low-pressure testing: pressure regulating valves

Low-Pressure Testing: Pressure Regulating Valves http://www.itrc.org/reports/pdf/valves.pdf ITRC Report No. R 13-003

IRRIGATION

TRAINING &

RESEARCH

CENTER

Low-Pressure Testing Pressure Regulating Valves

August 2013

TTeecchhnniiccaall RReeppoorrtt


Prepared by Dr. Charles Burt Kyle Feist Irrigation Training & Research Center (ITRC) California Polytechnic State University San Luis Obispo, CA 93407-0730 805-756-2379 www.itrc.org

Disclaimer: Reference to any specific process, product or service by manufacturer, trade name, trademark or otherwise does not necessarily imply endorsement or recommendation of use by either California Polytechnic State University, the Irrigation Training & Research Center, or any other party mentioned in this document. No party makes any warranty, express or implied and assumes no legal liability or responsibility for the accuracy or completeness of any apparatus, product, process or data described previously. This report was prepared by ITRC as an account of work done to date.

Irrigation Training & Research Center August 2013

IRRIGATION

TRAINING &

RESEARCH

CENTER


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ACKNOWLEDGEMENTS

ITRC would like to acknowledge the following valve manufacturers for cooperation during the testing:

Eurodrip USA Jain Irrigation John Deere Water Technologies Nelson Irrigation Netafim


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EXECUTIVE SUMMARY

The Irrigation Training & Research Center (ITRC) at California Polytechnic State University (Cal Poly) San Luis Obispo tested performance characteristics of pressure regulating valves from a variety of manufacturers. The purpose of the testing was to evaluate the ability of different models of valves to regulate the pressure in a low-pressure system. The testing concentrated on three specific valve performance characteristics: Minimal variance from the target downstream pressure caused by changes in flow rate or

inlet pressure Minimal hysteresis in outlet pressures Minimal pressure loss (at low inlet pressures) across the valve The testing results indicated the following key points: Pressure regulating valves with 2-way pilots are not suited for truly low pressure systems

due to an inherently higher pressure differential. In other words, if the valves with 2-way pilots are adjusted to regulate an outlet pressure of 13 psi, the majority of valves tested required an inlet pressure of 20 psi to function.

All of the comparable valves with 3-way pilots were affected by the following performance characteristics: o Regulated outlet pressure consistency. Within a specific operating range, the majority

of valves with 3-way pilots have the ability to maintain an outlet pressure of +/- 1.5 psi. Only one valve was able to maintain an outlet pressure within +/-0.5 psi.

o Hysteresis. All of the valves with 3-way pilots exhibited measureable differences in regulated outlet pressures between ON and OFF cycles. Some valves exhibited as much as a 2 psi difference in regulated outlet pressures due to hysteresis.

Many of the valves received by ITRC had incorrect diaphragms or pilot springs installed despite extensive specification of performance requirements and were thus not suited for this research application. It is therefore critical that end users supply specific performance requirements to irrigation dealers and verify the configuration before installation.

ITRC staff followed suggestions from industry professionals to verify that the following potential issues did not adversely affect the test results: o The addition of an air vent directly upstream of the test valve. It was suggested that

the lack of an air vent upstream of the test valve may allow the accumulation of air within the pilot and the chamber above the valve diaphragm. Multiple performance tests were conducted with similar results to those without the air vent. Although ITRC typically recommends the installation of adequate continuous acting air vents along pipeline systems, it had no effect in this instance.

o Insufficient flow rate was present to allow the valve to function as designed. It was believed that some valves required a minimum pressure differential to function properly, and that testing 4 inch valves at 200 gallons per minute did not provide the valves with optimal conditions. Test 1 was conducted with 4 inch valves at flow rates up to 500 gallons per minute without substantial differences in results.


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TABLE OF CONTENTS

Executive Summary .......................................................................................................... ii

Introduction ........................................................................................................................1

Tests ................................................................................................................................1

Valve Assortment ............................................................................................................2

Test Results .........................................................................................................................3

Test 1: Performance with Changing Inlet Pressures ......................................................3

Pressure Regulating Valves with 2-Way Pilots ..................................................................... 4 Pressure Regulating Valves with Incorrect Configurations ................................................... 9 Pressure Regulating Valves with 3-Way Pilots and Correct Design ................................... 12

Test 2: Performance with Changing Inlet Flow Rates .................................................20

Test 3: Minimum Valve Pressure Loss at Various Flow Rates ...................................27

Attachment A. Valve Testing Protocol

Attachment B. Valve Testing Measurement and Uncertainty

Attachment C. 2-Way vs. 3-Way Pilots


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LIST OF FIGURES Figure 1. Example Test 1 graph ........................................................................................................... 3 Figure 2. Test 1 - 4-inch Bermad IR-120 (2-way pilot) ....................................................................... 5 Figure 3. Test 1 - 6-inch Bermad IR-120. 2-way pilot performance .................................................... 5 Figure 4. Test 1 - 3-inch John Deere V2000 (2-way pilot) .................................................................. 6 Figure 5. Test 1 - 3-inch Ooval PH3N00G001 (2-way pilot) ............................................................... 6 Figure 6. Test 1 - 4-inch Ooval PH0400G001 (2-way pilot) ................................................................ 7 Figure 7. Test 1 - 3-inch Ooval ZH3NRDTW02 Blue Spring (2-way pilot) ....................................... 7 Figure 8. Test 1 - 3-inch Ooval ZH3NRDTW02 Red Spring (2-way pilot) ........................................ 8 Figure 9. Test 1 - 4-inch Ooval ZH04RDG001 (2-way pilot) .............................................................. 8 Figure 10. Test 1 - 3-inch Dorot Series 100 with the high pressure diaphragm ................................... 9 Figure 11. Test 1 - 4-inch Dorot Series 100 with high pressure diaphragm ....................................... 10 Figure 12. Test 1 - 4-inch Dorot Series 100 angle valve with high pressure diaphragm ................... 10 Figure 13. Test 1 - 4-inch Ooval ZH04RDG001 with high pressure pilot spring .............................. 11 Figure 14. Test 1 - 3-inch Bermad DN80 (3-way pilot) ..................................................................... 13 Figure 15. Test 1 - 4-inch Bermad IR-120 (3-way pilot) ................................................................... 13 Figure 16. Test 1 - 6-inch Bermad IR-120 (3-way pilot) ................................................................... 14 Figure 17. Test 1 - 6-inch Dorot Series 96 (3-way pilot) ................................................................... 14 Figure 18. Test 1 - 4-inch Dorot Series 96 with metal pilot (3-way pilot) ......................................... 15 Figure 19. Test 1 - 4-inch Dorot Series 96 with high pressure diaphragm (3-way pilot) ................... 15 Figure 20. Test 1 - 4-inch Dorot Series 100 (3-way pilot) ................................................................. 16 Figure 21. Test 1 - 3-inch Dorot Super Gal (3-way pilot) .................................................................. 16 Figure 22. Test 1 - 4-inch Nelson Series 800 (3-way pilot) ............................................................... 17 Figure 23. Test 1 - 4-inch Ooval PH0400G001 (3-way pilot) ............................................................ 17 Figure 24. Test 1 - 4-inch Ooval ZA04RDA001L (3-way pilot) ....................................................... 18 Figure 25. Test 1 - 3-inch Ooval ZH3NRDG001 (3-way pilot) ......................................................... 18 Figure 26. Test 1 - 3-inch Rafael RAF-P (3-way pilot) ...................................................................... 19 Figure 27. Test 1 - 4-inch Rafael RAF-P (3-way pilot) ...................................................................... 19 Figure 28. Test 2 - 3-inch Bermad DN80 ........................................................................................... 20 Figure 29. Test 2 - 4-inch Bermad IR-120 ......................................................................................... 21 Figure 30. Test 2 - 4-inch Dorot Series 96 with low pressure diaphragm and metal pilot ................. 21 Figure 31. Test 2 - 4-inch Dorot Series 96 with high pressure diaphragm and high pressure pilot ... 22 Figure 32. Test 2 - 4-inch Dorot Series 100 ....................................................................................... 22 Figure 33. Test 2 - 3-inch Dorot Super Gal ........................................................................................ 23 Figure 34. Test 2 - 4-inch Nelson Series 800 ..................................................................................... 23 Figure 35. Test 2 - 4-inch Ooval PH0400G001 .................................................................................. 24 Figure 36. Test 2 - 4-inch Ooval ZA04RDA001L ............................................................................. 24 Figure 37. Test 2 - 3-inch Ooval ZH3NRDG001 ............................................................................... 25 Figure 38. Test 2 - 3-inch Rafael RAF-P ........................................................................................... 25 Figure 39. Test 2 - 4-inch Rafael RAF-P ........................................................................................... 26 Figure 40. Minimum valve pressure loss (during operation by pilot control) at 13 psi outlet

pressure at 400 GPM ......................................................................................................... 27 Figure 41. Test 3 - 3-inch Bermad DN80 minimum valve pressure loss values ................................ 29 Figure 42. Test 3 - 4-inch Bermad IR-120 minimum valve pressure loss values............................... 29 Figure 43. Test 3 - 4-inch Dorot Series 96 with metal pilot minimum valve pressure loss values .... 30 Figure 44. Test 3 - 4-inch Dorot Series 96 with plastic pilot minimum valve pressure loss values ... 30 Figure 45. Test 3 - 4-inch Dorot Series 96 with plastic pilot and LP diaphragm minimum valve

pressure loss values ........................................................................................................... 31


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Figure 46. Test 3 - 3-inch Dorot Super Gal minimum valve pressure loss values ............................. 31 Figure 47. Test 3 - 4-inch Nelson Series 800 minimum valve pressure loss values (no

manufacturer data provided) ............................................................................................. 32 Figure 48. Test 3 - 4-inch Ooval PH0400G001 minimum valve pressure loss values ....................... 32 Figure 49. Test 3 - 4-inch Ooval ZA04RDA001L minimum valve pressure loss values ................... 33 Figure 50. Test 3 - 3-inch Ooval ZHNRDG001 minimum valve pressure loss values ...................... 33 Figure 51. Test 3 - 3-inch Rafael RAF-P minimum valve pressure loss values ................................. 34 Figure 52. Test 3 - 4-inch Rafael RAF-P minimum valve pressure loss values ................................. 34

LIST OF TABLES Table 1. List of pressure regulating valve models with 2-way pilot designs used in Test 1 ................ 4 Table 2. List of pressure regulating valve models with incorrect hardware used in Test 1 ................. 9 Table 3. List of appropriate valves used in Test 1 .............................................................................. 12 Table 4. Minimum valve pressure loss (during operation by pilot control) at 13 psi outlet

pressure at 400 GPM ......................................................................................................... 28


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INTRODUCTION

Agricultural irrigation systems, especially drip and microirrigation systems, require constant pressures in order to avoid variations in application rates or pipe breaks due to sudden pressure surges (called “water hammer”). Therefore, in areas where pressure drops or surges are common, pipelines to the irrigation system often require pressure regulating valves at the heads of submains or manifolds. Pressure regulating (PR) valves have a two-fold purpose for agricultural irrigation: they must be able to maintain a pre-set maximum operating pressure in the water line downstream of themselves, and they also serve as isolation valves that can be used to turn an irrigation system or block on and off. Since all pressure regulating valves currently on the market can successfully provide on/off control, the testing conducted by ITRC focused solely on measuring the performance of the valves’ pressure regulation. An “ideal” PR valve should provide sufficient performance in the following areas:

Minimal variance from the target downstream pressure caused by changes in flow rate or inlet pressure. In other words, regardless of increases in the pressure or flow rate upstream of the valve (the valve’s “inlet pressure”), the valve must be able to maintain the maximum pressure in the downstream pipeline (the valve’s “outlet pressure”).

Minimal hysteresis in outlet pressures caused by cyclical (on/off) operation as exhibited between irrigation events. Irrigation systems undergo frequent pressure changes due to blocks or systems turning on and off, backflushing filters, plugged emitters, or other reasons. The pressure regulating valve must be able to respond quickly to changing flow rates and pressures with minimal variations in performance.

Minimal pressure loss (at low inlet pressures) across the valve to enable low pump outlet pressures. All pressure regulating valves require an inlet pressure that is larger than the target outlet pressure. The “pressure loss across the valve” is the difference between the target outlet pressure and the minimum inlet pressure required to produce a constant outlet pressure. In an ideal PR valve, the loss would be minimal, meaning that the valve would not require much excess inlet pressure in order to maintain a low outlet pressure.

Tests

ITRC created three separate tests to measure the performance characteristics of each pressure regulating valve based upon the points above. The three tests were designed to determine the following characteristics: (1) The ability of pressure regulating valves to maintain a constant outlet pressure, with

changes in upstream inlet pressures. (2) The ability of pressure regulating valves to maintain a constant outlet pressure, with

changes in flow rates. (3) The minimum upstream inlet pressure required to regulate an outlet pressure of 13 psi

at various flow rates



Details regarding the test protocols are provided in Attachment A. Similarly, the measurement and calibration techniques as well as measurement hardware utilized during the valve testing is provided in Attachment B. Valve Assortment

The valves tested by ITRC were provided by manufacturers, distributors and irrigation dealers specifically for this project. Product representatives and dealers were given a specific description regarding the constraints of the testing and the expected abilities of the valves to perform at low inlet and outlet pressures. A variety of valve configurations and sizes were received by ITRC for testing that produced a range of results, sometimes directly related to the valve size or configuration. ITRC used all valves received in Test 1. During the test, two issues became apparent:

Pressure regulating valves are commonly controlled by either a 2-way pilot or a 3-way pilot. Due to the design characteristics of the 2-way pilot valves, none of the 2-way pilot valves were able to perform within the requirements of a true low pressure system application, but instead all required a substantial pressure loss across the valve body to enable downstream pressure regulation. Therefore, it was determined that two-way pilot valves are not suited to low-pressure system applications. For a description of the difference between 2-way and 3-way pilot valves, please see Attachment C.

Multiple valves were received by ITRC with incorrect hardware combinations such as pilot springs and diaphragms, which negatively affected the performance of the valves. ITRC was able to identify certain elements that made these valve combinations unsuitable for low-pressure system applications.

As a result of the two discoveries mentioned above, only correctly-equipped 3-way pilot valves were used for Tests 2 and 3.



TEST RESULTS

Test 1: Performance with Changing Inlet Pressures

The intention of the first test was to start testing the valves at an inlet pressure above a low pressure system target level (13 psi), and then slowly decrease the inlet pressure until the inlet pressure reached 10 psi, forcing the valve to fully open in order to attempt to regulate the outlet pressure. Then, the flow was slowly increased until it reached the original test starting pressure. After the initial pilot adjustments, the pilot setting was not adjusted throughout the test. As seen in Figure 2, the graphs provided were intended to show two lines: The blue line represents the valve’s outlet pressure in relation to the inlet pressure as the inlet pressure decreases. The red line represents the outlet pressure as the inlet pressure increases back to the test’s starting pressure. A “good” valve performance would look something like the graph in Figure 2, where the valve is able to maintain the target pressure relatively well until the inlet pressure drops to slightly above to the target outlet pressure, and the valve can no longer regulate. Then, a well-performing valve should be able to repeat the same relationship in reverse, as the pressure increases again (i.e., with minimal hysteresis).

Figure 1. Example Test 1 graph

Inlet Pressure (psi)

Outlet Pressure (psi)

Target Pressure

Test Time as Pressure Decreases

Test Time as Pressure Increases

Test End

Test Start



Pressure Regulating Valves with 2-Way Pilots

ITRC was supplied with PR valves that were plumbed with 2-way pilots. As shown in the following graphs, none of the 2-way pilot valves were able to perform satisfactorily during Test 1, because all of the models required inlet pressures that were significantly higher than the “low-pressure” test scenario of a 13 psi target outlet pressure. Two-way pilot PR valves are much better suited for situations where the inlet pressure is substantially higher than the target outlet pressure. However, since this set of tests was focused on low-inlet pressure applications, testing on these models was halted after the first half of Test 1, and none of the valves with 2-way pilots were included in Tests 2 and 3. Therefore, the graphs for the 2-way pilot designs only show the results of the decreasing-pressure part of Test 1. Table 1 lists the 2-way pilot models and their performance graphs are included in Figure 2 through Figure 9.

Table 1. List of pressure regulating valve models with 2-way pilot designs used in Test 1

Manufacturer

Model

Size (in.)

Pilot Type

Pilot Model

Spring Model

Spring P

Range (psi)

Diaphragm

Type

Bermad IR‐120 4 2‐way PC‐20 K 7 to 45 Standard

Bermad IR‐120 6 2‐way PC‐20 K 7 to 45 Standard

John Deere V2000 3 2‐way/3‐way hybrid T Standard 7 to 44 Standard

Ooval PH3N00G001 3 2‐way P‐21 Blue 7 to 144 Standard

Ooval PH0400G001 4 2‐way P‐21 Red 7 to 220 Standard

Ooval ZH3NRDTWO2 3 2‐way P‐21 Blue 7‐145 Standard

Ooval ZH3NRDTWO2 3 2‐way P‐21 Red 7 to 220 Standard

Ooval ZH04RDG001 4 2‐way P‐21 Red 7 to 220 Standard



Figure 2. Test 1 - 4-inch Bermad IR-120 (2-way pilot)

Figure 3. Test 1 - 6-inch Bermad IR-120. 2-way pilot performance

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

0 4 8 12 16 20 24 28 32 36 40 44 48 52 56 60



Decreasing Inlet Pressure

Bermad4" IR‐120 PC‐20 PilotK Spring ( 7 ‐ 45 psi) Standard Diaphragm

Start Inlet: 31.2 psiStart Outlet: 12.9 psiFlow: 194 GPM

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

0 4 8 12 16 20 24 28 32 36 40 44 48 52 56 60




Bermad6" IR‐120PC‐20 PilotK SpringStandard Diaphragm

Start Inlet: 30.2 psiStartOutlet: 13.0 psiFlow: 505 GPM



Figure 4. Test 1 - 3-inch John Deere V2000 (2-way pilot)

Figure 5. Test 1 - 3-inch Ooval PH3N00G001 (2-way pilot)

0

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2

3

4

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8

9

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13

14

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16

0 4 8 12 16 20 24 28 32 36 40 44 48 52 56 60




John DeereV2000 3"T PilotStandard Spring ( 7 ‐ 44 psi ) Standard Diaphragm


0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

0 4 8 12 16 20 24 28 32 36 40 44 48 52 56 60



Deacreasing Inlet Pressure

Ooval3" PH3N00G001P‐21 PilotBlue Spring ( 7 ‐ 144 psi )Standard Diaphragm

Start Inlet: 57.03 psiStart Outlet: 13 psiFlow: 200 GPM



Figure 6. Test 1 - 4-inch Ooval PH0400G001 (2-way pilot)

Figure 7. Test 1 - 3-inch Ooval ZH3NRDTW02 Blue Spring (2-way pilot)

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9

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13

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16

0 4 8 12 16 20 24 28 32 36 40 44 48 52 56 60




Ooval4" PH0400G001P‐21 PilotRed Spring (7‐220 psi)StandardDiaphragm


0

1

2

3

4

5

6

7

8

9

10

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13

14

15

16

0 4 8 12 16 20 24 28 32 36 40 44 48 52 56 60




Ooval3" ZH3NRDTWO2P‐21 PilotBlue Spring (7‐145 psi)StandardDiaphragm




Figure 8. Test 1 - 3-inch Ooval ZH3NRDTW02 Red Spring (2-way pilot)

Figure 9. Test 1 - 4-inch Ooval ZH04RDG001 (2-way pilot)

0

1

2

3

4

5

6

7

8

9

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12

13

14

15

16

0 4 8 12 16 20 24 28 32 36 40 44 48 52 56 60




Ooval3" ZH3NRDTWO2 P‐21 PilotRed Spring (7 ‐ 220 psi)StandardDiaphragm

Start Inlet: 32 psiStartOutlet: 13 psiFlow: 200 GPM

0

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3

4

5

6

7

8

9

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0 4 8 12 16 20 24 28 32 36 40 44 48 52 56 60

OUtlet Pressure (p

si)



Ooval4" ZH04RDG001P‐21 PilotRed SpringStandard Diaphragm




Pressure Regulating Valves with Incorrect Configurations

Four of the PR valves received showed erratic results during Test 1. Upon further inspection, it was apparent that all four had arrived with the incorrect hardware for the testing configurations: three contained diaphragms for high inlet pressure applications, and one had a high-pressure pilot spring. Therefore, these four valves were not used for Tests 2 and 3. Table 2 lists the low-performing valves used in Test 1, and their performance graphs are shown in Figure 10 through Figure 13.

Table 2. List of pressure regulating valve models with incorrect hardware used in Test 1

Manufacturer

Model

Size (in.)

Pilot Type

Pilot Model

Spring Model

Spring P

Range (psi)

Diaphragm

Type

Hardware

Issue

Dorot Series 100 3 3‐way 29‐100 Yellow 7 to 30 032 (HP) HP Diaphragm



Ooval ZH04RDG001 3 3‐way P‐31 Red 8‐88 Standard HP Pilot Spring

Figure 10. Test 1 - 3-inch Dorot Series 100 with the high pressure diaphragm

10

11

12

13

14

15

16

17

18

10 12 14 16 18 20 22 24 26 28 30

Outlet Pressure (p

si)


Decreasing Pressure

Increasing Pressure

DorotSeries 100 3"29‐100 PilotYellow Spring (7 ‐ 30 psi)032 (HP) Diaphragm

Start Inlet: 25 psiStart Outlet: 13 psiFlow: 200 GPM

Wrong Diaphragm



Figure 11. Test 1 - 4-inch Dorot Series 100 with high pressure diaphragm

Figure 12. Test 1 - 4-inch Dorot Series 100 angle valve with high pressure diaphragm

10

11

12

13

14

15

16

17

18

10 12 14 16 18 20 22 24 26 28 30



Decreasing Pressure

Increasing Pressure



Wrong Diaphragm

10

11

12

13

14

15

16

17

18

10 12 14 16 18 20 22 24 26 28 30

Outlet Pressure (p

si)


Decreasing Pressure

Increasing Pressure

DorotSeries 100 Angle 4"29‐100 PilotYellow Spring (7 ‐ 30 psi)032 (HP) Diaphragm


Wrong Diaphragm



Figure 13. Test 1 - 4-inch Ooval ZH04RDG001 with high pressure pilot spring

10

11

12

13

14

15

16

17

18

10 12 14 16 18 20 22 24 26 28 30



Decreasing Pressure

Increasing Pressure

OovalZH04RDG001 4"P‐31 PilotRed Spring (8‐88 psi)Standard Diaphragm


Wrong Pilot Spring



Pressure Regulating Valves with 3-Way Pilots and Correct Design

Fourteen of the pressure regulating valves provided to ITRC for testing contained 3-way pilots and the appropriate design for the low inlet pressure test scenarios (see Table 3). Two of the valves performed poorly despite having the correct hardware, and were not carried forward to Test 2 and Test 3. Performance graphs for these valves are included in Figure 14 through Figure 27.

Table 3. List of appropriate valves used in Test 1

*Two valves tested did not perform well during Test 1; therefore, these valves were not tested further

Valve ID

Manufacturer

Distributor

Model

Size

Pilot Type

Pilot Model

Spring Model

Spring P Range

(psi)

Diaphragm

Type

5‐A Bermad Bermad IR‐120 6 3‐way PC‐X K 7 to 45 Standard

4‐A Bermad Bermad IR‐120 4 3‐way PC‐X‐A‐P K 7 to 45 Standard

4‐B Dorot Netafim Series 96 4 3‐way 29‐100 Yellow 7 to 30 095 (HP)

4‐C* Dorot Netafim Series 96 4 3‐way 31‐310 Yellow 7 to 30 095 (HP)

4‐D Dorot Netafim Series 96 4 3‐way 31‐310 Yellow 7 to 30 179 (LP)

4‐E Dorot Netafim 100 4 3‐way 29‐100 Yellow 7 to 30 005 (LP)

4‐F Nelson Nelson 800 4 3‐way Standard Standard 5 to 50 Standard

4‐G Ooval Eurodrip PH0400G001 4 3‐way P‐31 Blue 5 to 36 Standard

4‐H Ooval Eurodrip ZA04RDA001L 4 3‐way P‐31 Blue 5 to 36 Standard

4‐I Rafael Jain RAF‐P 4 3‐way PC Blue 7 to 22 Standard

3‐A Bermad Bermad DN80 3 3‐way PC‐X‐A‐P K 7 to 45 Standard

3‐B Dorot Netafim Super Gal 3 3‐way 29‐100 Yellow 7 to 30 Standard

3‐C Ooval EuroDrip ZH3NRDG001 3 3‐way P‐31 Blue 5 to 36 Standard

3‐D Rafael Jain RAF‐P 3 3‐way PC Blue 7 to 22 Standard



Figure 14. Test 1 - 3-inch Bermad DN80 (3-way pilot)


10

11

12

13

14

15

16

17

18

10 12 14 16 18 20 22 24 26 28 30



Decreasing Pressure

Increasing Pressure

BermadDN80 3"PC‐X pilotK Spring (7‐45 psi)Standard Diaphragm


10

11

12

13

14

15

16

17

18

10 12 14 16 18 20 22 24 26 28 30

Outlet Pressure (p

si)


Decreasing Pressure

Increasing Pressure

BermadIR‐120 4"PC‐X PilotK Spring (7‐45 psi)Standard Diaphragm





Figure 17. Test 1 - 6-inch Dorot Series 96 (3-way pilot)

10

11

12

13

14

15

16

17

18

10 12 14 16 18 20 22 24 26 28 30



Decreasing Pressure

Increasing Pressure

BermadIR‐120 6"PC‐X PilotK Spring (7‐45 psi)Standard Diaphragm


10

11

12

13

14

15

16

17

18

10 12 14 16 18 20 22 24 26 28 30



Decreasing Pressure

Increasing Pressure

DorotSeries 96 4"31‐310 PilotYellow Spring (7‐30 psi)095 (HP) Diaphragm

Start Input: 25.01 psiStart Output: 13.02 psiFlow: 202 GPM



Figure 18. Test 1 - 4-inch Dorot Series 96 with metal pilot (3-way pilot)

Figure 19. Test 1 - 4-inch Dorot Series 96 with high pressure diaphragm (3-way pilot)

10

11

12

13

14

15

16

17

18

10 12 14 16 18 20 22 24 26 28 30



Decreasing Pressure

Increasing Pressure

DorotSeries 96 4"31‐310 PilotYellow Spring (7‐30 psi)179 (LP) Diaphragm


10

11

12

13

14

15

16

17

18

10 12 14 16 18 20 22 24 26 28 30

Outlet Pressure (p

si)


Decreasing Pressure

Increasing Pressure





Figure 20. Test 1 - 4-inch Dorot Series 100 (3-way pilot)

Figure 21. Test 1 - 3-inch Dorot Super Gal (3-way pilot)

10

11

12

13

14

15

16

17

18

10 12 14 16 18 20 22 24 26 28 30



Decreasing Pressure

Increasing Pressure

DorotSeries 100 4"29‐100 PilotYellow Spring (7 to 30 psi)005 (LP) Diaphragm


10

11

12

13

14

15

16

17

18

10 12 14 16 18 20 22 24 26 28 30

Outlet Pressure (p

si)


Decreasing Pressure

Increasing Pressure

DorotSuper Gal 3"29‐100 PilotYellow SpringStandard Diaphragm

Start Inlet: 25 psiStartOutlet: 13 psiFlow: 200 GPM



Figure 22. Test 1 - 4-inch Nelson Series 800 (3-way pilot)

Figure 23. Test 1 - 4-inch Ooval PH0400G001 (3-way pilot)

10

11

12

13

14

15

16

17

18

10 12 14 16 18 20 22 24 26 28 30

Outlet Pressure (p

si)


Decreasing Pressure

Increasing Pressure

NelsonSeries 800 4"Standard PilotC1 Spring ( 10 ‐ 50 psi )Standard Diaphragm

Start Input: 30.0 psiStart Output: 13.0 psiFlow: 512 GPM

10

11

12

13

14

15

16

17

18

10 12 14 16 18 20 22 24 26 28 30



Decreasing Pressure

Increasing Pressure

OovalPH0400G001 4"P‐31 PilotBlue Spring (5‐36 psi)Standard Diaphragm




Figure 24. Test 1 - 4-inch Ooval ZA04RDA001L (3-way pilot)

Figure 25. Test 1 - 3-inch Ooval ZH3NRDG001 (3-way pilot)

10

11

12

13

14

15

16

17

18

10 12 14 16 18 20 22 24 26 28 30



Decreasing Pressure

Increasing Pressure

OovalZA04RDA001L 4"P‐31 PilotBlue springStandard Diaphragm

Start Inlet: 25 psiStart Outlet: 13.03 psiFlow: 200 GPM

10

11

12

13

14

15

16

17

18

10 12 14 16 18 20 22 24 26 28 30



Decreasing Pressure

Increasing Pressure

OovalZH3NRDG001 3"P‐31 PilotBlue SpringStandard Diaphragm




Figure 26. Test 1 - 3-inch Rafael RAF-P (3-way pilot)

Figure 27. Test 1 - 4-inch Rafael RAF-P (3-way pilot)

10

11

12

13

14

15

16

17

18

10 12 14 16 18 20 22 24 26 28 30



Decreasing Pressure

Increasing Pressure

Rafael3" RAF‐PPC pilotBlue Spring (7‐22 psi)Standard Diaphragm


10

11

12

13

14

15

16

17

18

10 12 14 16 18 20 22 24 26 28 30



Decreasing Pressure

Increasing Pressure

Rafael4" RAF‐PPC PilotBlue Spring (7‐22 psi)Standard Diaphragm




Test 2: Performance with Changing Inlet Flow Rates

The intention of the second test was to configure the valve inlet and discharge pressures at conditions replicating a low pressure system at a low flow rate of 100 GPM. The test proceeded by substantially increasing the flow rate to 500 GPM while maintaining the initial inlet pressure and monitoring the subsequent outlet pressure. Due to large pressure losses with some valves, a flow rate of 500 GPM was not reached. After the initial pilot adjustment, the pilot setting was not changed throughout the test. As seen in Figure 28, the graphs provided were intended to show two lines: The blue line represents the valve’s outlet pressure in relation to the flow rate through the valve. The red line represents the inlet pressure in relation to the flow rate, which remained constant throughout the test. An “ideal” valve performance would look something like the graph in Figure 34, where the valve is able to maintain the target pressure relatively well throughout a large range of flow rates.

Figure 28. Test 2 - 3-inch Bermad DN80

0

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20

22

0 100 200 300 400 500 600

Pressure (psi)

Flow rate (GPM)

Outlet Pressure

Inlet Pressure

BermadDN80 3"PC‐X pilotK Spring (7‐45 psi)Standard Diaphragm

Start Inlet: 20 psiStart Outlet: 13 psiFlow: 100 GPM



Figure 29. Test 2 - 4-inch Bermad IR-120

Figure 30. Test 2 - 4-inch Dorot Series 96 with low pressure diaphragm and metal pilot

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20

22

0 100 200 300 400 500 600

Pressure (psi)

Flow rate (GPM)

Outlet Pressure

Inlet Pressure

BermadIR‐120 4"

PC‐X PilotK Spring (7‐45 psi)Standard Diaphragm

Start Inlet: 20.4 psiStart Outlet: 13 psiFlow: 104 GPM

0

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20

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0 100 200 300 400 500 600

Pressure (psi)

Flow rate (GPM)

Outlet Pressure

Inlet Pressure

DorotSeries 96 4"31‐310 PilotYellow Spring (7‐30 psi)179 (LP) Diaphragm




Figure 31. Test 2 - 4-inch Dorot Series 96 with high pressure diaphragm and high pressure

pilot

Figure 32. Test 2 - 4-inch Dorot Series 100

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Pressure (psi)

Flow rate (GPM)

Outlet Pressure

Inlet Pressure


Start Inlet: 20.0 psiStart Outlet: 13.0 psi

Flow: 100 GPM

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Pressure (psi)

Flow rate (GPM)

Outlet Pressure

Inlet Pressure

DorotSeries 100 4"29‐100 PilotYellow Spring (7 to 30 psi)005 (LP) Diaphragm




Figure 33. Test 2 - 3-inch Dorot Super Gal

Figure 34. Test 2 - 4-inch Nelson Series 800

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Pressure (psi)

Flow rate (GPM)

Outlet Pressure

Inlet Pressure

DorotSuper Gal 3"29‐100 PilotYellow Spring ( 7 to 30 psi )Standard Diaphragm


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0 100 200 300 400 500 600

Pressure (p

si)

Flow rate (GPM)

Outlet Pressure

Inlet Pressure

NelsonSeries 800 4"

Standard PilotC1 Spring ( 10 ‐ 50 psi )Standard Diaphragm

Start Input: 20.0 psiStart Output: 13.1 psi

Flow: 106 GPM



Figure 35. Test 2 - 4-inch Ooval PH0400G001

Figure 36. Test 2 - 4-inch Ooval ZA04RDA001L

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Pressure (p

si)

Flow rate (GPM)

Outlet Pressure

Inlet Pressure

OovalPH0400G001 4"P‐31 PilotBlue Spring (5‐36 psi)

Standard Diaphragm


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Pressure (p

si)

Flow rate (GPM)

Outlet Pressure

Inlet Pressure

OovalZA04RDA001L 4"

P‐31 PilotBlue Spring (5‐36 psi)Standard Diaphragm

Start Inlet: 20.0 psi

Start Outlet: 13.0 psiFlow: 100 GPM



Figure 37. Test 2 - 3-inch Ooval ZH3NRDG001

Figure 38. Test 2 - 3-inch Rafael RAF-P

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Pressure (p

si)

Flow rate (GPM)

Outlet Pressure

Inlet Pressure

OovalZH3NRDG001 3"

P‐31 PilotBlue Spring (5‐36 psi)Standard Diaphragm


Flow: 102 GPM

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Pressure (p

si)

Flow rate (GPM)

Outlet Pressure

Inlet Pressure

Rafael3" RAF‐PPC pilotBlue Spring (7‐22 psi)

Standard Diaphragm




Figure 39. Test 2 - 4-inch Rafael RAF-P

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Pressure (p

si)

Flow rate (GPM)

Outlet Pressure

Inlet Pressure

Rafael4" RAF‐PPC PilotBlue Spring (7‐22 psi)

Standard Diaphragm


Flow: 99 GPM



Test 3: Minimum Valve Pressure Loss at Various Flow Rates

Test 3 examined the minimum valve pressure loss at various flow rates. This was determined by subtracting the downstream pressure at each measured flow rate from the minimum upstream pressure that still maintained the target downstream pressure. The results of the ITRC testing were then compared with the values for minimum valve pressure loss listed for each model in the manufacturers’ published specifications, as well as the values provided by the equipment distributor (if available). The overall results are presented graphically in Figure 40 and in table format in Table 4. The test vs. manufacturer value graphs are presented for each model individually in Figure 41 through Figure 52.

Figure 40. Minimum valve pressure loss (during operation by pilot control) at 13 psi outlet

pressure at 400 GPM

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18

3‐A 3‐B 3‐C 3‐D 4‐A 4‐B 4‐D 4‐E 4‐F 4‐G 4‐H 4‐I

Minim

um Valve

Pressure Loss (psi)

Valve ID

ITRC Results

Manufacturer Values

Distributor Values



Table 4. Minimum valve pressure loss (during operation by pilot control) at 13 psi outlet pressure at 400 GPM

Minimum Valve Pressure Loss (During Operation by Pilot Control)

to Outlet 13 PSI @ 400 GPM

Notes Valve ID

Manufacturer

Distributor

Model

Size

Pilot Type

Pilot Model

Spring Model

Spring P Range

(psi)

Diaphragm

Type

ITRC M

easured

Value (psi)

Manufacturer

Stated

Value

(psi)

Distributor

Stated

Value

(psi)

4‐A Bermad Bermad IR‐120 4 3‐way PC‐X‐A‐P K 7 to 45 Standard 3.7 2.9 2.9

4‐B Dorot Netafim Series 96 4 3‐way 29‐100 Yellow 7 to 30 095 (HP) 3.7 3 3

4‐D Dorot Netafim Series 96 4 3‐way 31‐310 Yellow 7 to 30 179 (LP) 5.4 3 3

4‐E Dorot Netafim 100 4 3‐way 29‐100 Yellow 7 to 30 005 (LP) 3.7 2.1 2.6

4‐F Nelson Nelson 800 4 3‐way Standard Standard 5 to 50 Standard 0.9 No pressure loss information available online

4‐G Ooval Eurodrip PH0400G001 4 3‐way P‐31 Blue 5 to 36 Standard 3.2 2.1 2.1

4‐H Ooval Eurodrip ZA04RDA001L 4 3‐way P‐31 Blue 5 to 36 Standard 2.3 1.4 1.4

4‐I Rafael Jain RAF‐P 4 3‐way PC Blue 7 to 22 Standard 9.5 3

No pressure loss information available online from distributor

3‐A Bermad Bermad DN80 3 3‐way PC‐X‐A‐P K 7 to 45 Standard 17.3 10.5 10.5

ITRC value was extrapolated; best estimate for manufacturer stated value

3‐B Dorot Netafim Super Gal 3 3‐way 29‐100 Yellow 7 to 30 Standard 11.3 3.8 6

Best estimate of manufacturer and distributor stated values

3‐C Ooval EuroDrip ZH3NRDG001 3 3‐way P‐31 Blue 5 to 36 Standard 6.9 4.4 4.4 Best estimate of manufacturer stated value

3‐D Rafael Jain RAF‐P 3 3‐way PC Blue 7 to 22 Standard 9.6 3

No pressure loss information available online from distributor



Figure 41. Test 3 - 3-inch Bermad DN80 minimum valve pressure loss values

Figure 42. Test 3 - 4-inch Bermad IR-120 minimum valve pressure loss values

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15

0 100 200 300 400

Minim

um Valve Pressure loss (psi)

Flow Rate (GPM)

ITRC Results

Manufacturer Stated Values

Bermad3" DN80PC‐X pilotK Spring (7‐45 psi)Standard Diaphragm

0

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7

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13

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15

0 100 200 300 400 500 600

Minim

um Valve

Pressure Loss (p

si)

Flow Rate (GPM)

ITRC Results


Bermad4" IR‐120PC‐X PilotK Spring (7‐45 psi)Standard Diaphragm



Figure 43. Test 3 - 4-inch Dorot Series 96 with metal pilot minimum valve pressure loss values

Figure 44. Test 3 - 4-inch Dorot Series 96 with plastic pilot minimum valve pressure loss values

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9

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13

14

15

0 100 200 300 400 500 600

Minim

um Valve Pressure loss (psi)

Flow Rate (GPM)

ITRC Results


DorotSeries 96 4"31‐310 PilotYellowSpring ( 7 ‐ 30 psi )179 (LP) Diaphragm

0

1

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5

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7

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9

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11

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13

14

15

0 100 200 300 400 500 600

Minim

um Valve Pressure Loss (psi)

Flow Rate (GPM)

ITRC Results


DorotSeries 96 4"29‐100 PilotYellow Spring ( 7 ‐ 30 psi )095 (HP) Diaphragm



Figure 45. Test 3 - 4-inch Dorot Series 96 with plastic pilot and LP diaphragm minimum valve

pressure loss values

Figure 46. Test 3 - 3-inch Dorot Super Gal minimum valve pressure loss values

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9

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15

0 100 200 300 400 500 600

Minim


Flow Rate (GPM)

ITRC Results


Dorot4" Series 100 29‐100Yellow Spring (7 to 30 psi)005 (LP) Diaphragm

0

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7

8

9

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11

12

13

14

15

0 100 200 300 400 500

Minim


Flow Rate (GPM)

ITRC Results


Dorot3" Super Gal

29‐100 pilotYellow Spring (7 ‐30

psi)Standard Diaphragm



Figure 47. Test 3 - 4-inch Nelson Series 800 minimum valve pressure loss values (no

manufacturer data provided)

Figure 48. Test 3 - 4-inch Ooval PH0400G001 minimum valve pressure loss values

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7

8

9

10

11

12

13

14

15

0 100 200 300 400 500 600

Minim


Flow Rate (GPM)

ITRC Results

NelsonSeries 800 4"StandardPilotC1 Spring ( 10 ‐ 50 psi )Standard Diapghragm

0

1

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5

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7

8

9

10

11

12

13

14

15

0 100 200 300 400 500 600

Minim


Flow Rate (GPM)

ITRC Results


Ooval4" PH0400G001P‐31 PilotBlue Spring (5 to 36) psi)Standard Diaphragm



Figure 49. Test 3 - 4-inch Ooval ZA04RDA001L minimum valve pressure loss values

Figure 50. Test 3 - 3-inch Ooval ZHNRDG001 minimum valve pressure loss values

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11

12

13

14

15

0 100 200 300 400 500 600

Minim


Flow Rate (GPM)

ITRC Results


Ooval4" ZA04RDA001LP‐31 PilotBlue Spring (7 to 30 psi)Standard Diaphragm

0

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7

8

9

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11

12

13

14

15

0 100 200 300 400 500 600

Minim

um Valve

Pressure Loss (p

si)

Flow Rate (GPM)

ITRC Results


Ooval3" ZH3NRDG001P‐31 PilotBlue Spring (7 to 30 psi)Standard Diaphragm



Figure 51. Test 3 - 3-inch Rafael RAF-P minimum valve pressure loss values

Figure 52. Test 3 - 4-inch Rafael RAF-P minimum valve pressure loss values

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8

9

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12

13

14

15

0 100 200 300 400 500

Minim


Flow Rate (GPM)

ITRC Results

Manufacturer Stated Value

Rafael3" RAF‐PPC PilotBlue Spring (7 to 22 psi)Standard Diaphragm

0

1

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7

8

9

10

11

12

13

14

15

0 100 200 300 400 500

Minim


Flow Rate (GPM)

ITRC Results

Manufacturer Stated Results

Rafael4" RAF‐P

PC PilotBlue Spring (7 to 22 psi)

Standard Diaphragm


Irrigation Training & Research Center

ATTACHMENT A Valve Testing Protocol


Irrigation Training & Research Center P a g e | A-1

Attachment A Valve Testing Protocol

Test 1 Protocol

Figure A1. Test 1 & 2 setup

1. Configure the valves and piping as shown in Figure A1.

a. The u/s gate valve is adjusted to deliver 25 psi. b. The pressure regulating valve is to be adjusted to set the downstream pressure to

13 psi. c. The downstream gate valve is adjusted to set the flow rate to 200 GPM.

2. The u/s gate valve is re-adjusted to 25 psi. NOTE: If the valve has a high inherent friction loss, it may be necessary to increase the inlet pressure to the test valve to 30-35 psi in order to record a minimum of 4-5 data points before the valve has opened to its full extent. 3. The pressure regulating valve, d/s gate valve, and u/s gate valve are all re-adjusted so that

there is 13 psi out of the test valve, 200 GPM, and 25 psi into the test valve. 4. Change the u/s gate valve in increments of 1 psi decreasing. Measure the d/s pressure

from the test valve, and the flow rate. NOTE: The remainder of Test 1, and Tests 2 and 3 may not be completed if the valve exhibits an inability to perform at a satisfactory level with a low downstream pressure. Less than satisfactory performance includes:

the valve cannot maintain a downstream pressure of 13 psi (+/- 1.5 psi) during normal operation and/or

the valve requires an inlet pressure of more than 5 psi over the regulated downstream pressure for normal operation.

5. Once arriving at 13 psi, go back upward at 1 psi at a time, to 25 psi. Measure the d/s

pressure from the test valve, and the flow rate.



Test 2 Protocol 1. Start the test for a change in flow rate. 2. Re-adjust the u/s gate valve so that the pressure into the test valve is 20 psi. 3. Fine tune the test valve and the d/s gate valve so the test valve delivers 13 psi at

100 GPM. 4. Re-adjust the u/s gate valve, the test valve, and the d/s gate valve so there is 20 psi into

the test valve and 13 psi and 100 GPM out. 5. Record the pressure in and out of the test valve, and the flow rate. 6. Re-set the d/s gate valve to a flow of 200 GPM. Re-adjust the pressure into the test valve

to 20 psi. Re-adjust until there is the 200 GPM and 20 psi. **Do not adjust the test valve pilot***

7. Record the d/s pressure. 8. Repeat (6) with flow rates of 300, 400, and 500 GPM.

Test 3 Protocol

Figure A2. Test 3 setup

1. Configure the valves and piping as shown in Figure A2. 2. The selection switch on the pressure regulating valve (“Test Valve”) has been set to

“Open”. 3. Open the pilot valve on the test valve to full open. 4. Adjust the flow control valve so that it is about 1/3 open. 5. Open the 2nd pressure reducer valve so it’s about half open. 6. Open the first pressure reducer valve so that there is about 40 psi just d/s of it. This

does not need to be precise, and can be adjusted any time. The purpose of this valve is to perform initial pressure dissipation so that the 2nd pressure reducer valve is more precise.

7. Using the flow control valve, set the flow rate to about 60 GPM. 8. Adjust the 2nd pressure reducer valve so it is delivering 25 psi. 9. Adjust the pilot of the “test valve” and the flow control valve together so that the flow

is 60 GPM at 13 psi outlet pressure from the “test valve”. 10. Re-adjust the 2nd pressure reducing valve so it is delivering 25 psi. 11. Again, adjust the flow control valve and pilot of the “test valve” so it is delivering

about 60 GPM 12. Record:

a. The pressure d/s of the “test valve” (it should be precisely 13 psi on this first go-around)



b. The pressure u/s of the test valve (it should be 25 psi) c. The flow rate through the valve (it should be precisely 60 GPM), as measured by

the magnetic meter. 13. Adjust the 2nd pressure reducing valve so that 24 psi enters the Test Valve. If

necessary, adjust the pilot valve so that it delivers 13 psi 14. Repeat step (12) in 1 psi increments until the pilot valve is wide open, and it can’t

deliver 13 psi d/s. NOTE: this can go fairly fast – just reduce the inlet pressure to the test valve until the downstream pressure drops and remains below 13 psi. The flow rate should also drop (~5-15 GPM). Then slowly increase the u/s pressure (likely by a half a psi or so) until it just barely delivers 13 psi and the right GPM. 15. Record the precise inlet pressure, the 13 psi, and the flow rate. 16. Then drop the pressure into the test valve by 1 psi. Adjust the flow rate to 60 GPM

with the flow control valve. Record the P d/s of the test valve. 17. Drop the pressure into the test valve by 1 more psi. Adjust the flow rate to 60 GPM

with the flow control valve. Record the P d/s of the test valve. 18. For each test valve, steps 1-15 should be repeated for the following additional flow

rates: 100, 200, 300, 400, and 500 GPM



ATTACHMENT B Valve Testing Measurement and

Uncertainty


Irrigation Training & Research Center P a g e | B-1

Attachment B Valve Testing Measurement and Uncertainty

The valve testing focused on two types of measurements: pressure and flow rate. These physical characteristics were measured directly with the following devices: 1) Pressure

a. Inlet pressure transducer: KPSI Series 27 0-100 psi (0.25% full-scale accuracy) pictured in Figure B1.

Figure B1. Inlet pressure transducer, KPSI Series 27

b. Inlet pressure gauge: Ashcroft 0-100 psi for redundancy only, pictured in Figure B2 across from the pressure transducer

Figure B2. High quality Ashcroft pressure gauge

c. Outlet pressure transducer: KPSI Series 27 0-30 psi (0.25% full-scale accuracy) as shown in Figure B3.

Figure B3. Outlet pressure transducer, KPSI Series 27



2) Flow rate: Seametrics AG2000 magnetic meter (+/- 1% accuracy) as pictured in Figure B4.

Figure B4. Seametrics AG2000 magnetic flow meter

The signals from these devices are measured by a high-quality, industrial SCADAPack350 programmable logic controller (PLC) featuring a 14-bit analog-to-digital converter, as shown in Figure B5.

Figure B5. SCADAPack 350 in enclosure



The PLC converts these 4-20 mA and pulse signals to pressures and flows respectively, which are then displayed through a PC human machine interface (HMI) for the tester to observe and take data points. These data points are then manually entered into a spreadsheet for graphing and analysis purposes, while the PLC is continuously data logging all inputs at 2-second intervals. The HMI workstation is shown in Figure B6.

Figure B6. Valve testing HMI

The HMI displays averaged values for flow and pressures at 1-second and 10-second intervals. The combination of virtually instantaneous readings for adjustments between data points and the longer average for data point verification enables efficient and accurate data collection. Calibration and Uncertainty

The pressure transducers and gauges were calibrated using a Druck DPI610. Because this high-quality laboratory grade pressure controller is capable of 0.025% full-scale accuracy, it can easily verify and maintain the accuracy published by KPSI (0.25%). Uncertainty analyses were completed for all valve testing measurements and the results are summarized in Table B1.

Table B1. Valve testing measurement uncertainty

Measurement Uncertainty

Inlet Pressure +/‐ 0.13 psi

Outlet Pressure +/‐ 0.04 psi

Flow Rate +/‐ 1.05% of reading



ATTACHMENT C 2-Way vs. 3-Way Pilots


Irrigation Training & Research Center P a g e | C-1

Attachment C 2-Way vs. 3-Way Pilots

Valve Operation Automatic hydraulic pressure regulating valves regulate their outlet pressure by increasing or decreasing the cross-sectional area of the water flow channel. This action directly affects the pressure loss across the valve body and subsequently the outlet pressure. The cross-sectional area of the water flow channel is determined by the position of the (direct or indirect) diaphragm, an elastic sheet typically constructed of rubber. The diaphragm is subjected to a differential water pressure: the pressure at the valve body inlet (plus the kinetic energy of flowing water) is applied to the bottom of the diaphragm, and a controlled water pressure is applied to the top of the diaphragm. A large spring also applies pressure downward on the diaphragm. A pilot valve directly controls the water pressure applied to the top of the diaphragm. The pilot valve houses a pilot spring, its own small diaphragm, and a spool. The position of the spool directs water to different passages and subsequently through tubes to the top of the diaphragm (bonnet). All pilot valves can increase or evacuate water pressure from the bonnet. The numerical operator in pilot descriptions (“2-way” and “3-way”) represents the number of spool positions inside of the pilot. Both types of spools have the following positions:

1) Filling the bonnet: Water from the valve body inlet is directed to the bonnet to decrease the cross-sectional area of the water flow path, thus decreasing the outlet pressure

2) Evacuating the bonnet: Water from the bonnet is evacuated, thus increasing the water flow path area and increasing the outlet pressure

3-way pilots have a third “rest” position, were all water movement into and out of the bonnet is stopped. The key difference between 2-way and 3-way pilots is that 3-way pilots evacuate bonnet pressure (water) to atmosphere. This allows the bonnet to more or less fully open, as only the spring is pushing down while the full inlet pressure is opening the water flow path. In contrast, 2-way pilots vent to the outlet side of the valve body, thus always having a lower pressure differential across the bonnet and never fully opening.



3-Way Pilots: A 3-way pilot allows the valve to be operated with a pressure loss equivalent to an

open valve body. When fully open the pilot itself does not inherently introduce additional friction loss.

In “auto mode” the 3-way pilot controls the flow of water (i.e., pressurizing) to the top of the valve diaphragm in 3 discrete operations. These operations are based upon a three-way spool inside the base of the pilot valve with these functions:

o Closing the valve: When the d/s pressure, acting on the pilot diaphragm, can overcome the pilot spring force the spool moves and connects the u/s pressure to the bonnet

o Static: When the d/s pressure, acting on the pilot diaphragm, matches the pilot spring force the spool moves into a static mode.

o Opening the valve: When the d/s pressure, acting on the pilot diaphragm, creates a thrust force less than the pilot spring pressure, the valve vents/empties the bonnet to atmosphere. If the valve continues to open, the bonnet pressure can be decreased to atmospheric pressure which allows the valve to fully open.

Figure C1. Bermad plumbing diagram from 100 Series

Notes:

With this design, it is difficult for the valve to hold a constant pressure as the inlet pressure changes. ITRC testing determined that these valves may be able to hold within +/- 1-1.5 psi when they are turned on and off.

For a 9 psi emitter (avg P), this variation can cause a drop in field (system) DU from an expected 0.93 down to as low as 0.88.



Figure C2 estimates the 3-way pilot control techniques as a function of bonnet pressure versus time.

Figure C2. Theoretical regulation of outlet pressure after an inlet pressure increase

With 3-way pilots, the best way to set them is to adjust the pressure. Then shut off the valve. Then turn the valve on again and check the pressure. If it isn't the target, repeat the procedure until it's correct.

2-Way Pilots: A 2-way pilot introduces considerably more friction loss in the valve. Evidently, it

keeps the valve partially closed even when it is “wide open”. In “auto mode” the 2-way pilot controls the flow of water (i.e., pressurizing) to the

top of the valve diaphragm in two discrete operations. These operations are based upon a two-way spool inside the base of the pilot valve with these functions:

o Closing the valve: When the d/s pressure, acting on the pilot diaphragm, can overcome the pilot spring force the spool moves and connects the u/s pressure to the bonnet

o Opening the valve: When the d/s pressure, acting on the pilot diaphragm, creates a thrust force less than the pilot spring force the spool moves and vents the bonnet to the d/s side of the valve.

Because the 2-way pilot must vent to a pressurized d/s port, the valve is not able to fully creating an inherent minimum loss across the valve.

With 2-way pilots, the bonnet pressure is continuously being pressurized and vented, requiring a small but consistent flow through the pilot/bonnet creating an increased potential for plugging of the u/s tubing filter.

The advantage of the Bermad 2-way pilot is that there is virtually no hysteresis. Additionally, also if the inlet pressure changes, the discharge pressure does not.

12.2

12.4

12.6

12.8

13

13.2

13.4

13.6

13.8

14

14.2

0 10 20 30 40 50 60 70 80

Regulated Outlet Pressure (psi)

Time (sec)



Published Valve Losses

It also appears that the published valve losses are always without a pilot installed (i.e., with the valve body only). For Bermad valves, losses through valves with 3-way pilots are published without pilots (as they can fully open) regardless of the presence of a pilot. However, for valves with 2-way pilots, Bermad publishes similar valve loss tables with a “2-way circuit ADDED HEAD LOSS” for velocities under a given threshold. See Figure C3.

Figure C3. Bermad published losses

low-pressure testing: pressure regulating valves

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