NATIONAL BUREAU OF STANDARDS REPORT

2072

Model NM2B Electric Drinking Water Cooler

manufactured by

Sunroc Refrigeration Company

by

Henry Karger

Co Wo Phillips

Po Ro 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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r"

uNATiO^JAL BUREAU OF STAI^DA^DS REPORT

ms PROJECT NBS REPORT

1003-40-4700 November 20 ^ 1952 2072

Model NM2B Electric Drinking Water Cooler

manufactiired by

Sunroc Refrigeration Company

by

Henry Karger

Co Wo Phillips

Po Ro Achenbach

, Heating and Air Conditioning Section

Building Technology Division

to

Headquarters 5 United States Marine Corps

Department of the Navy

Washington 3 Do Co

The publication, n Approved for public release by the ir In part, Is prohibited

unless permission I Director of the National Institute of standards, Washington 25 , D. c, Such pe Standards and Technology (NIST) specifically prepared Ift Octobcr 9 201 i

Model NM2B Electric Drinking Water Cooler

byHenry Karger

Co Wo Phillips

Po Ro Achenbach

ABSTRACT

Two specimens of a pre=pro duct ion Model NM2B

electric drinking water cooler 5 manufactured

by the Sunroc Refrigeration Company, were

tested to determine compliance with Federal

Specification 00=C=566b, as modified by Invitation to Bid 7^2053 s» issued by Headquarters,

United States Marine Corps on June 13, 1951

One or the other of the two specimens were

found to be in compliance with most requirements

of the specifications as modifiedo The major

points of non-compliance for both specimens were:

(1) The coolers did not meet the performance

requirements regarding refrigeration

control

o

(2) The coolers did not meet the requirements

that internal water lines should be rigidly anchoredo

Since some deficiencies were noted on the second

specimen that were not observed on the first

specimen, and vice-versa, it was apparent that

better quality control and m.ore careful inspection

was needed to assure consistent quality in productiono
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INTRODUCTION

In accordance with requests from the Headquarters,

United States Marine Corps, in letters dated October 18,

1951 , and February 4? 1952, tests and inspections of

Model NM2B electric drinking water cooler manufactured

by Sunroc Refrigeration Company, Glenn Riddle, Pennsylvania, were made to determine compliance with Federal

Specification 00-C=566b, as modified in the Uo So Marine

Corps Invitation for Bids ^2053? dated June 13, 1951o

Two specimens of this model water cooler were utilized

in the testSo

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 c Conclusions

about compliance of the specimens with regard to materials

construction, and durability were drawn from the results

of inspections, plating tests, and other ph 3^sical and

chemical determinations with respect to the same Federal

Specificationo The tests required such detailed dismantling and sampling of construction materials of both

snecimen coolere that it was impractical to attempt

reassembly

o

DESCRIPTION OF TEST SPECIMENS

The two water cooler specimens submitted for test

were identified as follows

NBS Test Specimien 69“51» Specification Type I,

Size 10

Sunroc Company Model NM2B

Serial Number 211 944

Code Number 1-lOAHl

Identified in this report as specimen S-1

NBS Test Specimen 7^-52, Specification T^^pe I,

Size 10

Sunroc Company Model NM2B

Serial Number 214 732

Identified in this report as specimen S=2

Specimen S-2 was submitted after tests showed that specimen S-1 did not comply with certain of the requirements

of the specification as modified, hence the tests on sped

men 3-2 were in general confined to the points of noncompliance of specimen S-lo The outside appearance of

both specimen coolers was identicalo The^r were housed
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in formed, one-piece steel enclosures which constituted

the back and sides of the coolers o This housing enclosed

the condensing unit compartment and evaporator section

and provided structural support for the unite The solid

front panel could be rem.oved, 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 coolero All of the controls and electric connections were accessible from the front side

after the front panel was removed

o

A front view of specimen S-1 is shown in Figo lo

Figo 2 shows a rear view of the cooler, and the machine

compartment is shown in Figo 3 after remioval of the

front panel o Figo 4 shows the refrigeration unit after

removal from the cooler housingo A front view of cooler

specimen S-2 is shown in Figo 5°

The dimensions and weight of the coolers were as

follows o Height, iUo 44

Width of cabinet, iuo 14=1/2

Depth of cabinet, in.o 15

Width and depth of basin top,inol5=3/4

Weight, including wood

shipping base, 3b„ 145=1/2

The weight of the wooden base was approximately 10 Ibo

TEST PROCEDURE

The laboratory investigation of the specimens made

to determine compliance with Federal Specification

00-C-566b was divided into two main parts o First, tests

were made to determine compliance with the performance

requirements of the following paragraphs of the specifica

tion some of which were modified in the Invitation to Bid

(1) D-1, E-1, F-3a

(2) D-la, F=3d

(3) D-lb, F-3b

(4) D-6a

(5) D-6d

(6) D-lOd

(7) D-lOd(l)

(^) D-llb

(9) D-13a

(10) D-13b

(11) F-3c, D~lla

Capacity Test

Peak Draw Test

Maximum Operating Test

Jet of Water

Water Regulator and Valve Test

Refrigeration Control Test

Freezing Test

Motor Overload Protection Test

Operation at Varying Water Pressure

Drain Capacity

Overload Test

= 4 -

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, etCo

All performance tests listed above were conducted

in a temperature-controlled room under the general conditions 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 conditionso Temperatures were measured by means of calibrated thermocouples using an electronic, constant-balance

type of potentiometer 0 Accuracy of this instrument was

checked at intervals during the tests by means of icebath references o Inlet and outlet drinking water temperatures were measured by thermocouples in thin-walled

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 o 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 deviceso

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

detailso

PERFORMANCE TEST RESULTS

The following paragraphs show the results obtained

on specimens S-1 and S-2 during the performance tests listed under the section on Test Procedure

o

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

Table 1, which follows, summarizes the results obtained during the capacity test on specim-en S-1 and compares

the observed perforniance with the specification requirementSo 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 °Fo
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Table 1 shows that the observed capacity of specimen S=1 exceeded the required capacity for Type I,

Size 10 coolerso

TABLE lo CAPACITY TEST OF SPECIMEN S-1

Required Observed

Performance Characteristics Performance Performance

Ambient Temperature ^ ®F 90 90,^2

Electric Power inputs watts = 2?^

Terminal Voltage 110 110

Total Current Input, amps - 3o6

Drinking Water, Inlet 'S'empo, °F SO 79o4

Drinking Water, Outlet tempo, ®F 50 50o3

Drinking Water, Tempo Diff

,

®F 30 29ol

Spill through precooler, % 60 60o7

Drinking Water flow rate, observed, gph - llo3

Drinking Water flow rate, corrected

for a 30°F tempo difference, gph 9o0 10o9

(minimum)

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

The specification as modified in the Invitation to

Bid specified that 37'”l/2 percent of the required hourly

capacity shall be drawn off in 15 minutes o The water

temperature at the beginning of the 15“minute period must

be not lower than 45°F or higher than 50°F .and shall not

rise more than 10 degrees at any tim.e during the 15'=minute

periodo The water must be drawn off, beginning immediately

after the compressor-motor cuts off in a normal cycle, in

not less than three or more than six equal intervals per

gallon of required draw-off capacityo The water must be

drawn off at a rate of not less than 1/2 gallon per minute

per bubbler o It was assumed that in accord with general

requirements of paragraph F-la? 60^ of the cooled water

should be allowed to flow through the precooler as water

was being draitoo

For this test, the specimen coolers were equipped with

self-closing hand-operated valves adjusted to permit water

to flow at a rate of l/2 gallon per minute when openedo

Water was drawn from both specimens in 54 equal samples,

each consisting of a 40^ portion, drawn first, and a 60>

portion, drawn second o The U0% portion was poured into a container for subsequent weighingo It simulated water consumed and did not pass through the precoolero The 60%

portion was poured into a vessel of low thermal mass immediately prior to each subseouent drawo This vessel

allowed the 60% portion to flow through the precooler

during the time required for the entire subsequent draWo
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Specimen S»lj as submitted, did not ^meet the peak

draw requirements, primarily because of the inability

of the compressor motor to start on thermostat demand in

time to prevent delivery of outlet drinking water in excess of oO°F soon after the start of the peak draw testo

Installation of a motor-starting capacitor by representatives of the Sunroc Company permitted pronipt starting

on thermostat demand and overcame this difficultyo

Because the original thermostat in Specimen S-1

failed to meet the requirements of the refrigeration

control test, three additional, thermostats were installed in this water cooler during the course of the testSo

Since compliance with the peak draw requirements depends

on the thermostat performance additional peak draw tests

were made with the other thermostats in an effort to find

one that would permit the cooler to meet the requirements

of both the peak draw test and the refrigeration control

test o Three peak draw tests were made using thermostat Noo

2 in specim.en S-1 with initial outlet drinking water temperatures of 4^o7°F, 46 o 5°F, and 49o4°F and temperature rises

of 9o5°Fj llo2°F, and 10o7°F, respectivelyo Since outlet

drinking water temperatures • in excess of 57°F were observed

in all peak draw tests made, it was evident that peak draw

reouirements could not be met unless the initial outlet

water temperature was above 47®Fo Compliance with the peak

draw requirem.ents was indicated in one of the three tests

described above, but even with an initial water temperature

above 47°F there vias an element of chance in the matter of

compliance as evidenced by the third test which showed a

temperature rise oflC,, 7^F with an initial water temperature

of 49o4°Fo

A peak draw test was not made with thermostat 7^3 <> However, the time response of thermostat in starting

the compressor-motor under peak drawn test conditions was

identical to that for thermostat //2, which permitted the

cooler specimen S-1 to meet one peak draw testo It w’-as assumed, therefore, that thermostat 7^3 would have been

equally satisfactory for the peak draw requirementSo

Compliance with peak draw requirements was not observed

when using thermostat in Specimen S-1, This was the only

thermostat which met the requirements of the refrigeration

control test, as outlined under Section 6 of the Test ResultSo

Thermostat 7^4 caused the cooler to fail the peak dra,' test

because the time response was not prompt enough in demanding

compressor operationo

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A peak draw test was made with cooler specimen S”2o

With an initial water temperature of 49o2°F^ the rise of

outlet drinking water during the peak draw test was observed to be 7 oS°Fj hence this cooler was in compliance

v/ith neak draw requirement s o It villi be noted that neither

water cooler specimen met the requirem.ent s of both the peak

draw test and the refrigeration control test with a given

therm.ostat o

( 3 ) Maximum Operating Test (Paragraphs D=lb^ F=3b)

The specification required that the cooler should

start and operate satisfactorily, and should be operated

continuously^ for at least & hours under conditions of 110°F

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

outlet drinking water temperature, and, it was assumed in

accord with paragraph F- 3 a, with o0% spill through the

precooler

o

Specimen cooler S-1 was operated for eight hours under

the above conditions o At the conclusion of the test, the

cooler was turned off and left idle for a period of five

m.inutes and then restarted to determine whether or not it

would start satisfactorily without causing the motor overload mechanism to operateo The cooler started and onerated

satisfactorily during this testo

Table 2 , which follows, shows the average conditions

maintained during the maximum operating testo

TABLE 2o MAXIMUM OPERATING TEST OF SPECIMEN S-1

Required Observed

Performance Characteristics Performance Performance

Electric Power input, watts

Terminal Voltage

Total Current input, amps

Ambient Temperature, °F

Drinking Water, Inlet tem.po, °F

Drinking Water, Outlet tempo, °F

Drinking Water, tempo diff o , °F

Spill through precooler, %

Drinking Water flow rate, observed, gph

Drinking Water flow rate, corrected

for a 50°F tempo difference, gph

=. 292

110 110

3o7

110 109 0 9

100 lOOo 2

50 4919

50 50o3

60 60o3

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(4)

Jet of Water (Paragraph D-=6a)

The position of the jet of water relative to the ori~

fice, guard, and cooler basin was observed and was found

to be in compliance with the specification requirements

for specimen S-lo

(5)

Water Regulator and Valve Test (Paragraph D”6d)

Both specimen coolers were equipped with an adjustable

automatic wat er=pressure regulating valve and a handoperated, push-button type, self-closing stop valve

o

These two valves together with the bubbler and bubbler

guard formed an integral mechanismo The adjustment for

the pressure-regulating valve was accessible by removing

the hexagonal nut holding the push-button on the bubbler

assemblyo 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

Observations were made of the stream height, throw dis

tance, and rate of water discharge on cooler specimen S-1

for inlet water pressures of approximately 20 psig and 75

psigo The results are summarized in Table 3, which follows

Water did not spurt from the bubbler of the specimen

cooler when the stop valve was opened except when purging

air during the initial filling of the cooler® No objection

able splashing of the drinking water on the cooler top was

observed®

TABLE 3® WATER PRESSURE REGULATOR PERFORMANCE-SPECIMEN S-1

Supply Water Pressure, psig

Stream Height above nozzle, in®

Stream Height above guard, in®

Throw distance from nozzle, in®

Rate of Water Flow, gal/hr

(6)

Refrigeration Control Test

20 75

3-1/^ 3-3/^

1-3/^ 1-5/^

.6 6-1/2

19o5 20o6

( Paragraph D°

modified)

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The specimen coolers were equipped with therm.ostats

,

actuated by refrigerant and incoming water temperatures,

which controlled the operation of the compressor motor®

The thermostats were readily accessible for adjustment and

servicing when the front panels of the coolers were removed

and could be replaced without breaking the main insulation

of the cooling unit housing®
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The requirements of paragraph D-lOd^ as modified in

the invitation to bid^ were interpreted by the United

States Marine Corps in a letter to the Sunroc Company dated

December 12, 1951? as follows?

"Refrigeration control shall be by means of an

adjustable thermostat having a single j external

controlling device (knob)o The thermostat shall

be capable of causing delivery of outlet drinking

water in a range of from 45 degrees to 55 degrees

fahrenheitj, or higher ^ at any one rate of outlet

drinking water withdrawal o A differential ^ not to

exceed plus or minus -5 degrees fahrenheit at any

control point j shall be permitted o The control

point of the outlet drinking water shall be defined as the 'average temperature reading of outlet

drinking water taken at equal intervals in time,

or at the time of every thermostat operationo

The differential shall be defined as the maximum

permissible exclusion (excursion) from the control

point o It shall not be possible, by means of the

single, external thermostat adjusting knob, to

cause delivery of outlet drinking water having a

tem.perature of less than 40 degrees fahrenheit,

under any condition of flowo”

Adjustment of the thermostat on both specimen coolers

could be effected by turning a knob, which had a dial divided into seven positions, numbered from 1 to 7° An arrow

on the dial indicated the thermostat would cause the cooler

to deliver colder water when the knob was turned to the

higher numbers on the dial, ioeo position number 1 would

be the warmest position and position number 7 would be

the coldest positiono

The requirement outlined above was interpreted by this

Bureau to mean that the cooler should, be capable of delivering drinking water at any one rate of water withdrawal at a

temperature of 45°F or lower for the coldest setting of the

thermostat adjusting knob (position ^7), and at a temperature of 55°F or higher for the warmest setting of the

thermostat adjusting knob (position §l) o For the purpose

of this test it was assumed by this Bureau that compliance

at one of the following two rates of water withdrawal

would be sufficient to show compliance with the range and

differential requirements and at both rates to show compliance with the minimum delivered water temperature requirement o The first of these was a nominal no-load draw-off

rate, during which approximately l/24th of the required

hourly capacity was withdrawn intermittently through the
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bubbler per houro The second was a half-load draw-off

rate, during which approximately 1/2 of the required

hourly capacity was withdrawn intermittently through

the bubbler per houro

For the no-load test, two 6~ounce samples of water

were withdrawn every 15 minutes, and the temperature of

the second sample was recordedo For the half-load test,

two 6-ounce samples were withdrawn every minute and

fifteen seconds, and the temperature of the second sample

was recordedo The tests were conducted in an ambient

temperature of 90°F, and the inlet water temperature was

maintained at a temperature of ^0°Fo

Four thermostats were installed successively on

Specimen S-1 by representatives of the Sunroc Company in

connection with this requirement and the peak draw requiremento Only thermostat jf4 met the requirements of paragraph D-lOid, as interpreted by the United States Marine

Corps o However, the cooler did not meet peak draw requirements using thermostat jfko It was the understanding

of this Bureau that the performance of the cooler, specimen

S-1, was to be judged with respect to its ability to control

outlet drinking water temperature on the basis of operation with thermostat ^3? indicated by the Sunroc Company as

their standard thermostat o Thermostat ^3 had insufficient

range adjustment to comply with the above quoted requirement o During the half-load test, the lowest outlet drinking water temperature observed at the lowest setting of

the therm.ostat (position §7) was 41o9°F and the highest

temperature observed at the highest setting (position ^1)

was 49o4°Fo During the no-load test, the lowest outlet

drinking water temperature at the lowest setting of the

thermostat (position §7) was 49o9®F, and the highest temperature observed at the highest settling (position §1) was

57oS°F„ Hence the requirement that the temperature control

be adjustable in a range of from 45°F to 55°F was not met

for either of the two chosen test conditionso

Additional thermostat tests were made with specimen

cooler S-2o Again, it vms found that the thermostat had

insufficient adjustment range to comply with the requirementSo For this specimen cooler, during the half-load

test, the lowest outlet drinking water temperature observed

at the lowest setting of the thermostat (position ^7) was

40o9°F, and the highest temperature observed for the highest setting (position ^1) was 49o9°Fo During the no-load

test, the lowest temperature observed at the lowest setting

was 51ol°F and the highest temperature observed at the

highest setting was 6lo2°Fo
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(7) Freezing Test (Paragraph D»10d(l) Modified)

Eaeit water cooler specimen had an additional thermostat, non-ad justable external to the thermostat housing,

to serve as a protective device against freezing. The

freezing test was made with specimen cooler S-l, The primary drinking water thermostat was shunted, and the

cooler was operated for 16 hours in an ambient of 33°F,

At the conclusion of the test, drinking water could be

drawn from the bubbler, indicating that the additional

thermostat had controlled the compressor motor operation

to prevent freezing of water in the cooler,

(S) 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 o”

Both specimen coolers were equipped with such a device, Tests were made with specimen S-l, To determine

tlie protection afforded, two tests were made, both in

a 90°F ambient temperature, with supply water flowing

steadily through the cooler at a rate slightly in excess

of 30 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

temperatures at the time of cutout were no longer increasing and the temperature rise of the winding was computed

on the basis of the highest resistance observed. The highest motor winding temperature observed under these conditions was 194°F, Second , the condenser fan was disconnected, and the cooler was allowed to continue in oneration. The motor winding in the cooler reached temperature equilibrium after approximately 1 hour operation,

and the protective device did not function during the

test. The test was terminated at this time. The average conditions observed during the period of temperature

equilibrium are listed in Table 4> which follows

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TABLE 4. OPERATING CONDITIONS OF COOLER

SPECirai S»1 DURING SECOND NOTOR

OVERLOAD PROTECTION TEST

Temperature of Compressor Dom_ej under

protective element, ®F l62oO

Temperature of Inlet Water to Cooler, °F ^0o6

Temperature of Outlet Water from Cooler, °F 70o0

Temperature of Ambient Air, ®F 92 o2

Temperature of liquid refrigerant

leaving the condenser, ®F 140o2

Compressor Motor Current, amps 3o9

Based on present accepted oractice in the design of

hermetic motor-compressor units, it is the opinion

of this Bureau that the compressor motor in the

specimen cooler was satisfactorily protected against

overload and against excessive temperatures caused

by motor overload

o

(9) Operation at Varying Water Pressures

(Paragraph D~13a modified)

As required by the specification in paragraph

D-13a, cooler specimen S~1 operated satisfactorily

when connected to a water supply system at pressures

ranging from 20 psig to 75 psigo The capacity test

specified under paragraph F-3a and described under section 1 of this report was made with a supply water

pressure of approximately 23 psigo The perform*ance of

the water regulator and valve under supply water pressures

of 20 psig and 75 psig is discussed under section 5 of

this report

o

(10) Drain Capacity (Paragraph D=13b m.odified)

The drainage system of cooler specircien S=1 was free

of internal trappings and did not cause stoppage of

water in the bubbler basin

o

(11) Overload Test (Paragraph F=3c, D-lla modified)

Cooler specimen S-1 was tested in accordance with the

requirements of paragraph F=3c of the specification, which

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

with water drawn at the rate of 300 percent of the required hourly capacity, with 60^^ spill through the precoolero The inlet water temperature was held at a temperature of approximately ^0°Fo The results of this test

are summarized in Table which follows

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The specimen cooler operated satisfactorily and

without any indication of breakdowno The temperature

rise of the motor running winding was determined by the

resistance method and computed by the formula given in

paragraph 4o2»3 of Federal Specification CC~M-='636a,

dated October 29, 1951 o Table 5 shows that the temperature rise of the motor winding was well below the permissible rise for totally enclosed motors in this specif icationo

It is pointed out that Federal Specification

CC-M-636a does not carr^r any reference to motors integral

to a hermetically-sealed refrigeration compressoro It

is believed that the coil winding temperature rise

limits for totally enclosed type m.otors should serve

as a guide to assist in judging hermetic motors.

Electrical components^ external to the hermeticallysealed motor, appeared to be adequate and suitable on

the cooler specimens,

TABLE 5, OVERLOAD TEST OF SPECIMEN S-1

Required Observed

Performance Characteristics Performance Performanc

Ambient temperature, °F 100 101,1

Drinking water, inlet temp,, op ?^2,1

Drinking water, outlet temp,. op 6^,7

Ratio of drinking v/ater flow

flow required for capacity,

to

test 300 300

Spill through precooler, % 60 60,3

Electric power input, watts = 32 cS Terminal voltage 110 110

Temp, rise of motor windinc^s, 32,6

RESULTS OF INSPECTIOF

In order to determine compliance with other parts

of the specification, both water cooler specimens were

disassembled and a detailed analysis was made of certain

components. Tests were made of the finish on the housing,

and the thickness of the plating on chromium-plated parts

was determined. The majority of these tests were made

on cooler specimen S-1, while cooler specimen S-2 was

Inspected only to determine certain construction features,

which, on cooler specimen S-1, did not comply x-^ith the

requirements of the specification.
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14

Results of Inspection on Specimens S=>1 and S“2o

The following conclusions regarding compliance of

specimens S“1 and S=»2 with the requirem.ents of the Fed=

eral Specification, as modified for this invitation,

are based on the above mentioned tests and inspection

of the disassembled coolers o The comparison between

the inspection results and the specification require^

ments is made paragraph by paragraph using the numbering s^T’stem in Federal Specification 00=>C=566b, dated

July 31 j 1947j as modified to identify the requirement

under consideration

o

A-lo No comment required

»

A-2o No label or marker is visible on cooler nameplate or cooler cabineto

A-2ao Not to be determined by this Bureauo

A-2b<, No comment required =

B“lo Sample cooler furnished was to be considered as Type I size lOo

C-lo All materials used appeared to be newo No

materials unsuitable for their intended purposes were

observed under the type of inspection requested

o

C-la(l)o No tests were made» Inspection indicated

the all bolts, nuts, pins, screws, and other fastenings

and fittings had some sort of surface protection against

corrosiono

C-la(2)» No tests were madeo Inspection indicated

that rust of cabinet material had formed around the holes

drilled to receive sheet metal screv^s after original rustproofing of the metal, around other openings, and near

spot welds

o

C-la{3)o Inspection indicated complianceo

C-lb„ Inspection indicated complianceo

C-lCo Tests of chromium plating showed complianceo.

C-2o There is no yardstick known to this Bureau for

first-class workmanshipo On specimen S-1 the cooling

unit housing sections were joined with an insufficient

number of spot welds to insure the rigidity necessary

to prevent damage to the vapor sealo

“ 1.5

On specimen S“2, an improi^'ement was noted in the

construction of the cooling unit housing with regard

to spot welds and general rigidity of the housingo An

extra plate ^ shown by the arrow on Figo 6 was welded

in below the front cooling unit housing panel and added

greatly to the stiffening of. the housingo In the opinion

of this Bureau^ the cabinet construction on specimen S-2

was adequate

o

C=3 o Inspection indicated compliancec

D“lo No com.ment required

o

D“lao See discussion of performance tests

( section 2 )

«

D-lbo See discussion of performance tests

( section 3 )

»

D“2o This Bureau is not in a position to determine

compliance with the ’^current production’’ requirement o Cooler complied with all other applicable requirements

of this paragraph

o

D=2ao Cooler complied with requirements „ In order

to rem.ove the high and low side as a unit from the cooler

it was necessary to remove the insulationo

D“3ao Inspection indicated compliance

o

D“3bo Inspection indicated complianceo

D=4o Tests showed that the exterior of the cabinet

was covered with an organic finish and that both interior

and exterior surfaces were painted

o

D~4ao Paragraph not applicable

»

D”4bo Tests indicated comiplianceo

D“5o Inspection indicated com.plianceo Acidresisting test of vitreous-porcelain china was not

made

»

D-6 . through D-6e Inspection and tests showed

complianceo

D=6fo Paragraph not applicable <, D-7o Paragraph not applicable

o
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D°^o Inspection and tests showed compliance

o

D“=9o No comment required

o

D“9ao Inspection indicated compliance on specimen

S“lo Inspection indicated tin plating on the interior

of tube used for x^^ater cooling and storage o

!''Jhen attemps were made to determine whether the

cooler specimen S-2 could be drained completely^ it was

found that the plug sealing off the drain connection at

the rear of the cooler was stuck sufficiently tight in

the casting that the two screws holding the drain plug

casting to the back cabinet panel sheared off without

loosening the plugo The casting^ with the plug and the

sheared“Off screws j can be seen in Fig„ 7„

Ifhen the cooler was opened subsequentl3r for inspeC“

tion of the cooling unit housing^ it was found that the

evaporator was mounted in the housing at an angle of approximately 15 degrees from the vertical o This can be

seen in Figo This photograph is a top view of the

evaporator housing, showing the cooling coilo "^Aliile this

probably would not affect the ability of the cooler to

deliver cooled water, it is believed that an evaporator

coil mounted at such an angle would not permit complete

drainage of the water storage coil, as such drainage is

entirely dependent on gravity flow of water

o

The cooling coil in specimen S-1 was satisfactorily

mounted in a vertical position and was capable of being

drained

o

D-9bo Inspection indicated compliance

o

D-9Co Cooler corapliedo At one point in the precooler drain tube one internal dimension of the free area

was less than 5/^ incho This was caused by a splash plate

in the top of the precooler which directs the flow of

spilled watero

D”9do Some discontinuities were observed in the vapor

seal on specimen S-lo (See also discussion under paragraph

C-2 regarding spot welding of cabinet sectionso) The cooler

complied with other requirements of this paragraph

o

Inspection of specimen S-2 disclosed two voids in the

insulation, each having a volume of approximately five

cubic incheso It is believed that these voids were caused

by the bubbler and glass filler lines which formed a bridge and prevented complete filling of the cooling unit

housing with insulationo
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D=10o No comment required

o

D-lOao Cooler complied with requirementSo

D=10bo Inspection indicated complianceo

D=10co Paragraph not applicable

o

D-lOdo Refrigeration control did not comply with

performance requirement So See discussion under performance tests (section 6K

D-lOd(l) Cooler compliedo See discussion under

performance tests (section 7)o

D“llao Cooler complied with the requirements o It

should be noted that it was necessary to install a starting capacitor to meet peak draw requirements o See discussion under performahce tests (Section 11)

o

D-llbo Cooler complied with the requirement s o See

discussion of motor overload protection test (section o D-llCo Paragraph not applicable

o

D-lldo Cooler complied with the requirementSo

D=12o Cooler complied with the requirementSo

D»13ao On specimen S-l the water tubes from the

evaporator coil to the bubbler and glass filler outlets

were not anchored in a suitable manner and hence were

susceptible to twisting when bubbler or glass filler outlet cap was removed and replaced for any reason » Cooler

complied with other requirements of this paragraph,,

On specimen S-2 improvement was noted in the anchoring of the bubbler line, in that thicker rubber washers

were used to provide frictional forces to lessen the likelihood of line twistingo However^ a positive means of

anchoring the bubbler and glass filler lines ^ such as

stops or bosses, was not providedo A determination of

the torque necessary to twist the bubbler line through

90 degrees was madeo In preparation for this test, the

bubbler assembly was removed and the "pal nut" anchoring

the line was tightened securely,, It was found that approximately llo5 Ib-ft (13^ lb-in), was needed to twist

the line 1/4 turn in about 45 seconds, the force being

applied steadily during that timeo The torque necessary

to restore the line to its original position was approxi-

mately 6 Ib-ft. (72 lb-in) * Since the bubbler and guard

assembly provided a maximum lever arm of 1-1/2 inches,

a force of about 90 IbSc would have been required on the

extreme end of the bubbler assembly to duplicate the original twisting effort describedo It was found that such

a force was not required to properly install the bubbler

assembly,,

Removal of the bubbler assembly, if it were stuck to

the mounting stud by corrosion, or if the "pal nut" were

not tight, could result in twisted lines o On the specimen coolers submitted, the glass filler and bubbler lines

were sufficiently flexible to allow raising of the top

such that a tool could be used to reduce the likelihood

of line twistingo

In the opinion of this Bureau, positive anchoring of

the bubbler and glass filler lines is superior to the

anchoring method observed but satisfactory service can

be expected from coolers identical to specimen S-2 as far

as the likelihood of line twisting is concerned, if careful

and intelligent servicing is practicedo However, the requirement in paragraph D-13a that "All piping and tubing

shall be rigidly secured in proper position in such a

manner that when connections are made to external drain or

drains and water lines no strain will be placed on internal

piping" was not complied witho

D-13bo Cooler complied with the requirement So

D-13Co Cooler complied with the requirementso

D-13do Water containing parts of the cooler were subjected to a hydrostatic pressure of approximately 120 psig

during the freezing testo No leaks were observed in joints

or other water-containing partSo However, the bubbler stop

valve leaked at a pressure of 120 psig, and continued to

leak at a rate of approximately 1 gallon per hour when the

pressure was reduced to 60 psigo An examination of the combination stop- and regulator-valve did not disclose any

obvious ruptures, and it is believed that the leak was caused

by particles of foreign matter which were forced into the

valve seato The refrigerant-containing parts withstood

the hydrostatic pressure testo

D“14o Not to be determined by the National Bureau

of Standards^

D-15o Cooler complied with requirements of this

paragraphs

D-l6o Not to be determined by the National Bureau

of Standards 0
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E=>lo Cooler complied with applicable requirementSo See discussion under performance tests

( section 1 )

o

E=2 through E-7do Paragraphs not applicable

o

F=1 and F“2o Mot to be determined by National

Bureau of Standards

o

F=2ao See discussion under paragraph D=13do

F”3a through F=3do Cooler complied with requirementSc See discussion under performance tests

(sections 1, 2, 3s and ll)o

F“4o Paragraph not applicable

o

F»59 F“5a, F-5be No tests madeo

F“>6o No comment required o G-1 through I“6o Not to be determined by the

National Bureau of Standards

o

CONCLUSION

The performance tests and inspection of the two

specimen water coolers indicated some deviations from

the requirements of Federal Specification 00=-C->566b^

as modified in the invitation for bids ^2053 o Of these

deviations^ those for which both test specimens provided

less than was required are listed below:

lo Neither specimen met the performance requirements for the refrigeration control o (Paragraph D-lOd)

2o Neither specimen met the requirement that lines

should be rigidly anchoredo (Paragraph D=13a)

Specimen S=2 was submitted by the manufacturer because of deficiencies in specimen S-1 x^ith regard to discontinuities in the vapor seal, cabinet construction,

refri^^eration control, peak draw capacity, anchoring uf

the bubbler lines o This second specimen vas satisfactory

v/ith respect to the vapor seal, cabinet constructicr , and

peak draw capacity and showed im.provement in the method

of anchoring the bubbler and glass filler lines » It did

not meet the performance requirements for the refrigeration
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control or the construction requirements for rigid

anchoring of the water lineso In addition the second

specimen had voids in the insulation, a tilted evaporator which prevented free draining of the water, and a

drain plug which could not be removed without twisting

the water line connected to it. Inasmuch as these

three deficiencies, the stuck drain plug, the misaligned

evaporator coil, and the voids in the insulation, observed

on cooler specimen S-2, were not noted on cooler specimen S-1, it is believed that they were not necessaril37-

indicative of consistently poor production, but rather

of need for improvement in quality control

o


4
FIGURE 2
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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 hy Congress in Public Law 619, 1950.

These include the development and maintenance of the national standards of

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