NATIONAL BUREAU OF STANDARDS REPORT

2559

PERFORMANCE OF TWO ELECTRIC

DRINKING WATER COOLERS

manufactured by

Sunroc Company

by

C. W. Phillips

Henry Karger

P. R. Achenbach

<NBS>

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
U. S. DEPARTMENT OF COMMERCE

Sinclair Weeks, Secretary

NATIONAL BUREAU OF STANDARDS

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

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Cr-iOOXH

NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT NBS REPORT

1000-30-4700 June 15, 1953 2559

PERFORMANCE OF WO ELECTRIC

DRINKING WATER COOLERS

manufactured by

Sunroc Company

by

C. W. Phillips

Henry Karger

P. R. Achenbach

Heating and Air Conditioning Section

Building Technology Division

to

Headquarters

,

United States Marine Corps

Washington, D* C.

The publication, reprln

unless permission is obt

25, D, C, Such permls

cal ly prepared If that

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST)

on October 9, 2015.

tart. Is prohibited

lards, Washington

t has been specifirt for Its own use.

PERFORMANCE OF TWO ELECTRIC

DRINKING WATER COOLERS

ABSTRACT

Two electric drinking water coolers were tested for

the United States Marine Corps to determine their

compliance with the purchase specification and its

addenda issued with U. S. Marine Corps Invitation

for Bids #$32. Both specimens failed to meet certain performance requirements and were returned to

the manufacturer for modifications. After resubmission

of the specimens, all of the tests were repeated on

one of the coolers, and certain of the tests were repeated on the other cooler. Inspections and material

analyses were made of both coolers. The results obtained show that one cooler essentially met all the

performance requirements and all but two of the construction requirements of the purchase specification.

The second cooler met all the performance requirements with the exception of the Peak Draw Test, the

Water Regulator Test, and the Overload Test. It met

the majority of the construction requirements of the

purchase specification.

I. INTRODUCTION

In accordance with a request from the Headquarters, United

States Marine Corps, in a letter dated May 26, 1952, tests and

inspections of two electric drinking water coolers of different

models manufactured by Sunroc Refrigeration Company, Glen Riddle,

Pennsylvania, were made to determine compliance with the purchase specification and its addenda attached to the U. S. Marine

Corps Invitation for Bids #$32, dated February 29, 1952, and

contract NOM-62695, dated May 1, 1952, issued by Headquarters,

United States Marine Corps. One cooler of each of the two models

was submitted by the manufacturer for tests. Both coolers were

returned to the manufacturer when it became apparent during the

tests that they did not comply with certain of the specification

requirements, and were subsequently resubmitted by the manufacturer

after certain modifications were made.

The performance of the two specimens was determined by direct

tests as required by the purchase specification and its addenda.

Conclusions about compliance of the specimens with regard to

materials, construction, and durability were drawn from the results

of inspections, plating tests, and other physical and chemical determinations. The tests required such detailed dismantling and

sampling of construction materials of both coolers that it was

impracticable to attempt reassembly.

2

II. DESCRIPTION OF TEST SPECIMENS

Thw two water cooler specimens submitted for tests were

identified as follows:

NBS Test Specimen $3-52, Specification Tyne I, Size 10

NBS Test Specimen 97-52 (when resubmitted)

Sunroc Company Model NM2B

Serial Number 220117

Code Number MOD 1-10AH1

Identified in this report as specimen S-10

NBS Test Specimen $9-52, Specification Type III, Size 30

NBS Test Specimen 99-52 (when resubmitted)

Sunroc Company Model A-2520

Serial Number 220306

Code Number 3-30AH1

Identified in this report as specimen S-30

Specimen S-10 was housed in a formed, one-piece steel enclosure

which constituted the back and the sides of the cooler. This

housing enclosed the condensing unit compartment and evaporator

section and provided structural support for the unit. The solid

front panel could be removed, after loosening a screw at the

bottom of the panel, by pulling the panel away from the cooler

at the bottom and down from the recess formed by the top of the

cooler. All of the controls and electric connections were accessible from the front side after the front panel was removed.

A front view of the specimen S-10 is shown in Fig. 1.

Fig. 2 shows a rear view of the cooler, and the machine compartment is shown in Fig. 3 after removal of the front panel.

Specimen S-30 was housed in a formed, sheet steel enclosure

which completely enclosed the cooling unit housing and also constituted the sides of the machine compartment. The condenser

occupied all of the back side of the machine compartment. The

sheet-steel-mesh front cover of the machine compartment could be

removed after loosening four screws, and all electric controls

were accessible from the front of the machine compartment. The

cooler was supported on four adjustable steel legs.

A front view of specimen S-30 is shown in Fig. 4. Fig. 5

shows a rear view of the cooler, and the machine compartment is

shown in Fig. 6. When the cooler was returned for modification

after it failed to comply with certain requirements of the purchase specification, the manufacturer removed the receiver and

the automatic expansion valve, and a capillary tube was substituted as the refrigerant flow control. The machine compartment of specimen S-30 after this modification is shown in Fig. 7

as follows:

- 3 -

The dimensions of the two coolers were

S-10 S-30

Height, in. 41-1/2 55

Width, in. 15-1/2 25 - 1/2

Depth of cabinet, in. 15-1/2 25 - 1/4

Depth of cooler (incl. draintray) , in. 15-1/2 33 - 1/2

Weight, lbs. (approx.) 140 350

III. TEST PROCEDURE

The laboratory investigation of the specimens made to determine compliance with the purchase specification and the

three addenda attached thereto was divided into two main parts.

First, tests were made to determine compliance with the performance requirements of the specification, as follows:

Specification

Paragraph No. Tvne of Test

(1) E-l, F-3c Capacity Test

(2) E-2

,

F-3f Peak Draw Test

(3) E-3, F-3d Maximum Operating Test

( 4 ) E-4, F-3e Overload Test

(5) E-5, F-3g Automatic Temperature Control Test

(6) E-6, F-3h Motor Overload Protective Device Test

(7) E-7, F-3 j Water Regulator Test

(3) E-g, F-3i Freezing Test

(9) F-3a , F-3k Hydrostatic Test

Secondly, tests and/or inspections were made to determine

compliance with other applicable paragraphs relative to materials

of construction, composition of materials, arrangement of components, etc.

All performance tests listed above were conducted in a temperature-controlled room under the general conditions set forth

in paragraph F-3b of the purchase specification. 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 tests by

means of ice-bath references. Inlet and outlet drinking-water

temperatures were measured by thermocouples in thin-walled, stainless steel wells four inches long, mounted so that the thermocouples junctions were approximately in the plane of the exterior

surface of the cooler cabinet. Water-flow rates were determined

in a manner that did not interfere with the flow of cooled water

wasted through the precooler. Supply water temperatures and

pressures were controlled by close-differential mechanical

devices

- 4

-

IV. PERFORMANCE TEST RESULTS

When specimen S-10 was placed on the testing stand and connected to the water supply, it was found that the bubbler would

not pass more than a trickle of water when opened. Inspection

disclosed that some foreign material had lodged on the screen of

the bubbler, as shown in Fig. £. The bubbler was replaced by the

manufacturer before the tests began. With the exception of the

water regulator test and the automatic temperature control test,

all test results reported herein on specimen S-10 were obtained

on the original sample as first submitted. The water regulator

test and the automatic temperature control test were repeated on

specimen S-10 after it was resubmitted and the results reported

are those obtained on the resubmitted specimen.

The specimen S-30 developed a refrigerant leak after six of

the nine tests outlined in the section under Test Procedure were

finished. The cooler had met the requirements of the capacity

test, the maximum operating test, and the automatic temperature

control test, however failed to meet the requirements of the peak

draw test, the water regulator and valve test, and the motor overload protective tests. During the test of the Motor Overload

Protective device, this device failed to operate after several

cycles. In order to prevent a burnout of the compressor motor,

it was disconnected manually. The temperature of the running

winding of the compressor motor at that time was 521°F. The

temperature of the winding at the last cutout of the protective

element before its failure was 421°F. The specification requires

that the protective elements function before winding temperatures

exceed 257°F. The failure occurred during the test made with the

starting winding of the compressor motor disconnected to simulate

failure of the starting mechanism.

The day after the above test was made a refrigerant leak was

discovered at the place where the suction line entered the hermetic compressor shell. The cause of this leak was not determined.

The cooler was returned to the manufacturer, and all tests

were repeated on the resubmitted sample. These are the test results enumerated below.

The following paragraphs show the results obtained on specimens S-10 and S-30 during the performance tests listed under the

section on Test Procedure.

(1) Capacity Test (Paragraphs E-l, F-3c)

Table 1, which follows, summarizes the results obtained during

the capacity tests on specimen S-10 and specimen S-30 and compares

the observed performance with the specification requirements

- 5 -

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 outlet water temperature when the actual difference during the test was not exactly

30°F.

Table 1 shows that the observed capacity of both cooler specimens exceeded the respective required capacity,,

TABLE 1. CAPACITY TESTS OF SPECIMENS S-10 AND S-30

Required Observed

Performance Characteristic Performance Performance

Ambient Temperature, °F 90

S-10

90.3

S -30

89.9

Electric Power Input, watts - - 1234

Terminal Voltage 115 115 115

Total Current, amps - 3.S 14.6

Drinking Water, Inlet Temp., °F £0 SO.

79.6

Drinking Water, Outlet Temp. , °F 50 50.0 49.7

Drinking Water, Temp. Diff .

,

°F 30 30.6 29.9

Spill through precooler for o

i

—

i

cn 60 59.8 -- Drinking Water Flow rate, observed,

gal. /hr.

Drinking Water Flow rate, corrected

for a 30°F temp. diff., gph,

11. g 30.

g

for specimen S-10

Drinking Water Flow rate, corrected

for a 30°F temp. diff. , gph,

9.5

(minimum)

12.0

for specimen S-30

(2) Peak Draw Test (Paragraphs

2g. 5

( minimum)

E-2 , F-3f)

30.7

For the cooler type and size of specimen S-10, the specification required that 37-1/2$ of the required hourly capacity shall

be drawn off in 15 minutes. The water must be drawn off in either

30 or 60 equal intervals, at a flow rate of l/2 gallon per minute,

and with 60$ spill through the precooler. During the peak draw

test, the outlet drinking water temperature should not exceed 60°F

at any time. For this test, cooler specimen S-10 was equipped with

a self-closing, hand-operated valve adjusted to permit water to

flow at a rate of l/2 gallon per minute when opened. Water was

drawn from the cooler in 60 equal samples, each consisting of a

40$ portion, drawn first, and a 60$ portion , drawn second. The 40$

- 6 -

portion was poured into a container for subsequent weighing.

It simulated water consumed and did not pass through the precooler. The 60% portion was poured into a vessel of low thermal

mass immediately prior to each subsequent draw. This vessel

allowed the 60jo portion to flow through the precooler during

the time required for the entire subsequent draw.

During the peak draw test made with cooler specimen S-10,

the highest outlet drinking water temperature observed was

55. $°F, hence the cooler complied with the requirements of the

specification

For the cooler type and size of specimen S-30, the specification required that 6 5% of the required hourly capacity be

drawn off in 15 minutes. The water must be drawn off in either

30 or 60 equal intervals, at a flow rate of 4-1/2 gallons per

minute for the case of specimen S-30. During the peak draw test,

the outlet drinking water temperature should not exceed 55°F

at any time.

The peak draw test was made in accordance with the procedure

outlined in paragraph F-3f of the purchase specification. The

highest outlet drinking water temperature observed during the

test was 55.5°F after all tolerances in instrument and observation error had been resolved in favor of the test specimen.

During another peak draw test, in which the amount of water withdrawn was limited to prevent the outlet water temperature from

rising above 55«0°F, only 17.5 gallons instead of the required

1$. 5 gallons of water were withdrawn from the cooler, or approximately 5% less than required. This is the equivalent of 15 $-fl,

oz. glasses of water. The required 13.5 gallons to be drawn during the peak draw test are equivalent to 296 $-fl. oz. glasses

of water. The results of this second test corroborated the results of the first test. Inasmuch as the observed outlet water

temperature during the prescribed peak draw test rose above 55.0°F,

the specimen did not meet the requirements of the peak draw test.

(3) Maximum Operating Test (Paragraphs E-3 , F-3d)

The specification required that the coolers should start and

operate sat isfactorilv under conditions of 110°F ambient temperature, 100°F inlet water temperature, 50°F outlet water temperature,

with 60% spill through the precooler in the case of specimen S-10

and with no spill through the precooler in the case of specimen

S-30. The coolers should be operated continuously for at least

4 hours with the inlet water pressure at 20 psig, and for another

4 hours with the inlet water pressure at 75 psig.

- 7

-

Both cooler specimens were operated for the required length

of time under the above conditions. At the conclusion of each

of the 4-hour test periods, the coolers were turned off and left

idle for a period of 5 minutes and then restarted to determine

whether or not they would start satisfactorily without causing

the motor overload mechanism to operate. Both cooler specimens

started and operated satisfactorily during this test.

Table 2, which follows, shows the average conditions maintained during the maximum operating tests.

TABLE 2. MAXIMUM OPERATING TESTS

Required Observed

Performance Characteristics Performance Performance

Inlet Water Pressure

20 P.sig 75 psig

SPECIMEN S- 10

Electric Power Input, watts «=> 325 327

Terminal Voltage 115 115 112

Total Current, amps - 3.9 4.0

Ambient Temp. , °F 110 110.5 110.5

Drinking Water Inlet Temp., °F 100 99.2 100.4

Drinking Water Outlet Temp., °F 50 49.9 50.1

Drinking Water, Temp.Diff., °F 50 49.3 50.3

Spill through precooler, % 60 60.3 60.2

Drinking Water Flow Rate,

observed, gal/hr — 6.2 6.2

Drinking Water Flow Rate, Corrected

for 50°F temp, diff . , gph - 6.1 6.2

SPECIMEN S -30

Electric Power Input, watts 1437 1434

Terminal Voltage 115 115 115

Total Current , amps — 15.9 15.9

Ambient Temp., °F 110 110.9 110.7

Drinking Water Inlet Temp., °F 100 99.8 99.8

Drinking Water Outlet Temp., °F 50 50.7 50.3

Drinking Water, Temp. Diff., °F 50 49.1 49.5

Drinking Water Flow Rate,

observed, gal/hr - 15.7 15.1

Drinking Water Flow Rate, corrected

for 50°F temp. diff. , gph - 15.4 14.9

(4) Overload Test (Paragraphs E-4, F-3e)

Both cooler specimens were tested in accordance with the

procedure outlined in paragraph F-3e of the purchase specification, which calls for 4 hours continuous operation in 104°F

ambient with water withdrawn at a rate of 300% of the required

hourly draw-off capacity, and with 60% spill through the precooler in the case of specimen S-10. The results of these

tests are summarized in Table 3, which follows.

TABLE 3. OVERLOAD TEST

Performance Characteristics

Required

Performance

Observed

Performance

S-10 S-30

Ambient Temp. , °F 104 103.6 104.7

Drinking Water, Inlet Temp.,

Drinking Water, Outlet Temp.,

Ratio of Water Flow to flow

°F 90 39 .$ 39.9

°F — 75.0 74.0

required for capacity test,

Spill through precooler, %

$ 300 301 302

(Specimen S-10 only) 60 60.1 - Electric Power Input, watts - 337 1630

Terminal Voltage

Temp, rise of fan motor

115 115 115

frame, °F

Temp, rise of compressor

99

(maximum)

33.9 39.2

motor windings, °F 117

( maximum)

104.0 126.0

Both cooler specimens operated satisfactorily and without

any indication of breakdown. The temperature of the compressor

motor running windings was determined by the resistance method.

Table 5 shows that the temperature rise of the compressor motor

of specimen S-10 was below the permissible rise as listed in the

specification.

In the preliminary letter report to the Marine Corps dated

December 3, 1952, specimen S-30, as resubmitted, was reported as

passing the requirements of the Overload Test. However, a final

check of all data revealed that the temperature rise of the compressor motor winding was 9°F greater than the allowable maximum

rise of 117°F. Hence specimen S-30 did not pass the requirements of the Overload Test.

- 9

-

(5) Automatic Temperature Control Test (Paragraph E-5,

F-3g, as modified in Addendum #2 ) Both cooler specimens were equipped with thermostats,

actuated by refrigerant and/or water temperatures, which controlled the operation of the compressor motors. The thermostats were readily accessible for adjustment and servicing

when the front covers of the coolers were removed, and could

be replaced without breaking the main insulation of the cooling unit housing.

Adjustment of the thermostat on specimen S-10 could be

effected by turning a knob on the thermostat. The thermostat caused the cooler to deliver colder water when this knob

was turned in a clockwise direction, and caused delivery of

warmer water if the knob was turned in a counterclockwise

direction

Adjustment of the thermostat on specimen S-30 could be

effected by turning a screw located on the face of the thermostat. The thermostat caused the cooler to deliver colder water

when this screw was turned in a clockwise direction, and caused

delivery of warmer water when the screw was turned in a counterclockwise direction.

Specimen S-10, as delivered, did not meet the requirements

of the automatic temperature control test. For the case of

specimen S-10, the specification states in part:

TT

. . . . the automatic temperature control shall provide

drinking water at temperatures no lower than A OF. and no

higher than 50 F. for some one position of the thermostat adjusting device, and shall provide drinking water

at temperatures no lower than 50 F. and no higher than

60 F. for some other position of the thermostat adjusting device for any rate of water withdrawal from no-load

to one-half the . . . hourly capacity . . . , when the

coolers are operated in accordance with the conditions

of Paragraph F-3g. ,r

A knob setting was provided causing water delivery in the temperature range from 40°F to 50°F for both T, no-load Tt and TT half-load TT withdrawal rates. However, water at temperatures between 50°F

and 60°F could not be obtained for any setting of the adjustable

knob.

10

Specimen S-10 was returned to the manufacturer and was resubmitted at the same time that specimen S-30 was resubmitted.

The thermostat test was repeated, and after some internal adjustments of the thermostat by representatives of the manufacturer,

the cooler met the requirements of the thermostat test. At the

low setting of the thermostat adjusting knob, delivered water

temperatures ranged from 43*0°F to 45.1°F at "half-load" rate,

and from 44.7°F to 46.7°F at "no-load" rate. At the high setting

of the thermostat adjusting knob, delivered water temperatures

ranged from 52.2°F to 54.5°F at "half-load" rate and from 52.0°F

to 5 3.5°F at "no-load" rate. Inasmuch as some internal adjustment of the thermostat was necessary after deliverv of the cooler

to this Bureau the thermostat was removed from the cooler and calibrated in a bath in order to provide information for inspection

purposes. It was found that at the lowest setting of the thermostat adjusting knob, the cut-off was 45°F and the cut-on was 51°F,

and at the highest setting of the knob, the cut-off was 53°F and

the cut -on was 56 °F.

For the case of specimen S-30, the thermostat requirement

was similar to the requirement quoted above, except that the

low setting temperature limits were 37°F to 44°F instead of

40°F to 50°F, and the high setting temperature limits were

44°F to 50°F instead of 50°F to 60°F. For the low setting of the

thermostat adjusting screw, delivered water temperatures ranged

from 40„0°F to 40.3°F for the "half-load" rate, and from 40.6 to

42.4 for the "no-load” rate. For the high setting of the thermostat adjusting sc_rpw, the delivered water temperatures ranged from

45.2°F to 49.4°F for the "half-load" rate and from 4$.2°F to 50.0°F

for the "no-load" rate. Hence specimen S-30 met the requirements

of the automatic temperature control test.

Water at a temperature below 37°F could not be obtained from

either of the cooler specimens at the lowest possible settings of

the normal thermostat adjusting devices.

(6) Motor Overload Protective Device Test (Paragraph E-6, F-3h)

Paragraph D-13b of the purchase specification states in part:

"Compressor motors shall be protected in case of failure of the

starting mechanism, failure of the condensing medium, or excessive

overload, by a thermal protective device of the automatic or handreset type."

Both specimen S-10 and specimen S-30 were equipped with such

devices. Specimen S-10 had a single, automatic reset type overload protector, whereas specimen S-30 had two overload protectors,

one an automatic reset type, the second a hand-reset type, which

was connected in series with the first device.

11

Tests were made in accordance with the procedure outlined

in paragraph F-3h. Winding temperatures were determined by the

resistance method, using the formula in paragraph F-3h(4) to

compute the temperature. The results obtained during the tests

are listed in Table 4, below.

TABLE 4. MOTOR OVERLOAD PROTECTIVE TESTS

Temperature of

Windings, °F

Specification

Requirement

Observed

Performance

Maximum

Permissible

Temperature

S-10 S-30

Blocked Condenser 257 133 230

Starting Winding

disconnected 257 204 250

Condenser fan motor,

locked rotor test 257 297 222

The fan motor on specimen S-10, which reached a winding

temperature of 297°F during the locked rotor test, did not have

any overload protector, whereas the fan motor of specimen S-30

did have an internal overload protective device. The Technical

Committee on Refrigeration and Air Conditioning Equipment of

the General Services Administration, which is currently working

on a revision of the Federal Specification for water coolers, at

a recent meeting changed the temperature limits on electric motors

from 257°F to 302°F after reviewing all available information from

manufacturers of small motors and various regulatory groups.

Hence, we believe that the temperature of 297°F, attained by the - fan motor on this cooler, should be considered acceptable.

On specimen S-30, which was equipped with two overload protectors as outlined above, the automatic reset type protector

disconnected the compressor motor during the test made with the

condenser blocked. During the test made with the starting winding disconnected, the hand-reset type protector disconnected the

compressor motor.

(7) Water Regulator Test (Paragraph E-7, F— 3 j

)

The water regulator requirement states in effect that when

the unit is adjusted so that the observed water flow is onehalf gallon per minute for the case of specimen S-10, or 4-1/2

gallons per minute for the case of specimen S-30, at a supply

line pressure of 35 psig, the total flow at either 20 psig and

12

75 psig, respectively, shall not vary by more than 15% from the

total flow observed at 35 psig.

Specimen S-10 was equipped with an adjustable, automatic

water-pressure regulator and a hand-operated, push-button type,

self-closing stop valve. These two valves together with the

bubbler and bubbler guard formed an integral assembly. The adjustment for the pressure regulator was accessible by removing

the hexagonal nut holding the push-button on the bubbler assembly. Adjustments could then be made with a screw driver.

The bubbler assembly could be removed from the cooler by hand

without breaking the cooling unit insulation. Specimen S-10,

as originally submitted, did not meet the requirements of the

water regulator test. The test was repeated on the resubmitted

cooler, which then met the requirements for this test. The

test results are summarized in Table 5.

Specimen S-30 was equipped with three self-closing glass

fillers, located at the front of the cooler. Each glass filler

was equipped with a stream regulator, which could be adjusted

with a screw driver. Specimen S-30 did not meet the water

regulator test when originally submitted. When the cooler was

resubmitted, an automatic water regulator had been incorporated

into the water circuit of the cooler. This regulator was located in the top of the cooling unit housing; however, it was

not accessible for adjustment, repair or replacement. The test

was repeated when the cooler was resubmitted.

Table 5, which follows, shows the results of the water regulator test for specimen S-10 and specimen S-30.

TABLE 5. WATER REGULATOR TEST

SPECIMEN S-10

Water Supply Line

Pressure, psig

25 20 21

Stream Height above guard, in.

Stream Throw-distance, in.

Water Flow, ga^/min.

Percentage deviation from observed

flow at 35 psig

SPECIMEN S-30

Water flow from all glass fillers,

gal/min.

Percentage deviation from observed

flow at 35 psig

2 - 1/2 1 3

6 4-3/4 3-1/2

0.51 0.47 0.57

3 12

3.57

20

4.95

11

4.47

- 13

The deviation of 20$ for the flow at 20 psig on specimen

S-30 from observed flow at 35 psig does not comply with the requirements of the purchase specification. The maximum deviation

permitted by the specification is 15$.

(3) Freezing Test (Paragraph E-3, F-3i)

Each of the two cooler specimens had a control to prevent

freezing of the stored water in case of failure of the primary

thermostat, or other cause of abnormal machine operation. On

specimen S-10, this was a second thermostat, responsive to water

temperature. Specimen S-30 was equipped with a pressure control, responsive to evaporator pressure.

Both coolers were operated in accordance with paragraph

F-3i for 16 hours in an ambient temperature of 33°F 1 1°F. At

the end of the 16-hour period, water could be drawn from both

of the coolers, indicating that the freezing protection of both

specimens was adequate.

(9) Hydrostatic Test (Paragraph F-3a, F-3k)

In accordance with the requirements of paragraph F-3k(l)

and F-3k(2) of the purchase specification, a gas pressure test

was applied to the water and refrigerant containing parts of

the two cooler specimens. The water containing parts were subjected to a test at a pressure of 125 psig. The refrigerant

containing parts were subjected to a test at a pressure of 350

psig. No evidence of leaks, rupture, or damage were observed

on either specimen during the hydrostatic tests.

V. RESULTS OF INSPECTION

In order to determine compliance with other parts of the

purchase specification, both water cooler specimens were disassembled and detailed analysis was made of certain components.

Tests were made of the finish on the housings, of the thickness

of the plating on chromium-plated parts, of the corrosion resistance of screws, fastenings, and other metal parts, etc. The

following conclusions regarding compliance of specimen S-10 and

specimen S-30 with the requirements of the purchase specification

and its addenda are based on these tests and inspection of the

disassembled coolers. The comparison between the inspection results and the specification requirements is made paragraph by

paragraph using the numbering S3rstem employed in the purchase

specification to identify the requirement under consideration.

A-l. No comment required.

A-2. No comment required.

A-3a, A-3b. Neither cooler specimen S-10 nor cooler specimen S-30 had an Underwriters 1 label. It is not known whether

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any other evidence of compliance with Underwriters’ Laboratories

Standards was submitted to the purchasing agency.

A-3c, A-3d. No comment required.

B-l, B-2. Specimen S-10 was furnished as Type I, Size 10,

specimen S-30 as Type III, Size 30.

C-l. All materials used in the two coolers appeared to be

new.

C-la(l). Sixteen miscellaneous pieces consisting of plated

and coated parts such as screws, nuts, bolts, washers, portions

of the exterior covering of the water coolers and portions of the

galvanized tank, were removed from the two coolers and subjected

to a 4-hour salt-spray test conducted in accordance with Federal

Specification QQ-M-151. No significant corrosion was observed at

the end of the test on any of the pieces. A spectrographic

analysis of four samples of corrosion-resisting steel used for the

basin top of specimen S-10 and the drain tray and strainer assembly of speciman S-30 disclosed that the samples met the requirements for Class I material of Federal Specification QQ-S-763 or

QQ-S-766, as applicable, since concentrations of nickel and

chromium were within the following ranges:

Ni 9-10#

Cr 13-19#

When the insulation and storage tank were removed from the

cooler cabinet of specimen S-30, several large rust spots were

discovered on the bottom of the cooling unit housing. These rust

spots can be seen on Fig. 9. Although the inside of the cooling

unit housing appeared to have been painted, we believe that discontinuities in the paint surfaces caused the appearance of rust

spots. This portion of the cooling unit housing obviously did

not meet the requirements of paragraph C-la(l) with respect to

corrosion resistance and points up the need for better quality

control in the painting process.

C-la(2). Both specimens complied with requirements.

C-la(3). No tests were made by NBS.

C-la(4). No tests were made by NBS.

C-lb. Both specimens complied with requirements.

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C-lc. Six pieces of chromium-plated material was tested

for thickness of coatings. The nickel coating with a minimum

thickness of .00007 in. and an average thickness of .00009 in.,

on the glass filler of specimen 3-30 did not meet the requirements of Federal Spqdif ication WW-P-541. All other pieces

checked met the requirements of the specification, having minimum chromium thickness ranging from .000011 to . 00003 $ in., and

minimum nickel thickness ranging from .00010 to .00032 in.

C-2

D-l

D-la

for System

See item 9 under performance test results.

No comment .required.

Specimen S-10 complied with the requirements

T.

D-lb. No comment required.

D-lc. Specimen S-30 complied with the requirements for

System TM.

D-ld. No comment required.

D-2 , D-2a. Both cooler specimens complied with requirements.

D-2b. No comment required.

D-3a through D-3c. Both cooler specimens complied.

D-3d. The legs used on specimen S-30 did not comply with

the requirement. The adjustable portions of the legs were painted metal and were not made of corrosion-resistant polished metal.

The stati on erv portions were made of corrosion-resistant, formed

sheet metal having what appeared to be a mill finish rather than

either a "polished" or "satin" finish. Although the specification

contained no strength requirement for the legs, those on the

cooler appeared weak when sliding the cooler across a floor. A

representative of the manufacturer stated that the legs on the

production coolers would be different from the legs used on cooler

specimen S-30.

D-3e. Both cooler specimens complied with requirements.

D-4 through D-5. Both cooler specimens complied with requirements .D-6a. The organic finish on both cooler specimens was tested

and complied with the requirements of the specification.

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D-6b. Not applicable.

D-7 through D-7b. Specimen S-10 complied with the requirements. Paragraphs not applicable to specimen S-30.

D-7c through D-$a. Not applicable.

D-#b. Specimen S-30 complied. Not applicable to S-10.

D-$c. Not applicable.

D-9a. The adjustment for the water regulator on specimen

S-30 was not located in a conveniently accessible spot. Both

coolers complied with all other requirements of this paragraph.

D-10. The nickel plating on the glass filler of specimen

S-30 did not comply with the plating requirement (see comment

under C-lc). Both coolers complied with other requirements of

this paragraph.

D-llb. Both coolers complied with requirements.

D-llc. Both coolers complied. The water storage chamber

of specimen S-30 had a galvanized coating 1.34 oz/sq. ft. on

each side of the metal.

D-lld. The water spreader used in the precooler drain

passage of specimen S-10 reduced the internal dimension of the

drain passage to below 5 /$ inch. However, this type of construction is permissible under the interim specification for

electric drinking water coolers dated July 24, 1952, and in our

opinion, should be accepted.

D-lle. Both coolers complied with requirements.

D-12. No comment required.

D-12.a Specimen S-10 complied. Since charging valves were

provided in the refrigeration system of specimen S-30, this system

was considered ,T TMrt

. A readily-removable suction strainer was

not provided as required for this type system. Specimen S-30

complied with the other requirements of this paragraph.

D-12a(l). Not to be checked by NBS.

D-12b. Both coolers complied.

D-12c. Not applicable.

D-12d through D-13b. Both coolers complied.

D-13c.

D-13 d

- 17 -

Not applicable.

Both coolers complied with requirements.

D-14. Dichlorodiflouromethane (Freon-12) was used as refrigerant in both cooler specimens.

D-15a. Both cooler specimens complied with requirements.

D-15a(l). Specimen S-10 complied. The water piping on

specimen S-30 was copper tubing, not plated. This paragraph

required the use of galvanized steel pipe for water piping for

all coolers having a galvanized steel storage tank. However,

the interim specification for electric drinking water coolers

dated July 24, 1952, permits the use of copper pipe or tubing

for coolers having a galvanized steel storage chamber, provided

such pipe or tubing is plated with tin, nicke, or chromium on

the surface in contact with water. We believe that copper pipe

or tubing plated in this manner is acceptable for this cooler.

D-15b, D_i5b(l). Both coolers complied.

D-l6. No instructions for care and operation were received

with these coolers.

D-17a. Both cooler specimens complied with the requirements.

D-17b. The compressor and bubbler assembly on specimen S-10,

and the compressor and glass filler assemblies on specimen S-30,

did not have sufficient identification to comply with this requirement . D-17c. Not applicable.

D-18. No comment required,

E-l. Water storage tank on specimen S-30 had a capacity of

22.4 gallons. Both specimens complied with requirements of this

paragraph. For performance see item 1 under performance test

results

E-2 through E-$. Performance requirements. See applicable

items under performance test results.

F-l through F-2b. Not to be checked by NBS

F-3a through F-3k(2). Performance tests. See applicable

items under performance test results.

F-31o Not applicable.

F-4 through I. Not to be checked by NBS.

- 13 -

VI. CONCLUSION

The performance tests and inspection of the two cooler specimens indicated some deviations from the requirements of the purchase specification for both coolers.

Specimen S-10 essentially met all the performance tests after

resubmission, and, with the exception of certain labeling requirements and the precooler water spreader, met all the other applicable requirements of the purchase specification.

Specimen S-30 did not meet all the requirements of the following performance tests:

(1) Peak Draw Test

(2) Water Regulator Test

(3) Overload Test

With respect to construction and material requirements, specimen

S-30 did not meet all requirements for chrome plating, corrosion

resistance of housing, legs, location of water regulator storage

tank fittings, suction strainer in refrigerating system, water

piping, and labeling. Inspection disclosed that certain of these

failures to meet requirements could be remedied through better

quality control in the manufacturing process.

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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 by 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 technical 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 found in NBS Circular 460, Publications of

the National Bureau of Standards ($1.00). Information on calibration 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 Printing Office. Inquiries regarding the Bureau’s reports and

publications should be addressed to the Office of Scientific Publications, National Bureau of Standards, Washington 25, D. C.
I