NATIONAL BUREAU OF STANDARDS REPORT

8331

A Study of the Characteristics

of

Refrigerant-Pressure-Actuated Water Regulating Valves

for Refrigerant Condensers

by

Selden D. Cole

Clinton W. Phillips

Paul R. Achenbach

to

Mechanical Engineering Division

Quartermaster Research and Engineering Command

Natick Laboratories, U. S. Army

Natick, Mass.

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT NBS REPORT

1003-20-10435 April 4, 1964 8331

A Study of the Characteristics

of

Refrigerant-Pressure-Actuated Water Regulating Valves

for Refrigerant Condensers

by

S. D. Cole, C. W. Phillips, and P. R. Achenbach

Mechanical Systems Section

Building Research Division

to

Mechanical Engineering Division

Quartermaster Research and Engineering Command

Natick Laboratories, U. S. Army

Natick, Mass.

IMPORTANT NOTICE NATIONAL BUREAU OF S

for use within the Government, and review. For this reason, tl whole or in part, is not authi Bureau of Standards, Washing

the Report has been specificall

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST)

on October 9, 2015.

ess accounting documents intended

s subjected to additional evaluation

e listing of this Report, either in he Office of the Director, National

iy the Government agency for which

copies for its own use.

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

A STUDY OF THE CHARACTERISTICS

OF

REFRIGERANT- PRESSURE-ACTUATED WATER REGULATING VALVES

FOR REFRIGERANT CONDENSERS

by

S B. Cole, C. W. Phillips, and P. R. Achenbach

1 . 0 Introduction

At the request of the Quartermaster Research and Engineering

Command, the National Bureau of Standards investigated the performance

characteristics of refrigerant-pressure-actuated valves designed for

regulating the flow of water through refrigerant condensers. This

type of valve, widely used in water-cooled refrigerating systems, has

two principal functions, namely, (a) to maintain a refrigerant con- densing pressure in the compression system that will produce an adequate flow of liquid refrigerant through the expansion device, and

(b) to conserve water. These same purposes can be accomplished by

temperature-actuated valves which control the condenser water flow

in response to the temperature of the refrigerant in the condenser

or to the difference in water temperature between condenser inlet and

outlet. However, each type of valve has somewhat different operating

characteristics

A proposed Military Specification, "Valves, Water Regulating,

Refrigerant R-12", prepared by the Quartermaster Corps and dated

August 31, I960 classifies these water-regulating valves as follows:

Size 1 - 3/8 inch National Pipe Thread (NPT) , 6 gallons

per minute (GPM) capacity

Size 2-1/2 inch NPT, 10 GPM capacity

Size 3 - 3/4 inch NPT, 25 GPM capacity

In addition, the specification incorporates material requirements

designed to provide strength, durability, corrosion resistance, stability of performance, and ease of maintenance and repair.

A proposed Military Standard, "Valves, Water Regulating, Refrigerant R-12", also prepared by the Quartermaster Corps and dated August 31, 1960 cites the above classification and includes the following rating conditions:

Condenser Hot Gas Pressure to be Maintained 126.55 psig

Pressure Drop across Valve for Rated Capacity 25 psig

Regulator Opening psig below Condenser Pressure 25 psig

Range of Operating Pressures 65 to 200 psig

Allowable Water Pressures 125 psig (Max), 35 psig (Min)

Maximum Water Temperature in Condenser Based on Temperature Rise in Condenser of 10F - 85F.

- 1-

The principal purpose of this investigation was to study the

performance characteristics of refrigerant-pressure-actuated watervalves that are of significance with respect to the two broad functions of refrigerant condensing pressure control and water conservation, and included the following characteristics:

(a) The range of condensing pressure adjustment provided by

the valve.

(b) The change in condensing pressure required to move the

valve from fully closed to fully open position for a range of inlet water pressures.

(c) The water flow rate through the valve in its fully open

position for a range of pressure drops across the valve.

(d) The hysteresis in the control mechanism on rising and

falling condensing pressures.

(e) The difference between the condensing pressure required

to commence opening the valve and that required to fully

stop the water flow.

(f) The effect of inlet water pressure on the condensing

pressure required to open and close the valve for a given setting of the adjustment spring.

Pressure-actuated valves of 3/8-inch, 1/2-inch, and 3/4-inch

pipe size from each of three valve manufacturers were used for the

study. The relation of condensing pressure to water flow rate was observed for each valve for three settings of the adjustment spring

and for three values of water pressure drop through the valve

In addition, the results obtained from the test specimens were

compared with the requirements of the proposed Military Specification

and Military Standard, as a basis for possible revision of these

documents and as a basis for suggesting new design criteria to the

manufacturers of this type of valves

2 . 0 Descr ipt ion of Test Specimens

Nine refrigerant pressure-actuated water flow regulating valves

submitted by Quartermaster Research and Engineering Command were investigated. These valves were manufactured by the following companies

1. Controls Company of America, Milwaukee, Wisconsin

2. Marsh Instrument Company of America, Skokie, Illinois

3. Penn Controls, Inc., Goshen, Indiana

The valve sizes (nominal N.P.T.), and manufacturer's identification were as follows:

- 2

-

Mfr

Nominal Pipe

Size, In.

Manufacturer 1 s Identification

CC of A 3/8 Device 70365-108, Mod. 65A

1/2 Device 70265-115, Mod. 65A

3/4 Device 70265-116, Mod. 65A

Marsh 3/8 Type 56-30

1/2 Type 56-30

3/4 Type 56-30

Penn 3/8 Type 246P93AR, Mod. 2300

1/2 Type 246P04AR, Mod. 2300

3/4 Type 246P06AR, Mod. 2300

All of the valve specimens used a bellows-type power element re- sponsive to condensing pressure of the refrigerant to modulate the

degree of valve opening by opposing the closing action of an adjustable spring mechanism. The spring tension could be adjusted by turning an adjusting stem projecting from the spring assembly. The bal- ance of forces between the spring, the refrigerant power element and

inlet and outlet water pressures determined the position of the regulating valve disk.

The valves were intended for use with refrigerant R-12 and were

3/8 inch, 1/2 inch, and 3/4 inch in size, based on the female pipe

threads at the inlet and outlet water openings. The screw-type spring

adjustment and the bellows-type power element were at opposite ends

of the valve body.

Each power element was provided with a small-bore soft-copper

tube, commonly called a capillary tube, about 30 inches long with a 1/4-inch SAE flare nut for connection to the source of refrigerant

condensing pressure. Each spring adjustment mechanism was provided

with a suitable end to receive a simple adjusting tool, or could be

positioned by hand. The valves were designed to be installed in any

position. The rated refrigerant pressure ranges for the three makes

were

Marsh

Penn

CC of A

60 to 270 psi

70 to 260 psi

65 to 300 psi

- 3-

The maximum exterior dimensions of the nine valves are listed in

table 1. In this table the length ij the distance from the face of

the water inlet to water outlet boss, trn. height is the distance from

the base of the power element capillary tuK (not including the strainrelief device) to the end of the spring adjustment means, and the

width is the exterior dimension at right angles to the length and

height

Table 1

Maximum Exterior Dimensions

of Nine Water Valves, Inches

Valve Nominal Capillary

Make Size Length Height Width Tube Length

CC of A 3/8 2 9/16 5 1 5/8 32

1/2 3 1/4 6 3/8 2 1/4 32

3/4 3 1/4 6 1/4 2 1/4 32

Marsh 3/8 2 13/16 5 1/8 2 32

1/2 3 3/16 c: 5/8 2 31 1/2

3/4 3 3/8 6 1/4 2 1/4 31

Penn 3/8 2 13/16 r

1 5/8 30

1/2 3 3/16 6 5/16 2 30

3/4 3 9/16 T1 / 8 2 2/6 30 1/2

Figures 1, 2, and 3 show features of the three makes tested

2 . 1 Construction of Controls Company of America Valves

Figure 1 is a photograph of the 3/8-, 1/2- , and 3/4-inch valves

manufactured by the Controls Company of America. The 1/2- inch size

has been disassembled to show the relation of the parts. The valve

body is shown near the left center of Figure 1 and just below it is

the main valve disk or sliding block. This block fits over two projections on the cross arm fastened to the push rod between the two

rubber fabric diaphragms which are also fastened to the pushrod.

This assembly is shown just below the sliding valve disk in Figure

1. To assemble, the push rod and one diaphragm are forced through

the valve body so that there is a diaphragm above and below the

valve body. The bellows-type power element is held tight against

the diaphragm with four screws. On the top side, the retainer plate

covers the diaphragm and in turn is covered with the cup, spring and cover forming the spring adjusting assembly. This assembly is attached to the valve body by four screws. Spring compression adjustment is accomplished by turning the square slotted stem projecting

from the end of the spring retainer.

- 4-

The sliding-block valve disk is held against the valve orifice

or seat by the inlet water pressure and is held in alignment by the

push rod guided in turn by the diaphragms and retaining plates.

The 3/8-inch valve has one valve orifice slot and the 1/2- and

3/4-inch sizes have two valve orifice slots, each sealed by one of

two bars of the sliding-block valve disk when the valve is closed.

According to literature furnished by the manufacturer, the valve

seat was stainless steel, the valve disk was called a "sliding graphitar block", and the valve body was cast brass.

2 . 2 Constru c tion Details o f Marsh Valves

Figure 2 is a photograph of the three Marsh valves with the 1/2-

inch size disassembled to show the approximate relative position of

the parts. Shown near the left center of the figure is the globetype valve body. The seating surface of the replaceable valve seat

is not visible because the body has been inverted to show the two

slots in the body cavity that guide the two projections of the pushrod assembly pictured just above the valve body. The rubber fabric

diaphragm with the hole in the center is held to the pushrod assembly

by a machine screw and washer. The diaphragm is covered by the metal

upper retainer covered in turn by the be blows -type power element con- taining the bellows pushrod. Four screws hold the power element to

the valve body. Pictured below the valve body, the valve disk and

disk retainer unit is screwed to the push rod assembly and is in con- tact with the solid rubber fabric diaphragm. The diaphragm is cov- ered with the retainer and guide plate, and the spring push-plate

assembly is inserted into the guide plate. The concentric inner and

outer springs are placed over the rod of the push-plate and inserted

in the ad justing- cap assembly attached to the valve body by four screws

Spring compression adjustment is accomplished by rotating the

knurled cap by hand or by wrench or screwdriver

The valve seat appeared to be stainless steel and the valve disk was a rubber-type material inserted in a metal retainer.

The direction of water flow through the valve was such that it

opposed the closing motion of the valve disk.

2 . 3 Construction Details of Penn Valves

Figure 3 shows the three Penn valves with the 1/2-inch size

disassembled to illustrate the relation between parts. Just below

the left center of the figure is the valve body and above it is the

valve disk and retainer assembly. TWo each of the four rubber

- 5-

fabric type diaphragms cover the top and bottom openings, respectively, of the body and are held in place to make a watertight fit

at each end of the valve-disk assembly by means of the long machine

screw which extends through the entire pushrod assembly and screws

into the hexagonal power-element pushrod shown below the valve body.

The power-element assembly is held in place with four screws, and

seals one pair of diaphragms against the valve body. The two diaphragms on the spring end are held in place by the pushrod guide

plate which forms the base for the spring adjuscment assembly, con- sisting of the spring push-plate, spring, and spring retainer. The

spring retainer was held to the body by the four long screws. Spring adjustment is accomplished by turning the square stem projecting from the end of the spring retainer.

The replaceable valve seat appeared to be of brass and the

valve disk was a rubber- type material in a brass retainer.

The indicated direction of water flow through the valve was

such that the flow of water opposed the closing motion of the valve

d i sk

3 . 0 Description of Test Apparatus

The valve specimens were connected in turn to a water supply

of suitable pressure and capacity wicn pressure-regulating valves,

pressure gages, and valves to control and measure the performance

characteristics as indicated diagrammatically in Figure 4. The

discharge water from the test specimen was collected in a tank

mounted on a platform scale. Stop watch readings were taken to

determine average rates of water flow. Compressed dry nitrogen was used to provide the desired power element pressures.

Referring to Figure 4, the nipples, tees, and unions between

the test specimen and the reducing couplings on the inlet and outlet

sides of the specimen were of the same nominal pipe size as the

threaded connections of the specimen itself. The distance between

the two unions was kept constant at about 18 inches by selecting

pipe nipples of different lengths for the various specimens. The

pipe nipples between the unions and reducing couplings on either

side of the test specimen were about one foot long. The pipe and

fittings between the reducing couplings and the supply and discharge

ends of the test apparatus were of nominal 2-inch size. The pres- sure gage on the inlet side was a calibrated Bourdon-type test gage

with a range of 0 to 300 psi, a 6-inch dial, and 2 psi graduations,

whereas that on the outlet side was a calibrated Bourdon-type gage

with a range of 0 to 100 psi, a 4-inch dial, and one psi graduations.

- 6

-

The capillary tube to the power element of the test specimen was connected to a cylinder of dry nitrogen gas through a pressure-reducing

valve. Pressure at the inlet to the capillary tube was measured with

a gage of the same range and size as that at the water inlet to the test

specimen. The pressure-reducing valve on the nitrogen cylinder was adjusted to maintain the desired pressure at the inlet to the capillary tube. A vent valve on the nitrogen line was used in some tests

to waste a little nitrogen gas in order to maintain a floating con- dition in the pressure-reducing valve.

4.0 Test Procedure

Each specimen valve was similarly installed in the test apparatus

as shown in Figure 4. Each valve was operated at three settings of the

pressure-adjusting spring and three inlet water pressures for a total

of nine tests for each vaive. The three spring settings were:

1. Full retraction of spring adjustment mechanism

2. A setting which produced an initial valve opening at about

80 psig nitrogen pressure on the power element, and 30 psig

inlet water pressure.

3. A setting which produced an initial valve opening at 150 to

160 psig nitrogen pressure on the power element, in most

cases, and 30 psig inlet water pressure.

The three inlet water pressures were:

1. 30 psig

2. 60 to 70 psig

3. 90 to 100 psig

In addition, the water flow rate was measured for a range of water

pressure drops from 0 to above 80 psi with the valve set for an open

position. For these tests, the open position was obtained by maintaining a nitrogen gas pressure of 300 psig in the power element and

the spring adjustment was in the fully-retracted position.

The following procedure was used for obtaining the three spring

adjustments described above. The spring adjustment device was first

set in the fully-retracted position. The minimum gas pressure re- quired to open the valve was determined by slowly increasing the

nitrogen gas pressure, starting at 0 psig, and observing the pressure

at the instant the inlet water pressure started to drop from an initial value of 30 psig. This pressure drop indication was made very

sensitive by closing the shutoff valve on the inlet water line (see

Fig. 4) with water at 30 psig pressure trapped between the inlet

water shutoff valve and the test specimen. A similar procedure was

used for the two higher settings of the spring adjustment. Several

-

7

-

adjustments of spring compression were usually required to obtain

the desired nominal opening gas pressures of 80 and 160 psig. Once

the desired opening pressure was obtained, the same spring compression setting was used for all tests at that nominal opening pressure.

At each of the three settings of the spring adjustment, water

flow rate measurements were made at three inlet water pressures-- JO

60 to 70, and as near to 100 psig as the laboratory supply could provide. While each of these inlet water pressures was maintained on

the upstream side of the valve specimen, the outlet valve on the

downstream side was manually adjusted to maintain a pressure of 10

psig at the outlet of the test specimen, so the pressure drop across

the valve was 10 psi less than the entering water pressure at all

times. This was done to test all the valves under similar conditions

and to simulate, for each data point, the resistance to the flow of

water of a condenser downstream of the test valve.

Each series of measurements at a particular inlet water pressure was conducted generally in the following manner. After determining the minimum nitrogen gas pressure required to open the valve

under test, as described above, the gas pressure on the power element

was raised an increment of 5 psi, the inlet water shutoff valve was opened, and the outlet water shutoff valve partially closed until

10 psig was indicated by the gauge on the outlet side of the test

specimen. When the conditions had stabilized, a moving tare weight

was obtained for the water receiving tank and the time required,

not less than 2 minutes, to collect an even multiple of 100 pounds

of water was recorded, using a stop watch. The stop watch was started as the tare weight tipped the scale arrn and stopped when

the collected water again tipped the scale arm, with the necessary

added weights. The receiving tank was then drained while the gas

pressure was increased an increment of 5 to 10 psi. The water

pressures were adjusted again to the desired inlet and 10 psig

outlet, and when stabilized, the weighing procedure was repeated.

This procedure was repeated at selected increments of higher nitrogen

pressure up to a maximum of J0Q psig.

Water flow races were then similarly determined for descending values of nitrogen pressure from ^00 psig to a pressure which

allowed the valve to close. The nitrogen pressure in the power

element of the valve was reduced by manual operation of the vent

valve shown in Figure 4. The water valve under test was considered

closed at the final 5 psi incremental setting of nitrogen pressure

at which no water flowed from the outlet pipe into the receiving

tank after the previous higher increment at which a very slow flow was obtained. In most cases, this procedure resulted in a definite

closing pressure determination within a 5 psi range.

- 8 -

5 . 0 Test Results

5 . 1 Water Flow Rate at Full-Open Valve Position

Water flow rates were determined for the nine valve specimens

for a range of water pressure drops with the valve in the open position produced by a high power element pressure. The water flow rate

is plotted in Figures 5 and 6 as the dependent variable against the

pressure drop across the valve in the water circuit. In Figure 5,

each group of three curves shows the performance of the three valve

sizes from one manufacturer. In Figure 6, each group of three curves

shows the performance of three similar-sized valves, one from each

of the three manufacturers.

The water flow rate data shown in Figures 5 and 6 were obtained

with the spring adjustment device fully-retracted and a nitrogen gas

pressure on the power element of 300 psig. For most of the valves,

this produced a maximum valve opening. For the 1/2- inch and 3/4- inch

valves manufactured by Controls Company of America, the maximum water

flow rate was obtained with a valve disk travel slightly less than

the maximum possible travel of the disk pushrod assembly. The values

plotted in Figures 5 and 6 for these two valves are the water floi*? rates obtained with the maximum travel of the valve disk pushrod.

Each value of water flow rate was determined by collecting,

for a measured duration of about two minutes, the water discharged

through the valve at the various inlet water pressures against a constant outlet water pressure of 10 psig. The water pressure drop across the valve was increased by increments of 10 psi to a maximum

of about 100 psig water pressure at the inlet side of the valve.

Figure 5 indicates that the water flow rate curves for the

different-sized valves of each manufacturer, were generally parabolic in shape and that water flow rate increased with valve size,

other conditions being equal. It was determined that the water

flow rate for each valve in the full-open position was essential!}?

proportional to the squat e root of the water pressure drop across

the valve.

Figure 6 provides a comparison of the water flow rates of

valves of the same nominal pipe size from different manufacturers.

It will be noted that the 1/2-inch size valves from the three manu- facturers had almost the same capacity throughout the range of

pressure drop employed in the tests. For example, at a water pressure drop of 75 psi the water flow capacity of the three 1/2-inch

valves differed by only 10 percent, with the Penn valve having the

highest capacity and the Controls Company of America valve, the

lowest capacity.

- 9-

In the 3 / 8 -inch size, the water flow capacity of the three

makes of valves differed widely. At a water pressure drop of 25

psi the highest capacity was 1.8 times the lowest, whereas at a water pressure drop of 75 psi this ratio was 2.1. In this size

valve, the Penn valve also had the highest capacity and the Controls Company of America valve had the lowest capacity.

For the three 3/4-inch size valves, the ratio of the highest

water flow capacity to the lowest capacity ranged from 1,24 at a water pressure drop of 25 psi to 1.41 at a pressure drop of 75 psi.

In this size valve, the Marsh valve had the highest capacity and

the Controls Company of America valve had the lowest capacity.

It appears that the single orifice opening in the 3 / 8 -inch

valve of the Controls Company of America did not permit water flow

rates comparable to the 3 / 8 -inch globe-type valves of the other

two makes to the same degree that the double orifice opening permitted in the larger size valves.

5.2 Valve Performance for Modulated Water

and Refrigerant Pressures

The water flow rates of each of the nine valve specimens for a range of refrigerant condensing pressure and at three settings of

the spring adjustment mechanism are shown graphically in Figs. 7 to

15, inclusive. In these figures the water flow rate is plotted as

a dependent variable against the refrigerant condensing pressure,

produced by the pressure of dry nitrogen gas in the power element

of the valve during these tests. In most cases the performance of

the valves was determined for both increasing and decreasing values

of refrigerant condensing pressure. The test procedures used in this

investigation were developed during the course of the tests of the

3 / 8 -inch valves, so the results on this size valve are not quite as comprehensive as those for the other sizes. Only the test results

of the 3 / 8 -inch valves that were obtained by procedures essentially

similar to those finally used for the larger valves are Bhown in this

group of figures.

In each of Figures 7 through 15, the observed data are presented

in three groups of curves corresponding to the three settings of the

spring adjustment mechanism, except in a few cases where the performance of the valve prevented completing the three series of tests.

Different symbols were used in the figures to show the results for

increasing and decreasing refrigerant condensing pressures, and also

for different pressure drops across the valves.

The several performance features of the refrigerant-pressureactuated water valves that were of interest in this investigation

included the following:

- 10 -

(a) The ratio of the change in water flow rate to the change in

refrigerant-condensing pressure in the central modulating range

of the valve, from about 10% to 90% of the maximum water flow

rate

(b) The total change in refrigerant condensing pressure required from

90% maximum water flow rate to valve shutoff.

(c) The opening and closing characteristics of the valves, from shutoff to about 10% of the maximum water flow rate.

(d) The water flow versus refrigerant condensing pressure characteristics from 90% to 100% of the maximum water flow rate.

(e) The frictional characteristics of the movable elements of the

valves, as indicated by the difference in water flow rate for

identical increasing and decreasing values of refrigerant con- densing pressure.

(f) The effect of supply water pressure on the performance of the

valves

An inspection of the curves in Figs. 7 to 15, inclusive, shows

that the water flow rate was approximately proportional to the refrigerant condensing pressure throughout a broad central range of water flow

rate, since the central portions of the curves approximate straight lines.

This approximation appeared to be less exact for the 3/8- inch Marsh valve

than for the other specimens, and appeared to be less exact for the lowest inlet water pressure than for the higher water pressures for several

of the specimens.

For purposes of analysis and discussion, each of the performance

curves in Figs. 7 to 15 can be divided into three sections, namely: the

section from valve shutoff to 10 percent maximum flow rate, the section

from 10 percent to 90 percent flow? rate, and the section from 90 percent

to 100 percent maximum flow/ rate. The first section indicates the opening and closing characteristics of the valve. The middle section com- prises the operating range of the valve and is the section in which the

water flow rate is most nearly proportional to the refrigerant condensing pressure. The third section reveals the operating characteristics

of the valve near its wide open position. For most of the specimens

tested, the change in refrigerant condensing pressure required to obtain

the last 10 percent of the maximum water flow rate was much larger than

that required for a similar increment of water flow rate in the working

range. For this reason it is considered undesirable to rate a water

regulating valve on the basis of its maximum water flow rate since it

would require an abnormally high refrigerant condensing pressure to produce the maximum water flow rate.

- 11 -

5.2.1 Sensitivity Factor

As used in this report, the ratio of the change in water flow

rate to the change in refrigerant condensing pressure in the operating

range of a water regulating valve from 10 percent to 90 percent of

the maximum water flow rate is defined as the 1 sensitivity factor 1 for the valve. It represents the change in water flow rate in gallons

per minute per unit change in refrigerant condensing pressure expressed

in pounds per square inch. The sensitivity factor is directly related

to the slope of the curves in Figs. 7 to 15 in the working range of

the valves, that is, a steeper slope represents greater sensitivity

and vice versa.

The water flow rates at 10%-, 90% and 100% maximum flow rate,

the corresponding refrigerant condensing pressures at these flow

rates and at valve opening and closing, and the sensitivity factor

for each valve specimen are summarized in Tables 2-4, inclusive.

Study of these tables indicates that the sensitivity factor differed

only slightly with the direction of change of the refrigerant con- densing pressure, and only slightly for the range of refrigerant

condensing pressure from the minimum setting to the high setting of

the pressure adjusting spring.

Table 5 is a summary of the sensitivity factors for the nine

valve specimens, in which all the values obtained for a given supply

water pressure range were averaged for each valve. This table shows

a variation of about 2 to 1 in the sensitivity factors of the different models of the 3/8-inch valves at a supply water pressure of 30

psig and a variation of nearly 3 to 1 for the same size valves at

the highest supply water pressure. The sensitivity factors for the

two larger size valves varied from 15 to 40% among the different

models over the range of supply Twater pressures used. For any given

valve specimen, the sensitivity factor tended to increase as the

water supply pressure increased, but the rate of increase in sensitivity was not consistent among different specimens. The sensitivity

factor was as low as 0.1 gpm per unit change in refrigerant condensing

pressure for one make of 3/8- inch valve and ranged upward to about

1 gpm per unit change in refrigerant condensing pressure for all

three 3/4-inch valves at the highest supply water pressure.

5.2.2 Refrigerant Condensing Pressure

in Operating Range of Valves

The sensitivity factor for any given make of valve increased rather

sharply with the size of the valve. This characteristic might be anticipated since the larger valves had larger water passages. However, the

higher sensitivity factors for the larger valves does not necessarily

indicate that the operating levels of refrigerant condensing pressure

would be lower for larger capacity installations since these require a

- 12 -

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higher water flow rate. Table 6 summarizes the decrease in refrigerant

condensing pressure to change the water flow rate from 90 percent of the

maximum rate to valve shutoff. The values in Table 6 were taken from

Tables 2-4, inclusive, from the data observed at the medium setting of

the pressure adjusting spring, that is, a valve opening pressure of

about 80 psig; and for decreasing values of refrigerant condensing pressure in most cases. Table 6 shows a considerable variation in the re- frigerant pressure change required to move the valve from 90 percent

maximum flow rate to the closed position. This pressure increment was

higher for the Marsh valves than for the other two makes in 5 out of

the 6 cases for which comparisons could be made. This pressure increment was significantly higher for the 3/8-inch size valve of the Controls Company of America than for the other two sizes of the same make;

whereas this pressure increment was highest in the 1/2-inch size of the

Penn valves. Reference to Tables 2-4 inclusive show that the refrigerant condensing pressure at 90 percent maximum flow rate would range from

108 psig to 177 psig for eight of the nine valve specimens on which data

were observed when they were set for an opening refrigerant condensing

pressure of 80 psig.

5.2.3 Opening and Closing Character Istlcs

It was observed during the tests that the refrigerant condensing

pressure had to be reduced to a somewhat lower value to completely stop

the water flow in some instances than that required to initiate water

flow as the refrigerant condensing pressure was rising. This characteristic is illustrated for the 1/2-inch and 3/4-inch valves of each of the

three manufacturers by the plotted data at zero water flow rate in Figs.

8 and 9, 11 and 12, and 14 and 15. A summary of the difference between

the opening and closing pressures for the 1/2-inch and 3/4-inch valves

is reported in Table 7.

Table 7 indicates that the difference between the opening and closing pressures for the two valves manufactured by Controls Company of

America was significantly greater than for the other two valves. The

number of possible comparisons with the Marsh valves was limited because

malfunctioning of these valves caused early termination of the tests.

The valve action in the Controls Company of America specimens was obtained by a slotted movable block sliding over a slotted stainless steel

seat with the supply water pressure holding the block against the seat.

In the Marsh and Penn valves the supply water exerted forces opposing

both the spring pressure and the power element pressure but did not

involve sliding further between the moving valve element and the seat.

The difference in construction of the valves may account for the variations in opening and closing performance shown in table 7.

- 14-

Table 7

Difference between Opening and Closing Pressures of

1/2-inch and 3/4-inch Valves, psi

Supply Water Pressure, psig

Valve Manufacturer

30 1 60 to 70 1 90 to 100

Setting of Pressure Ad justing Spring

Min Med. High Min. Med. High Min. Med. High

1/2-inch Valves

Controls Company of America 5 7 13 \ 8 11

t 21 ; 12 13 25

Marsh Instrument Co. - 0

-

; - 0

- 2

- Penn Controls Inc. 0

- 5 ' 1 0 1' 1 4 12

3/4-inch Valves

Controls Company of America 8 3 16 ; 14 10 14 i 13 14 24

Marsh Instrument Co. 0

- -

; 0

- - - Penn Controls Inc. 5 2 5 * 1 2 2

* 0 1 5

The characteristic curves showing the relation between water flow rate

and refrigerant condensing pressure near shutoff exhibited three distinct

shapes as illustrated most clearly in Figs. 7, 10 and 13, although some other

figures have similarities to these. In three of the curves in Fig. 7 a definite discontinuity in the characteristic curves occurred at water flow rates

of about 1, 2, and 21/2 gpm, respectively. The valve was less sensitive to

change in refrigerant condensing pressure below these flow rates in these

three instances, although a similar phenomenon was not evident in every test

of this valve.

In Figure 10 the characteristic curve flattened out significantly near

shutoff for several of the tests. In these instances this 3/8-inch Marsh

valve permitted a trickle of water to pass until the refrigerant condensing

pressure was lowered well below the value that would be obtained by extrapolating the main portion of the characteristic curve. The reason for this

performance was not determined, but it could be caused by foreign matter On

the valve seat or a slight misalignment of the moving elements.

In Fig. 13 the slope of the characteristic curve was maintained essen- tially constant down to shutoff. Similar results were observed in some tests of the 3/4-inch Penn valve, as illustrated in Fig. 15.

The shape of the characteristic curve near shutoff is important with

respect to water leakage through the valve when the refrigerant unit is not

running. If a water regulating valve has a flattened characteristic curve

near shutoff, the pressure adjustment spring must be set at a higher value

for any given water temperature to prevent water leakage when the unit is

not running. This causes the refrigerating unit to operate at a higher com- pression ratio and less efficiently than would be necessary if the water

regulating valve had a steep pressure curve at shutoff.

- 15 -

5.2.4 Maximum Flow Characteristics

The characteristic curves in Figs. 7-15 inclusive, showing the

relation of water flow rata to refrigerant condensing pressure, exhibited three different shapes in the range of flow rate from 90 to 100

percent of the maximum rate. The most frequent shape was a gradual

decrease of slope of the curve toward a horizontal line representing

the maximum water flow rate, as illustrated by Figs. 7, 10 and 13.

Illustrating a second characteristic shape, the water flow rate for

the 1/2-inch and 3/4-inch valves submitted by the Controls Company of

America reached a maximum value for an intermediate value of refrigerant condensing pressure and then decreased 10 percent or a little

more at higher condensing pressures as shown in Figs. 8 and 9. This

effect was apparently caused by an overtravel of the sliding valve

element past the position of best alignment of the openings in the

valve seat and the moving element at high values of refrigerant con- densing pressure. Figure 15 illustrates the third shape, a fairly

abrupt change from the proportional part of the performance curve to

the horizontal line representing maximum water flow rate.

The type of valve performance illustrated in Fig. 15 is probably

the most desirable performance near the maximum flow rate, because

the valve could be operated up to 100 percent of the maximum flow rate

with very little decrease in sensitivity. The 1/2-inch and 3/4-inch

valves of the Controls Company of America were also quite sensitive

up to the maximum flow rate, as shown in Figs. 8 and 9. However, if

the refrigerant condensing pressure continued to rise above the level

corresponding to the maximum water flow rate in a system equipped with

this type valve, the water flow rate would be reduced by 10 percent or more at the condition of greatest cooling requirement, and the system

would be unnecessarily penalized in operating efficienc}/.

It appears undesirable to operate valves with characteristic

curves similar to those shown in Figs. 7, 10 and 13 at the maximum

water flow rate because of the large increase in refrigerant condensing pressure required to attain the last 10 percent of the maximum

flow rate. Table 8 summarizes the increase in refrigerant condensing

pressure required to raise the water flow rate from 90 to 100 percent

of the maximum value. These data were taken from Tables 2-4 and Figs.

7-15, inclusive, and show an average value for each water supply

pressure and each setting of the pressure adjusting spring.

Table 8 shows that the 1/2-inch and 3/4-inch valves submitted by

Controls Company of America and the 3/4- inch Penn valve for water supply pressures above 60 psig required the smallest increase in re- frigerant condensing pressure to increase the water flow rate from 90

to 100 percent of the maximum value. The values were in the range

from 8 to 20 psig in most instances for these three cases. Table 8

- 16 -

Increase

in

Refrigerant

Condensing

Pressure

Required

to

Increase

Water

Flow

Rate

from

90

to

100

Percent

of

Maximum

Rate,

psi

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shows several instances where the required increase in condensing pressure was in the range from 60 to 110 psig. An examination of Figs. 7-

15 shows that these unusually high values corresponded to situations

where substantially 100 percent maximum flow rate was obtained with a more moderate rise in refrigerant condensing pressure, but there con- tinued to be a slight increase in water flow rate for greater increases

in condensing pressure, perhaps caused by an increased elastic deformation of some of the moving parts other than the springs. Most of the

values of pressure increase in Table 8 for all the 3/8-inch valves and

for the 1/2-inch Marsh and Penn valves were in the range from 20 to

55 psig.

5.2.5 Hysteresis on Reversal of Refrigerant

Condensing Pressure

Data were obtained on each of the 1/2- inch and 3/4- inch valves for

both increasing and decreasing values of the refrigerant condensing

pressure in the range from shutoff to maximum water flow rate. The re- sults for increasing and decreasing refrigerant condensing pressure are differentiated in Figs. 8, 9, 11, 12, 14 and 15 by using open and closed

symbols, and are also tabulated separately in Tables 2-4, inclusive.

An examination of the data in Tables 3 and 4 shows that the sensitivity factor and the change in refrigerant condensing pressure required

to change the water flow rate from 10 to 90 percent of the maximum flow

rate was comparable for increasing and decreasing values of refrigerant

condensing pressure. The variation in sensitivity factor and AP (10 - 90?/ flow) for increasing and decreasing refrigerant condensing pressures

was 10 percent or greater in 10 cases out of 43 cases where comparisons

were possible, and was less than 10 percent for the other 33 test con- ditions .

An examination of the difference in refrigerant condensing pressure

at 90 percent maximum water flow rate for increasing and decreasing values of refrigerant condensing pressure in Tables 3 and 4 shows that this

difference was negligible for the 1/2-inch and 3/4-inch Marsh valves,

it averaged from 4 to 6 psig for the two Penn valves of the same nominal

size, and it averaged 9 to 10 psig for the same size valves submitted

by Controls Company of America. These pressure differences represent

the smallest change in refrigerant condensing pressure, produced by a change in refrigerating load or a change in the condensing water temperature, that would cause a readjustment cf the valve position and a change in water flow rate.

The greater hysteresis in the valves of the Controls Company of

America may have been due to the design of the valves in which sliding

friction between the valve seat and moving element was involved in

- 18 -

every change in valve position, whereas in the other two makes the valve

was of a globe type in which the turbulence of the water flow would help

to overcome static friction in repositioning the moving valve element.

The importance of the hysteresis may be judged by the fact that the

product of the pressure change required to change the valve position

and the sensitivity factor for the valve indicates how much the water

flow rate may depart from a design value. For example, a valve with a pressure hysteresis of 10 psig and a sensitivity factor of 0.5 could be

using 5 gpm more water than required for limited periods of time when

the refrigerant condensing pressure was fluctuating.

5.2.6 Effect of Supply Water Pressure

on Valve Performance

A review of Table 5 shows that the sensitivity factor of all the

valve specimens increased for increased supply water pressure, but not

always throughout the whole range of water pressure. The decrease in

refrigerant condensing pressure required to change the water flow rate

from 90 percent maximum to shutoff also increased somewhat with increasing water supply pressure as shown in Table 6. The difference

between opening and closing pressures for the 1/2-inch and 3/4-inch

valves of the Controls Company of America increased with supply water

pressure in most instances, and for the Penn valves at some test con- ditions .

The sensitivity factor increases with water supply pressure because

the outlet water pressure was maintained constant for the tests and, as the data in tables 2-4 show, the refrigerant condensing pressure re- quired to obtain 90 percent maximum flow rate was only slightly affected

by supply water pressure. Thus the numerator of the ratio A Q/AP, defining the sensitivity factor, increased with increasing supply water

pressure while the denominator remained nearly constant.

The greater changes in refrigerant condensing pressure required to

move the valve between two fixed positions as the supply water pressure

was increased are probably related to the greater water pressure difference across the moving element of the valves, which caused greater sliding friction in the case of the specimens submitted by the Controls

Company of America and greater direct resistance to closure of the other

two makes of valves.

- 19 -
I. ;
6 . 0 Comparison of Valve Performance

with Military Standard Requirements

The requirements in the proposed Military Standard, summarized

in the Introduction, are interpreted to mean that water-regulating

valves for refrigerant condensers of 3/8-inch, 1/2-inch, and 3/4-inch

pipe size should provide water flow rates of 6, 10, and 25 gpm, res- pectively, with an increase in refrigerant condensing pressure not

to exceed 25 psi above a valve-opening condensing pressure of 101.55

psig for a water pressure drop of 25 psi between valve inlet and outlet .

The maximum water flow rate corresponding to a water pressure

drop of 25 psi between inlet and outlet of the test specimens can be

determined from Figs. 5 or 6. These values are summarized in Table 9

for comparison with the requirements stated in the proposed Military

Standard. It will be seen in Table 9 that the maximum water flow

rates ranged from 125% to more than 200% of the requirement for the

3/8-inch valves, averaged about 200 percent of the requirement for

the 1/2-inch valves, and ranged from about 115 percent to 150 percent

for the 3/4-inch valves.

If the valves were rated at 90 percent of the maximum flow rate

to avoid low sensitivity near the wide open position, as discussed

earlier in this report, three of the specimens would have less than

17 percent excess capacity and the other six specimens would have

from 30 to 100 percent excess capacity. The water flow rates cor- responding to 90% maximum are also shown in Table 9 for comparison

with the proposed Military Standard requirements.

The rise in refrigei'ant condensing pressure required to obtain

the water flow rates specified in the proposed Military Standard for

the various size valves with a water pressure drop of 25 psi is shown

in Table 10. These valves were obtained from the performance curves

in Figs. 7-15 by interpolating between the data for the low and medium

values of water supply pressure and between the medium and high settings of the pressure adjusting spring. It was found that the rise

in refrigerant condensing pressure required to obtain a given percentage of maximum water flow rate, i.e. a given fraction of maximum

valve opening, varied only a little with water supply pressure, and

with the setting of the pressure adjustment spring. Thus, the interpolation involved only small deviations from observed data. In a few

cases, extrapolation was necessary because the observed data did not

bracket the specified water pressure difference of 25 psi or the

specified valve opening pressure of 101.55 psig.

- 20 -
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The data in Table 10 indicate that the rise in refrigerant con- densing pressure required to produce the specified water flow rates was 26 psi or less for three of the nine valve specimens, and that it

ranged from 32 to 59 psi for the other six specimens. Thus, for an opening pressure of 101.55 psig, the operating level of condensing

pressure would range from about 118 to 161 psig for the various valve

specimens at the required water flow rate.

The rise in refrigerant condensing pressure required to obtain

90 percent of the maximum water flow rate for each valve with a water

pressure difference of 25 psi and a valve opening pressure of 101.55

psig is also shown in Table 10. These pressure increments ranged from

39 to 70 psi for the nine valves, indicating that undesirably high

operating pressures would occur in attempting to use 90 percent of

the maximum capacity of the valves.

7 . 0 Mechanical Performance of Valve Specimens

Some difficulties with chattering and water leakage developed in

two sizes of the Marsh valves during the tests.

Figure 11 shows the results obtained with the 1/2-inch valve

manufactured by Marsh Instrument Co. The first test runs were made

with a nominal valve opening pressure of 80 psig and with supply water

pressures of 30, 70, and 98 psig, followed in turn by a series with

minimum valve opening pressure, with the same three supply water pressures. At the test conditions indicated by "A" in Figure 11 with a minimum valve opening pressure and increasing values of refrigerant

condensing pressure, severe chattering of the valve occurred which

caused a water leak to develop at one edge of the diaphragm under the

power element assembly and water was discharged to the atmosphere.

The tests of this valve were terminated at this time.

Figure 12 shows the results obtained with two specimens of the

3/4-inch water-regulating valve manufactured by Marsh Instrument Co.

Both specimens developed water leaks after severe chattering in similar fashion to that described for the 1/2-inch valve from the same manufacturer

Test runs at increasing and decreasing refrigerant pressures were

made with the 3/4-inch valve submitted by the Quartermaster Research

and Engineering Command at the minimum opening refrigerant pressure

and at water supply pressures of 30, 70, and 93 psig. While the re- frigerant condensing pressure was being decreased during the run at

93 psig Supply water pressure, at the conditions indicated by "A" in

Figure 12, the valve chattered causing a water leak to develop. No

further capacity tests were made of this valve. Another valve of the

- 22 -

same make and model was obtained from a commercial supplier in Washington, D.C. During a test run at 98 psig supply water pressure with the

valve set to open at 80 psig refrigerant condensing pressure, this

valve chattered and developed a water leak at the conditions indicated

by "B" in Figure 12. No further capacity tests were made with this

valve. The curve for the second 3/4-inch valve extends above the

graph in Figure 12. It essentially leveled off at a water flow rate

of 68 gpm at a refrigerant pressure of 250 psig.

It is not known what caused these three valves to chatter and

develop water leaks in this manner. The chattering apparently produced dynamic pressures which forced water through the diaphragm seals

at an edge and at the valve stem permitting water to leak out at the

diaphragm seal between the power element assembly and the valve body.

The body screws were checked for tightness before each test, but not

the screw and washer on the valve stem. No mechanical damage was evident when the valves were disassembled after testing. The chattering

occurred both with and without a booster pump in operation and only at

supply water pressures in excess of 80 psig.

8 . 0 Discussion and Conclusions

The tests described in this report were made to explore the performance characteristics of pressure-actuated valves designed to regulate the flow of cooling water through refrigerant condensers. Commercial valves were used as test specimens, but the tests were not intended to be acceptance tests for commercial products.

Supply water pressures of about 30, 70, and 90 psig and valve

opening pressures of minimum, 80, and 160 psig were selected for the

tests to bracket the probable range of application and use. A con- stant water pressure at the valve outlet of 10 psig was selected to

simulate the pressure drop of a condenser and associated piping downstream of the valve, although it was recognized that the pressure drop

in any given condenser system would increase approximately as the

square of the water flow rate. The inlet water pressure was also kept

constant at all water flow rates although this condition would only

be approximated in actual use.

The investigation indicated that the following characteristics

of a pressure-actuated water-regulating valve were of importance in

meeting the functional purposes of such a valve:

(1) The maximum water flow rate of the valve versus water pres- sure drop through the valve.

- 23 -

(2) The sensitivity factor of the valve in the working range of

water flow rate. The sensitivity factor determines the

total change in refrigerant condensing pressure required to

move the valve element from a closed position to that of

design water flow rate.

(3) The tendency of the valve to leak water at refrigerant con- densing pressures below the opening pressure.

(4) The decrease in sensitivity of the valve near the wide open

position.

(5) Hysteresis in the moving valve element for increasing and

decreasing condensing pressures.

(0) The effect of supply water pressure and setting of the opening pressure adjustment on sensitivity, hysteresis, and

shutoff characteristics.

(7) The mechanical stability of the moving valve element against

chattering

(8) The possibility of overtravel of the moving valve element

past the position of optimum orifice alignment.

The series of tests on nine commercial valve specimens in three

nominal pipe sizes indicated the following conclusions:

(a) The pipe thread size of a valve is not a good indication of

its maximum water flow rate. In the 3/8- inch valves the

maximum water flow rate varied in the ratio of about 2 to 1

whereas the maximum water flow rates of the three 1/2-inch

valves differed by only about 10 percent.

(b) The sensitivity factor of the valves varied widely. The

water flow rate and maximum rise in refrigerant condensing

pressure specified in the proposed Military Standard indicated the following sensitivity factors between valve opening and specified water flow:

Nominal Valve

Size, in.

Sensitivity Factor

A Q/AP

3/8

1/2

3/4

0.24

0.40

1.00

- 24-

Only one of the 3/8-inch valves and two of the 1/2-inch valves

attained these average values of the sensitivity factor from valve

opening to the specified water flow rate as indicated in Table 10.

The test results indicated that the operating level of condensing

pressure would range from 118 to 161 psig for the several valves at

the water flow rates specified in the proposed Military Standard.

The sensitivity of a valve can be increased by increasing the

length or diameter of the cylindrical spring, decreasing the diameter

of the spring wire, or increasing the diameter of the power element.

Economic considerations, mechanical stability, and range of adjustment

need to be taken into account in selecting satisfactory combinations

of these variables.

(c) Some valves exhibited a sharp shutoff of the water flow at a condensing pressure close to the opening pressure and others required a pressure 10 psi or more below the opening pressure to stop the water flow.

The difference between the opening and closing pressures appeared to

be significantly greater for valves with a sliding valve port than

for the globe type valve element. A valve without a sharp shutoff

of water flow would have to be operated at a higher opening pressure,

or else it would permit some water leakage during the time the re- frigerating unit was not running.

(d) Six of the nine valve specimens revealed a gradual decrease in sensitivity factor as the maximum water flow rate was approached. This

characteristic suggests that it might be desirable to rate waterregulating valves on the basis of 90 percent maximum water flow rate,

since the operation conditions of a refrigerating unit at maximum

water flow rate would be considerably less efficient because of high

condensing pressures.

(e) The difference in refrigerant condensing pressure at 90 percent maximum water flow rate for increasing and decreasing values of condensing

pressure ranged from a negligibly small value for some valves to about

10 psi for the type with a sliding valve element. This hysteresis

effect could result in excessive water flow rates under fluctuating

load conditions or fluctuating condenser water temperatures.

(f) An increase in supply water pressure increased the sensitivity factor

of the valve specimens, and increased the decrement of refrigerant

condensing pressure below the opening pressure required to shut off

water flow, but it did not have a significant effect on the hysteresis of the valves in the operating range of water flow rate.

(g) Examples of water-regulating valves that exhibited chattering of the

moving element and overtravel of the moving element beyond the position of best port alignment were found among the test specimens. These

are illustrations of design factors that are of importance to the

proper functioning of water-regulating valves.

- 25 -

(h) The operating level of condensing pressure could be lowered for any

given cooling load by using an oversized water-regulating valve.

Table 11 shows the rise in refrigerant condensing pressure that

would be required to attain a 6 gpm flow rate through the 1/2-inch

valves and a 10 gpm flow rate through the 3/4-inch valves. The re- sults show that the valves manufactured by the Controls Company of

America and Penn Controls Inc. would operate with a pressure rise

of less than 25 psi. The pressure rises for the Marsh Instrument

Company valves are higher than the others, principally because the

pressure-flow curves flatten out significantly near the shutoff

condition, as shown in Figs. 11 and 12. However, it might be more

practical to redesign the spring and power elements to obtain a higher sensitivity factor for the valves and make fuller use of

the total flow capacity of the valves.

Table 11

Rise in Refrigerant Condensing Pressure Required

to Obtain Selected Water Flow Rates with Oversized Valves

Valve

Size

Required

Water Flow Rate

ingpm

1/2 6

3/4 10

Rise in Refrig. Condensing

Pressure to Attain Required

Water Flow Rate, psi

CC of A Marsh Penn

17 30 15

23 44 15

- 26 -

9 . 0 Recommendations for Specification Requirements

In the preparation of performance requirements and tests in future

Military standards and specifications, this investigation indicates that

the following factors should be considered:

1. Valve sizes should be based on desired water flow rate at rating

conditions with type and size of pipe connections a secondary con- sideration based on application.

2. The rating conditions should include:

(a) Valve opening pressure,

(b) Maximum rise in condensing pressure above opening pressure

to attain required water flow rate,

(c) Inlet water pressure and temperature,

(d) Pressure drop across the valve.

3. The water flow capacity of a valve should be based on 90 percent of

the maximum flow rate to avoid use of the zone of low sensitivity

likely to occur near the wide-open position of the valve.

4. Maximum hysteresis effect for increasing and decreasing refrigerant

pressures at rated water flow conditions should be specified. A

maximum value of 5 psi is probably reasonable.

5. Maximum difference between opening and closing pressures, at the rating conditions listed in item 2, should be specified. A maximum

value of 5 psi is probably reasonable for globe-type valves.

6. The range of conditions under which valve stability, and freedom from

chatter, resonance, and water hammer is required.

7. The required working range of water and refrigerant pressures should

be specified.

8. Safety requirements for strength and freedom from water leakage under

working and test pressures should be included.

9. Sampling and test procedures should be included or referenced.

10.

The requirements of the Military Standard should be referenced in the

specification, if they are applicable.

USCOMM-NBS-DC

- 27 -

Fig. 1. View of three Controls Company of

America water-regulating valves; the 1/2-inch

size is shown disassembled.

MARSH

Fig. 2. View of three Marsh Instrument Co.

water-regulating valves;, the 1/2-inch size

is shown disassembled.

Fig.

3.

View

of

three

Penn

Controls

Co.

water-regulating

valves;

the

1/2-inch

size

is

shown

disassembled
£ 7? 0
Fig.

4.

Diagram

of

apparatus

and

piping

used

for

tests

of

water

regulating

valves.
.
<uG

•Hc

o

4-1

•H > X r-4 G G

s >

LO

; 60

' -H

fa

PRESSURE

DROP

ACROSS

VALVE,

psi

COCl

LU>

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CO

COo

cro<

CLo

QCQ

LlI cc3

COCO

LlI cr

0-

<uc

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i-i o

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<13 Li3w

03

<13 Liaw3 • to 03

Li

N

<13 •H > 03

03 <u LI > m r—

Li cfl > &O

r—

£>

>4-1

X

Li <13 <13 a

4-1 3

tfl o

£f Li00 B3 03 B <13 >

t-H cO <0 S >

00 •H

p-l

WATER

FLOW

RATE,

gpm

REFRIGERANT CONDENSING PRESSURE, psig

Fig. 7. Water flow rate versus refrigerant condensing pressure

for 3/8- inch valve of Controls Company of America.

REFRIGERANT CONDENSING PRESSURE, psig

Water flow rate versus refrigerant condensing pressure

for 1/2-inch valve of Controls Company of America.

Fig. 8.

WATER

FLOW

RATE,

gpm

REFRIGERANT CONDENSING PRESSURE, psig

Fig. 9. Water flow rate versus refrigerant condensing pressure

for 3/4-inch valve of Controls Company of America.

WATER

FLOW

RATE,

gpm

REFRIGERANT CONDENSING PRESSURE, psig

Mg, 10c Water flow rate versus refrigerant condensing pressure

for 3/8-inch valve of Marsh Instrument Company

Fig. 11. Water flow rate versus refrigerant condensing pressure

for l/2=inch valve of Marsh Instrument Company

WATER

FLOW

RATE,

gpm

REFRIGERANT CONDENSING PRESSURE, psig

Fig. 12. Water flow rate versus refrigerant condensing pressure

for 3/4-inch valve of Marsh Instrument Company
i

.

:.*•y-M

!

-

>

'

•'4

-
WATER

FLOW

RATE

,

gpm

Fig. 13. Water flow rate versus refrigerant condensing pressure

for 3/8-xncfa valve of Penn Controls, Inc.

WATER

FLOW

RATE,

gpm

REFRIGERANT CONDENSING PRESSURE, psig

Fig. 14. Water flow rate versus refrigerant condensing pressure

for 1/2-inch valve of Penn Controls, Inc.

WATER

FLOW

RATE,

gpm

REFRIGERANT CONDENSING PRESSURE, psig

Fig. 15. Water flow rate versus refrigerant condensing pressure

for 3/4- inch valve of Penn Controls, Inc.