NATIONAL BUREAU OF STANDARDS REPORT

2134

MODEL 320-CQ ELECTRIC DRINKING WATER COOLER

manufactured by

Filtrine Manufacturing Company

by

Henry Karger

C, W. Phillips

P. R. Achenbach

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
U, S. DEPARTMENT OF COMMERCE

Charles Sawyer, Secretary

NATIONAL BUREAU OF STANDARDS

A. V. Astin, Director THE NATIONAL BUREAU OF STANDARDS

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of the activities, and of the resultant reports and publications, appears on the inside of the back

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NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT NBS REPORT

1003-40-4700 December 30 , 1952 2134

MODEL 320-CQ ELECTRIC DRINKING WATER COOLER

Manufactured by

Filtrine Manufacturing Company

by

Henry Larger

C. W. Phillips

P. R. Achenbach

Heating and Air Conditioning Section

Building Technology Division

to

Philadelphia Quartermaster Depot

U. S. Army

Philadelphia, Pennsylvania,

The publication, reprint

unless permission Is obt

25, D. C. Such permiss

cally prepared If that a

Approved for public release by the

Director of the National Institute of ‘‘*'‘^5' '''^^hington Standards and Technology (NIST)

'

t for Its own use on October 9, 2015.

Model 32 O-CQ Electric Drinking Water Cooler

by

Henry Karger

C. W. Phillips

P. R. Achenbach

Abstract

Performance tests were made of the cafeteria-type

electric drinking-water cooler, model 320-CQ, manufactured by Filtrine Manufacturing Company to determine compliance with Federal^. Specification 00-C-566b

with Amendment 2, as modified by Quartermaster Invitation to Bid QM II-OO9

- 52 -I 263 , amended, and by

Quartermaster Contract DA 11-009-QM-1S279 . Two

specimens were utilized for the tests because the

initial specimen melted the fusible plug in the receiver during the course of the tests and became inoperative. The second specimen met the requirements

of three of the performance tests and failed to meet

the requirements of four other perform.ance tests.

The test results indicated that insufficient cooling

was provided by the air-cooled condenser in the

machinery compartment which directly affected the

ability of the coolers to meet the requirements of

the Overload test and the Maximum Operating tests

and probably the Capacity and Peak Draw tests as well.

I. INTRODUCTION

In accordance with a request from the Chicago Quartermaster

Depot, Chicago, Illinois, in a letter dated July 15, 1952, performance tests were made of the cafeteria-type electric drinking

water cooler. Model 320-CQ, manufactured by Filtrine Manufacturing

Company, Brooklyn, New York, to determine compliance with Federal

Specification 00-C-566b, and Amendment 2 dated January 21, 1952,

as modified by exceptions noted in Invitation to Bid 11-009-

52 -I 263 dated March 26, 1952, Amendment ^1 dated April 21, 1952,

and contract DA ll-009-QM-1^279 dated May 13, 1952. Two specimens of this model water cooler were utilized in the tests. The

performance of the specimens was determined by direct tests as

required in the Federal Specification. Special tests described

herein were made to determine the performance of certain components. Analyses of m.aterials and inspection of construction

was not requested in the letter mentioned above; however, certain

construction features were noted during the performance tests and

some comments on these are included in this report.
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II. DESCRIPTION OF TEST SPECIMENS

The two water cooler specimens submitted for test were identified as follows:

NBS Test Specimen ^7-52, Specification Type III, Size 20

Filtrine Mfg Company Model 320-CQ

Identified in this report as specimen F-1

NBS Test Specimen 92-52, Specification Type III, Size 20

Filtrine Mfg Company Model 320-CQ

Identified in this report as specimen F-2

Specimen F-2 was submitted after Specimen F-1 developed a refrigerant leak and became inoperative because of loss of refrigerant during a performance test. Both specimens were of the cafeteria type

with two glass-fillers mounted on the upper part of the front side

on each. They were housed in formed steel enclosures which constituted the back and sides of the coolers. This housing enclosed

the condensing unit compartment and evaporator section and provided

structural support for the unit. The lower front panel could be

removed after loosening three screws and pulling out and up on it,

providing 'access to the condensing unit and all electric controls

and connections.

A front view of specimen F-1 is shown in Fig. 1, Fig, 2 shows

a rear view of the cooler, and the machine compartmient is shown in

Fig. 3. Fig. 4 shows a front view of the cooler specim.en F-2.

The dimensions and weight of the coolers were as follows:

Height, in.

Width of cabinet, in.

Depth of cabinet, in.

Depth of cooler including drain tray, in.

Weight, including wood shipping base, lbs.

26-1/4

17-1/2

25

359

The weight of the wooden shipping base was approximately 20 lbs.

Ill, TEST PROCEDURE

The laboratory investigation of the specimens were made to

determine compliance with the performance requirements of the

following paragraphs of the specification, some of which were modified in the Invitation to Bid or the contract:
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2) D-la, F-3d

3) D-lb, F-3b

4) D-lOd

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6) D-llb

7) D-lla, F-3c

Maximum Operatinp; Test

Refrigeration Control Test

Freezing Test

Motor Overload Protection Test

Overload Test

Capacity Test

Peak Draw Test

All performance tests listed above were conducted in a temperature-controlled room under steady-state conditions as set forth in

paragraph F-3a of the Federal Specification, except where the paragraph applicable for a specific test called for a different set of

conditions. Temperatures were measured by means of calibrated

thermocouples using an electronic, constant-balance type of potentiometer. Accuracy of this instrument was checked at intervals

during the test by means of ice-bath references. Inlet and outlet

drinking water temperatures were measured by thermocouples in thinwalled stainless steel wells four inches long, mounted so that the

thermocouple junctions were approximately in the plane of the exterior surface of the cooler cabinet. Supply water temperatures

and pressures were controlled by close-differential mechanical devices.

Additional information on the test procedure for particular

tests is included with the report of the test results to further

clarify how the results were obtained in cases where the specification did not provide adequate details.

The following paragraphs show the results obtained on specimens F-1 and F-2 during the performance tests listed under the

section on Test Procedure.

(1) Capacity Test (Paragraph D-1, E-3, F-3a)

Table 1, which follows, summarizes the results obtained during

the capacity tests on both specimen F-1 and F-2 and compares the observed performance with the specification requirements. The entry

entitled "Drinking Water Flow Rate at 30°F Temperature Difference,

Gallons per Hour" gives the calculated water flow rate for a 30°F

difference between supply and drinking water temperature when the

actual difference during the test was not exactly 30°F.

Table 1 shows that neither specimen F-1 nor specimen F-2 met

the capacity requirements for Type III, Size 20 coolers.

The automatic expansion valve adjustment was changed on specimen F-2 to raise the evaporator pressure and increase the cooler

the cooler capacity. It is believed that this accounts for the

greater capacity and higher current and power input shown in Table 1

for specimen F-2 than was observed for specimen F-1,

IV. TEST RESULTS
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TABLE 1. CAPACITY TESTS OF SPECIMENS F-1 AND F-2.

Performance

Characteristics

Required

Performance

Observed

Performance

Specimen Specimen

F-1 F-2

Ambient Temperature, ®F

Electric Power Input, watts

Terminal Voltage

Total Current Input, amps

Drinking Water, Inlet Temp., °F

Drinking Water, Outlet Temp., °F

Drinking Water, Temp. Diff., °F

Drinking Water ^ flow rate,

observed, gph

Drinking Water flow rate, correct

for a 30°F temp, diff., gph

90 90.5

- 796 1007

115 115 115

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50 50.6 50.1

30 30.3 29.9

- 13.6 16.5

1^.0 13.7 16.4

minimum)

(2) Peak Draw Test (Paragraph D-la modified, F-3d)

Paragraph D'-la of the specification, as modified by exception

in the contract, specified that 65 percent of the required hourly

capacity shall be drawn off in 15 minutes during the peak draw

test, ilie water temperature at the beginning 'of the 15-minute

period must be neither lower than 45°F nor higher than 50°F and

the temperature rise shall not exceed 10 degrees at any time during

the 15-minute period. The water must be drawn off, beginning immiediately after the compressor-motor cuts off in a normal cycle,

in not less than three nor more than six equal intervals per gallon

of required draw-off capacity. The water must be drawn off at a

rate of not less than 1/2 gallon per minute per glass filler.

The peak draw test was made with cooler specimen F-2. The required amount of water, 11.7 gallons, was withdrawn through the

glass fillers in 54 equal samples, with an initial outlet water

temperature of 49«2°F. The highest subsequent outlet water temperature observed during the 15-minute period was 59.9°F. This rise

in temperature of 10.7°F exceeded the permissible rise of 10 degrees,

hence cooler specimen F-2 did not comply with this requirement

of the specification.

(3) Maximum Operating Test (Paragraphs D-lb, F-3b)

The specification required that the cooler should operate

satisfactorily for at least ^ hours under conditions of 110°F

ambient temperature, 100°F inlet water temperature, and 50°F

outlet water temperature and should start satisfactorily under

these same conditions.

5 -

Both cooler specimens were subjected to these test conditions. Specimen F-1, after being operated for 6-1/2 hours under

the above conditions developed a leak in the refrigerant system

and lost its charge of refrigerant. Investigation revealed that

the fusible plug in the receiver outlet fitting had melted. Fig.

shows this fitting after it had been repaired bv representatives

of the manufacturer. By mutual agreement between manufacturer and

the purchaser a second specimen v/as submitted for test, rather than

continue the tests on the repaired cooler.

An attempt was made to run the Maximum Operating Test v/ith

cooler specimen F-2. This test could not be completed because

the m.otor overload 'protective device disconnected the compressor

motor from the circuit before steady state conditions had been

reached. Just prior to the time of cutout, the following conditions were noted:

Subsequently the front panel was removed from, the cooler, and it

was then able to operate without causing the overload protector

to function. The failure of the fusible plug in specimen F-1,

and the excessive discharge pressure observed with specimen F-2,

showed that the design of the air circuit for cooling the condenser

and machinery compartment needed improvement. These observations

show’- that neither of the test specim.ens complied with the requirem.ents of the Maximum Operating Test.

(4) Refrigeration Control Test (Paragraph D-lOd)

The Refrigeration Control Test v/as made with cooler specimen

F-2. The cooler was equipped wdth a thermostat which controlled

the operation of the compressor motor. The thermostat was readilv

accessible for adjustment and servicing w/hen the front panel of

the cooler w^as removed; however, it could not be replaced without

remoA’-ing the top of the cooler cabinet and part of the insulation

in. the cooling unit housing.

Adjustment of the thermostat could be effected by turning a

knob, w/hich had a dial divided into seveh positions, numbered from

1 to 7. An arrow on the dial indicated that the thermostat would

cause the cooler to deliver colder water w^hen the knob was turned

to the higher numbers on the dial, i.e. position number 1 would

be the warmest position and position number 7 would be the coldest

position

The specification requirement, as m.odified in Amendment 2,

stated in part:

Discharge Pressure, psig

Motor Case Temperature,

Current, amps

301

202

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"Unless otherwise specified, the temperature control

of the water shall be adjustable between 45°F and

55°F« and shall have a differential of not more than

plus or minus 5°*”

This requirement was interpreted by this Bureau to mean that a

thermostat would be in compliance if at some condition of flow

it would produce water at a control point temperature of 45°F

at some setting of the knob, and at a control point temperature

of 55°F at some otheir setting of the knob, with a differential

not to exceed plus or minus five degrees. In accordance with

previous tests made at the Bureau for water coolers purchased

under the same specification requirement, the rate of water withdrawal for this test was set at 1/2 of the required hourly capacity

of the cooler, or approximately 9 gallons per hour.

Two 9-fl»oz. samples of water were withdrawn from the cooler

every two minutes through one of the glass fillers for the duration

of the thermostat test. The first of these samples was discarded

into the drain of the cooler, and the temperature of the second

sample was recorded. The test was thus continued for one hour,

which was sufficient time to cause several therm^ostat cycles to

occur for the highest setting of the thermostat and to indicate

steady outlet water temperatures for the lowest setting of the

thermostat. The test was conducted in an ambient temperature of

90°F and the inlet water temperature to the cooler was maintained

at ^0°F.

Under the above conditions, the average of the water temperatures observed at the highest setting of the thermostat was 57.2°F,

and the maximum observed deviation from this average was 0,4°F. At

the lowest setting of the thermostat, the average of the water

temperatures observed was 44.0°F, and the maximum deviation from

the average was 0,7®F. This test indicated compliance with the requirement of the specification.

(5) Freezing Test (Paragraph D-lOd(l))

Each cooler specimen had an additional thermostat to serve as

a protective device against freezing. The freezing tests were made

with cooler specimen F-2. Three tests were made, the first in an

ambient temperature of 50°F, the other tv7o in an ambient temperature of 35°F. Each of the three tests was continued for 4^ hours.

The primary drinking-water thermostat was shunted, and the cooler

was operated under the above conditions. No freeze-ups occurred

during any of the three tests, and drinking water could be drai-m

from the cooler at the conclusion of each test.
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(6) Motor Overload Protection Test (Paragraph D-llb)

Paragraph D-llb states in part: ’’Motors shall be protected in case of failure of the starting mechanism or excessive

overload by a thermal protective device of proper current rating, which shall open the circuit before the motor windings

reach a temperature that will injure the motor,”

Each cooler specimen was equipped with such a device.

Tests were made with specimen F-2. To determine the protection afforded, two tests were made, both in a 90°F amibient temperature, with supply water flowing steadily through the cooler at

a rate slightly in excess of 60 gallons per hour. First , the

power lead to the starting winding of the motor was disconnected.

The cooler was then energized electrically, and measurements were

made of the motor running winding resistance immediately following each cutout of the overload protector. The overload protector was allowed to function until successive resistance measurements observed at the time of cutout ivere no longer increasing,

and the temperature rise of the winding was computed on the basis

of the highest resistance observed. The highest miotor winding

temperature indicated under these conditions was 204°F. Second , the condenser fan was disconnected, the air flow over the condenser was blocked, and the cooler was allowed to continue in

operation. Using the method described above, the highest motor

winding temperature computed, based on resistance measurements,

under these conditions was 201°F.

Based on present accepted practice in the design of herm.etic

m.otor-com.pressor units, it is the opinion of this Bureau that the

com.pressor miOtor of this cooler was adequatel^r protected against

overload and against excessive temiperatures caiised by motor overload .

(7) Overload Test (Paragraph F-3c, D-lla miodified)

Both cooler specimens x*/ere tested in accordance with the requirem.ents of paragraph F-3c of the specification, which called

for 4 hours of continuous operation in 100°F ambient temperature

wdth water dra-vm at the rate of 300 percent of the required hourly capacitor. The inlet water temperature was held at approximately B0'°F.

Cooler specimen F-1 operated satisfactorily and without any

indication of breakdown. The tem.perature rise of the motor running

winding was determined by the resistance method and computed by

the formula given in paragraph 4.2,3 of Federal Specification

CC-M-636a, dated October 29, 1951. The results of the test m.ade

with specimen F-1 are sum.marized in Table 2, which follows.

Table 2 shows that the temperature rise of the motor v/indings
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was below the permissible rise for totally enclosed motors in

this specification. It is pointed out that Federal Specification CC-M-636a does not carry any reference to motors of hermetically-sealed motor-compressor units. It is believed, however, that the coil-winding temperature-rise limit for totallyenclosed type motors in this specification should serve as a

p-uide in judging hermetic motors.

TABLE 2. OVERLOAD TEST OF SPECIMEN F-1

Performance

Characteristics

Required

Performance

Observed

Performance

Ambient Temperature, °F

Drinking Water Inlet Temp., °F

Drinking Water Outlet Temp., °F

Ratio of Drinking Water Flow to

Required Capacity, %

Electric Power Input, watts

Terminal Voltage

Temperature Rise of Motor

Windings, ®C

100 99.7

— go.o

- 72.9

300 303

— ^00

115 115

65-

(maximum)

54.4

Permissible temperature rise for totally-enclosed fractionalhorsepower motors in Federal Specification CC-M-636a.

An attempt was made to run the Overload Test with cooler

specimen F-2. As in the case of the Maximum Operating Test, the

Overload Test could not be made because the motor overload protective device disconnected the compressor motor from the circuit before steady state conditions had been reached. The operating conditions observed just prior to cutout of the protective

device and the temperature rise of the running windings just

after cutout were as follows:

Discharge Pressure, psig 320

'i^Motor Case Temperature, °F 199®

Current, amps 12.5

Motor Winding Temperature Rise,°C 65

Under the protective device

The front panel was then removed from the cooler, after which

the motor was able to operate without exceeding the temperature

setting of the overload protective device. As already pointed

out in section 3 under Maximum Operating Test, the results indicate that the design of the air circuit of the cooler needed

improvement to reduce the discharge pressure and the load on

the compressor motor.

- 9

-

The change in expansion valve setting made on specimen F-2 to

increase the water-cooling capacity of the specimen during the

capacity test caused higher power consumption of the compressor

meter and greater temperature rise of this specimen than for specimen F-1 during the Overload test. The change in expansion valve

setting undoubtedly was the reason why specimen F-2 failed to meet

the Overload test requirements whereas specimen F-1 did meet them.

However, the coolers should probably be judged on the basis of performance of specimen F-2 because the expansion valve adjustment was

necessary to increase the capacity of the coolers. It should be

noted that even with the expansion valve adjustment used on specimen F-2, it did not meet the requirements of the capacity test.

(S) Housing and Insulation (Paragraph D-9d modified)

Although inspection of the cooler construction was not requested by the Chicago Quartermaster Depot some deficiency was observed

in the vapor sealing of the cooling unit housing while making the

performance tests. It was noted that the vapor seal of the cooling

unit housing of neither cooler specimen -met the requirements of

paragraph D-9d of the specification. This paragraph required that

the entire cooling unit housing should be sealed against infiltration of moisture. The vapor seal on each of the two coolers covered

about three-fourths of the cooling unit housing. Part of the storage

tank was exposed to the ambient air and moisture collected on the

tank surfaces when they were below the dew point of the ambient air.

V. CONCLUSIONS

The performance tests of the two cooler specimens indicated

important deficiencies in both units. The observed capacity of

specimen F-1 was only ?6 percent of that required by the specification

and this specimen melted the fusible plug ip its receiver during

the Maximum Operating test.

The capacity of specimen F-2 was 91 percent of that required

by the specification and it failed to pass three other tests out of

a total of seven performance tests. This specimen complied with

the specification requirements of the Refrigeration Control test,

the Freezing test, and the Motor Overload Protection test but failed

on the following four requirements:

1. Capacity Test

2. Maximum Operating Test

3. Overload Test

4. Peak Draw Test
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The discharge pressures observed during the Maximum Operating

Test and the Overload Test indicated insufficient cooling was being

provided by the air-cooled condenser within the machinery compartment, The performance of the specimens during the Capacity Test and

the Peak Draw Test was probably affected adversely by the deficiency

in the air-cooling circuit.

In view of the failure of the cooler specimens to meet several

of the major specification requirements, it is recommended that the

coolers not be purchased by the Government unless satisfactory design changes are made.

FIG 1

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»

V
THE NATIONAL BUREAU OF STANDARDS

Functions and Activities

The functions of the National Bureau of Standards are set forth in the Act

of Congress, March 3, 1901, as amended hy Congress in Public Law 619, 1950.

These include the development and maintenance of the national standards of

measurement and the provision of means and methods for making measurements

consistent with these standards; the determination of physical constants and

properties of materials; the development of methods and instruments for testing

materials, devices, and structures; advisory services to Government Agencies on

scientific and technical problems; invention and development of devices to serve

special needs of the Government; and the development of standard practices,

codes, and specifications. The work includes basic and applied research, development, engineering, instrumentation, testing, evaluation, calibration services

and various consultation and information services. A major portion of the

Bureau’s work is performed for other Government Agencies, particularly the

Department of Defense and the Atomic Energy Commission. The scope of activities is suggested by the listing of divisions and sections on the inside of the

front cover. Reports and Publications

The results of the Bureau’s work take the form of either actual equipment and

devices or published papers and reports. Reports are issued to the sponsoring

agency of a particular project or program. Published papers appear either in the

Bureau’s own series of publications or in the journals of professional and scientific

societies. The Bureau itself publishes three monthly periodicals, available from

the Government Printing Office: The Journal of Research, which presents complete papers reporting teclmical investigations; the Technical News Bulletin, which

presents summary and preliminary reports on work in progress; and Basic Radio

Propagation Predictions, which provides data for determining the best frequencies

to use for radio communications throughout the world. There are also five series

of nonperiodical publications: The Applied Mathematics Series, Circulars, Handbooks, Building Materials and Structures Reports, and Miscellaneous Publications.

Information on the Bureau’s publications can be foimd in NBS Circular 460,

Publications of the National Bureau of Standards ($1.00). Information on cali- bration services and fees can be found in NBS Circular 483, Testing by the National

Bureau of Standards (25 cents). Both are available from the Government Prmting Office. Inquiries regarding the Bureau’s reports and publications should be

addressed to the Office of Scientific Publications, National Biureau of Standards,

Washington 25, D. C.
oI

03

‘93