some valves and fittings to

be measured K factors. It is also measured temperature of fluid.

A computer program is written to calculate Reynold number of fluid, friction factor of pipe, velocity,

local losses of fluid, flow rate and K factor of valves and fittings, required data are received from

measured quantities. Conclusion of experiments are printed as shown next pages of article.

Volumetric flow rate limitations 0-60 (Lpm), pressure drop is 0-100 kPa.

Key words:K factor, fittings, valves, flow rate measurement, local losses.

Introduction

When fluid flows throughout a pipe or conduit, it counters resistance to flow. In straight piping, this

resistance is caused by surface roughness.

In addition to friction losses, there are losses due to turning gate valve, globe valve, flow control

valve, sudden enlargement, 45? or 90? junctions etc. Finally, it took place pressure drop in this

sections of fluid systems local losses. It must be taken care of system design.

All losses can be determined for each of various elements in the system and added together to get

the total system loss. K factor of some elements can be determined using empirical formulas that

have been developed by experimentation.

This permits the calculation of energy losses for any system compenents. Bernoullis equation and

the continuity equation can be used to perform a complete analysis of a fluid power system. This

includes calculating the pressure drops, flow rates and horsepower losses for all components of fluidpower system.


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There are two basic types of flow in pipes, depending on the nature of different factors mentioned

above that affect the flow. The first type is laminar flow, which is characterized by the fluid flowing in

smooth layers of laminae. This type of fluid motion is called streamline flow because all particles of

fluid are moving in parallel paths.

If the velocity of flow reaches a high enough value, the flow ceases to be laminar and becomesturbulent. Movement of a particular becomes random and fluctuates up and down in a direction

perpendicular as well as parallel to the mean flow direction in turbulent flow. Reynold numbers (Re)

is very important to know whether the flow puttern inside a pipe is laminar or turbulent[1].

If Re is less than 2000 the flow is laminar, if Re is greater than 4000, the flow is turbulent. Reynold

numbers between 2000 and 4000 cover a critical zone between laminar and turbulent flow[2].

There are well-established methods for determining friction losses which can be found in numerous

textbooks and engineering handbooks (Two frequently cited references are: Cameron Hydraulic

Data, Ingersall-Rand Co., N.Y., 1970, and Flow of Fluids Through Valves, Fittings, and Pipe,Technical Paper No: 410, crane co., N.Y., 1981)[8].

Additionally, manufacturer produced data sheets and engineering handbooks frequently contain the

design information to determine line losses.

Friction losses are a function of velocity (flow rate), there is unique pressure value for each flow rate

value. Therefore friction losses should be calculated experimentally for the minimum and maximum

flow rates.

Manufacturers of the pipe, valves, fittings, elbow, X.Y.T junction etc. are determined by

computerized friction losses apparatus and are prepared as table in their catalogue or their internet

site.

System Design of Local Losses and K Factor Measurement and Calculation Method

The calculations of K factor of some valves, fittings parts by computer needs pressure transmitter,

Analog-Digital cards, fluid flow rate or velocity of flow device such as venturi or orifice matter,

computer and program to be evaluated the data. For calculating of some data such as Reynold

numbers, friction factor, velocity, specific values should be given for parameters such as pipe

diameters, pipe lengths, fluid specific gravity, dimension of flow rate measurement devices: Analog-digital cards should be suitable for measured physical quantity and maximum-minimum values in

system[3,4].

In order to perform to enormous number of calculations required to optimize complete fluid friction

measurement systems in a reasonable period of time, it becomes necessary to utilize computers. The

value of any numbers parameters can be changed and the effect on overall system performance.

Thus, the use of computers permits to analyze the some parameters very quick and sensitive and all

data can be stored and utilized for measurement, requested data can be got as a table or graphic.


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Figure 1: Block Diagram of Computerized Fluid Friction Apparatus

Fluid Friction Apparatus and Specifications

Fluid friction apparatus is designed to allow the detailed study of fluid friction head losses which

occur when an incompressible fluid flows through pipes bends, valves and pipe flow metering

devices. Pressure differences transmitters (2) Thermocouple (J Model) transmitter and Analog-

Digital Cards were added to system to measure the some quantities (flow rate, velocity of fluid,

Reynolds number, friction factor, losses etc.) [3,5,6].

Figure 2: Schematic diagram of Fluid Friction Apparatus

Fluid

Friction

Apparatus

Measurement

Devices

? Venturi

? Orifice meter

Transmitter

? Pressure Diff.

? Temperature

? Printer

? Hard-Disk

? Floppy Disk

? Computer

? Program

Analog

Digital

Cards


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Index Sheet for Fluid Friction Apparatus

1, 2, 3, 4, (Pipes (7,5, 16, 18 mm)

2. Suddent contraction

3. Sudden Enlargement

4. Ball Valve

5. 45?Elbow

6. 45?Y Junction

7. Gate Valve

8. Globe Valve

9. In-line Strainer

Input Data (SI system)

Fluid Type = Water

Density (? ) = 999 kg/m3 (water)

Specific gravity (g) = 9,81 m/s2 (water)

Viscosity (? ) = 0,001 Pa.s. (water)

Figure 3: Picture of Fluid Friction Apparatus

Data to be calculated

Flow rate (?

V ) = ..... m3/s, L/s.

Velocity (U) = ..... m/s.

Reynolds number (Re) = ................

Friction Factor (f) = ................Local Losses (H) = ......... m.

K factor (KL) = ......... m.

10.90?Elbow

11. 90?Bend

12. 90?T Junction

13. Pitot Static Tube

14. Venturi meter

15. Orifice meter

20,21 U Type manometers (not used)

22-28 Tank unit. (Pump, motor etc.)


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Diameter (inside) (d) = (18,16, 7,5 mm)

Temperature : = (25-28?C)

K (Ventury) : 0,0007 (Cd= 0,98, D= 24 mm , d= 14 mm)

K (Orifice) : 0,0012 (Cd= 0,62, D= 24 mm, d= 20 mm)

n (Turning number): .................. (for gate and globe valves)

Data to be measured.

Pressure Drop (?p), Pa (Venturi and orifice plate) it is used flow rate and Reynold number

Pressure Drop (?p), Pa (input-output of component) it is used K factor and losses.

Equations for Measurement and Calculation

?

V = K h? (Flow rate) Re = ??DU

(Reynold number)

?p = ?g ? h (Pressure Drop) f=25,0Re

079,0 (Friction Factor for Turbulence)

U =4/2D

V

?

?

(Velocity of fluid) HL= KLg2

2U (Local Losses)

Experimental Analysis of Fluid Friction and Discussion

Flow rate of fluid is calculated as below:

?

V = K h? U =4/2D

V?

?

?p = ?g ? h ? h = ?p/ ?g?

V = K g/p ??

K is 0,0007 for used venturi meter.

?p signal is received from pressure differential transmitter between 4-20 mA. and changed as

pressure (Pa).

Flow rate is calculated with computer program as m3/s and converted L/s by multiplying 1/1000.

It is shown an graphics (figure 8-16) of experiments.

Reynold number is dimensionless parameter to determine the type of fluid which is laminar or

turbulence.[1,2,3]

Re =?

?UD

In these experiments Reynold number is above the 4000, therefore fluid type is turbulance flow.

Local losses can be found by using Darcys equation.

HL= KLg2

2U (Local Losses)


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Local losses are generally between 0,5 2 (m) in these experiments (90?bend, 90?elbow, 45?

elbow, 45?Y, 90?T, sudden enlargement, sudden contraction, ball valve, in line strainer, orifice

meter, gate valve and globe vale).

Flow rate is controlled by control valves (V2, V6, V1) to measure K factor at different flow rates.

(see figure 2)

Specifications of Used Transmitters and Analog Digital Cards and Transmitters

Model = Pressure Measurement A/D Card (4) RS 232/RS 485 Converter Card (1)

Output = 15-50-100-500 mV, 4-20 mA. Speed (bps) : 1200, 2400, 4800, 9600

Power = +10 + 30 VDC

Thermocouple (1) Pressure Differential Transmitter (2)

Model = Fe constant (J) Range : 0-60/0-120/0-150 kPa

Range = -200, + 800 ?C Output: 4-20 mA

Figure 5: Analog Digital CardsFigure 4: Pressure Transmitter


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SUMMARY AND CONCLUSION

Determining the K factor of some valves and fittings are used experimental techniques. These parts

are valves and fitting such as tees, elbows and bends.

Experimental tests have shown that local losses are proportional to the square of the velocity of the

fluid and inside diameter of pipe and viscosity of fluid.

It used analog or digital devices to measure pressure differences, and flow rate of fluid.

Analog devices are not proper for sensitive measurement. Therefore it is advised to use digital

pressure differential measurement for computerized measurement.

Computer program helps for calculating quickly and correctly of K factor and other values.

This experimental study has universal structure and can be applied all kind of valves and fittings.

It must be changed pressure difference and other transmitters in according to range of the pressure,

temperature, flow rate etc.

Proportional valves or frequency converter of motor can be used to control flow rate instead of

manual valve control.

It will give more sensitive graphics than applied method.

BIBLIOGRAPHIC INFORMATION

1. Hardy, J.E., Hylton, J.O., Flow Measurement Methods and Applications John Willey and Sons

Publication, ISBN 0-471-24509-7, USA, 1999.

2. Bentley, J., Principles of Measurement Systems Longman Scientific and Technical, ISBN 0-470-21056-7,

USA, 1988.

3. Spitzer, D., Industrial Flow Measurement, Resources for Measurement and Control Series, ISBN 1-55617-

243-5, USA, 1990.

4. Transactions in Measurement and Control, Volume 4, Flow and Level Measurement, OMEGA.

www.omega.com.

5. Grbz, R., The Measurement of Local and Continuous Losses Against the Increasing Flow the byComputer. UMTIK 2000, ISBN Tk 975-429-157-8, Pages 433-451, 13-15 Sept. 2001, METU, Ankara, Turkey.

6. Armfield Armfield, Fluid Friction Apparatus, Issue 7a March 1987 Hampshire, England

www.armfield.co.uk

7. Morison, K., R., JORDAN, P., J., Spreadsheet Documentation for Students and Engineers, The

International Journal of Engineering Education, Volume 16, Number 6, ISSN 0949-149x, page 509-515,

IRELAND, 2000.

8. Ostand, R.P., Richards, P.G. Minimizing Piping Friction Losses in Low-Pressure Regulating Valves.

www.controleng.com/archives/.

BIOGRAPHIC INFORMATION

Figure 7: Venturi meterFigure 6: Orifice meter


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Riza Gurbuz is Vice Principal of Ankara University, Cankiri College of Arts and Technology and is

instructor at mechanical engineering higher technician programme since 1985. For detailed

information, please click below address.

http://cmyo.ankara.edu.tr/ogrgor/ (Select Riza Gurbuz)

Appendixes Experimental Results of Some Fittings and Valves

? Pump button shows the amount of the flow rate on the graphic.

Figure 9: 90Bend (Full open)

Figure 8: 90?Elbow (Full open)

Figure 10: 45?Elbow (Quarter open)


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K factor window (under the pump button) shows average K factor right hand side shows sudden K factor


Figure 11: In-line Strainer (Quarter open)

Figure 12: Orifice Meter (Full open)


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Figure 14: Gate valve (Quarter open)

Figure13: Sudden Contraction (Full open)

Figure 15: Globe valve (Full open)


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Figure 16: Globe valve (Quarter Open)

photo for friction from lab

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