NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT

1003-20-4891

nm »£s>osrr

6221

November 24, 1958

PROGRESS REPORT ON CONDENSER STANDARDIZATION

(MAY 1 TO OCTOBER 31, 1958)

QM.REL-M PROJECT ORDER NO. 57-26

by

F. J. Jerome Drapeail and Clinton W. Phillips

Air Conditioning, Heating, and Refrigeration Section

Building Technology Division

to

Mechanical Engineering Division

Quartermaster Research and Engineering Command

Natick, Massachusetts

IMPORTANT NOTICE

NATIONAL BUREAU Of

intended for use within

to additional evaluation

listing cf this Report) ell the Oltlce of the Directoi however, by the Governn

to reproduce additional 1

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST) on October 9, 2015.

1 or progress accounting documents

is formally published it Is subjected

ntlng, reproduction, or open-literature

emission Is obtained in writing from

I. C. Such permission 9 s not needed,

Icaily prepared If that agency wishes <jgs>

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
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PROGRESS REPORT OK CONDENSER SWimARDIZAlIOH

POE THE PERIOD MAY 1 TO OCTOBER 31, 1958

QMRBL-M, PROJECT ORDER NO. 57-26

The activities described in this report follow in sequence

those reported in a letter addressed to ft* J. Campbell and dated

May 2, 1956.

I Activities During May 1958

Installation was completed of the condensing units for temperature control in the calorimeter and test room* together with

most of the necessary control devices. Installation of electrical

circuits for power and control equipment was continued.

Construction of the receiving and discharge chambers, in

accordance with ASRK P.S.2.4, was completed, together with the

connecting devices for adapting the condensers to the receiving

chamber,

A multi-purpose instrument and system control center was

erected adjacent to the test cell, and the Instrumentation of

this room was begun,

II activities During June 1956

The air cooling unit for the test cell was received and Its

installation was completed together with the necessary controls,

piping, and electrical circuits, Work on instrumentation in the

control center continued throughout the month

,

The components of the air circuit were treated for rust

prevention and Installed In the test room as an integral unit.

Including the flow nozzle, pitot tube, and air flow control

damper. The receiving chamber was insulated as specified in the

proposed standard. The exhaust blower was installed and the

entire system was leveled and aligned.

The installation of pressure and temperature measuring instruments for the system was started during the month. Other

instruments and equipment were installed as they were received.

Fabrication of the evaporator for the system was completed

following receipt of the heating elements, and with its installation,

construction of the major items of the calorimeter was completed.
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The refrigerant circuit of the test apparatus, complete

with a remote air-cooled Size a, Class 1 test condenser, motor,

and fan mounted in the apparatus, was put in operation to try

out the system. During this trial run, two of the evaporator

heating elements hurried out, apparently because the protective

devices on the surface of the evaporator tubes failed to sense

the heater element temperature . The calorimeter evaporator was

dismantled to determine the extent of the damage and to replace

the heating elements. It was decided to replace all the heaters

with others of lower watt density, and the necessary elements

were ordered.

Ill Activities During July 1958

Instrumentation of the test control room and Installation

of pressure and temperature measuring circuits in all related

apparatus wore completed,

The entire refrigerant circuit of the apparatus was dismantled and all parts were cleaned or replaced as necessary

because of the decomposition of the refrigerant- in contact

with the overheated electric elements . alterations were made

to Improve system operation and to reduce the likelihood of

further major damage.

as agreed in a meeting between representatives from :.turtettaasfcer Bese&rch and Engineering Command and this Bureau,

it necessary, before testing any of the prototype conaensere, to determine that the fan used with each test condenser

was in conformity with the minimum air flow requirement of the

purchase description. It was necessary, therefore, to thoroughly

test each fan before tests of the corresponding condensers could

be started,

in order to conduct a fan performance teat in accordance

u paragraph k0M*M of Purchase Description dated March i 1957,

the fan orifice of a Size A Kramer Trenton condenser was removed

and altered to conform to HARM bellmouth design specifications.

'This alteration was completed during the month and the fan

performance test phase was begun. It should be noted that the

air circuit in the test apparatus required in ASRE Proposed

standard 2.4 ia not identical to the fan testing apparatus described in BAFM Plate VI, which is referenced in the fan requirement of the purchase description.
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IV Activities During; .sugust 1958

A Torrington d-1826-3 fan two mounted as shown in NAFK

bulletin No. 110, *nd edition, Plate VI for the first series

or fan testa. It was operated in an 18-5/16 -inch bellxricuth

at 1140 rpm with one third of the blade pitch extending downstream of the hellmouth. Teats we^e made over a range of static

pressure difference from 0,00 to 0.60 in. K.G. at standard air

conditions of 68 F dry bulb and 50$ relative humidity. In the

static pressure range from zero to 0,25 in* «. 0* the ^an did

not meet the minimum air flow requirements specified In Drawing

5-13-1863 of the Proposed Military standard. It failed by as

much as 15 percent in this operating range.

Following several refinements of the air circuit in the

test apparatus other fans on hand of Torrington Series E-1026-3

were tested, all of which failed to meet the specified minimum

capacity.

A telephone conversation with engineering personnel at the

Torrington Manufacturing Company revealed that the whole shipment of Series F-1826-3 fans received by this bureau were

deficient in pitch depth by 3/16 inch or more. The design depth

was 4-7/16 . series B-1026-3 funs of the correct pitch were

requested and arrangements were made for a representative of

this Bureau to visit the fan testing facilities of the manufacturer in Torrington, Connecticut.

V -activities During .September 1958

An MBS representative went to the Torrington Manufacturing

Company during the early part of the month to discuss with their

engineering personnel the problem of obtaining proper fans for

the condenser tests. Testing methods were compared, and Torrington test facilities were inspected at this meeting. The

company promised prompt shipment of the proper fans for the small

condensers and cooperation in furnishing correct fans for the

larger size condensers when the need arose.

Three condensers, complete with motors and fans, shipped by

the Kramer Trenton Company and received by this Bureau on February 6, 1958, UBS nos. 142-58, 143-58, and 144-53, were equipped

with Torrington Series E-1829-3 fans. Test^ were made using

one of these fans which was short in pitch t>y 1/8 from the

design depth for this blade of 4-15/16 . This fan al^o failed
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to meet the air flow requirements listed in the 1954 edition

of the Torrington Airistoerat for the E- 1029-3 f&n, but only

by a maximum of 3 percent at 0,00 E-0 3.P., and less than

3 percent at higher static pressures. These fans were designed

for higher air delivery than the E-1026-3 series and could not

be used for the condenser test because they deliver more than

the required air flow specified In the purchase description.

For example, the purchase description requires 2070 efm at

0.2 in, W.G.; the $-1329-3 fan delivers 2160 cfm at 0,2 in. W.G.

At lower static pressures, this disparity was greater.

Hie shipment of B- 1826-3 fans of correct pitch requested

from Torrington Manufacturing Company arrived, but they were

of the blow-through instead of the requested draw-through type.

They could not be used and shipment of the correct type was

requested.

Before receiving the correct fans, alterations to the air

side discharge chamber were made to bring this system into closer

agreement with the requirements set forth in MASf4 Fan Test Codes,

These alterations consisted of lengthening the duct beyond the

nozzle discharge, installation of an ' egg crate” air sfcmightener,

and flaring of the air passage from the discharge of the bellmount into the receiving chamber. In order to mount the fan

motor in the receiving: chamber, the connecting duet was eliminated, This "change should be incorporated ABBE Proposed standard

2.4.

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-A shipment of two E- 1026-3 fans of correct pitch and rotation

arrived at the end of September,

A Class 1, Size 3 Thermo King condenser was received for

testing. It was shipped without fan, fan motor, shroud, or fan

orifice,

VI Activities During October 1958

One of the new shipment of Torrington F- 1026-3 fans was

tested at standard air conditions and met the minimum air delivery

requirement at 0 in. W.G. static pressure. Although the air

delivery dropped to 5 percent below the required minimum at

0.25 in. W.G. static pressure , this performance represents

an increase of 5 percent over previous tests with $-1826-3 fans.

It is believed that adequate air delivery for the Size A condenser

units can be obtained with a few minor adjustments to the air

circulating system, now that an E-1026-3 fan of correct dimension,.,

has been obtained.
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Foliowlng the repair of a leak in the refrigeration circuit

of the teat apparatus, a test of a Size A, Class 1 condenser

at high rate': condition® was begun. With a refrigerant temperature at the condenser inlet of approximately 170 F, the electric

heater installed in the compressor discharge line to control the

discharge gas superheat burned out. It was removed and parts

of the system contaminated by breakdown products vmm cleaned m

necessary. The filter-dryer was replaced. New superheating

heaters, constructed of steel alloy sheath instead, of copper, and

having a watt density leas than half that of the previous heater

were secured and installed.

The system was purged, recharged and again put into operation at the ‘ high rate*' condition. Despite the steps taken to

prevent a recurrence of the failure of the imin evaporator

heaters, one element failed completely and another partially after

less than one hours’ operation. The evaporator section of the

refrigerant side of the calorimeter was removed and rebuilt

completely, using steel alloy sheath heaters of such size that,

operating in still air, the element surfaces do not heat above

235 ?* This was accomplished by operating at less than one half

the manufacturer’s design rate, on which the previous evaporator

was designed.

At the request of the Quartermaster Hesearch and Engineering

Compand, arrangements were made to begin tests of the Class 1,

Size B condensers prior to testing the Size A unite, A Claes 1,

Size B condenser was installed in the system. Thus fan orifice of

a Kramer Trenton Size B condenser «

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removed and remodeled to

conform to the correct bell&outh specifications for testing the

'£-£4-20-4 fan to be used with these condensers . Hone of the eight

£-2420-4 fans on hand conformed to Torrington design specifications

and one was sent to the NBS instrument shop to be reshaped to the

correct blade pitch and depth . Tests of this corrected fan will

be started immediately, The refrigerant circuit of the system

has been checked out after rebuilding of the evaporator section

and appears to perfoim satisfactorily. Tests of the ' ize B

condensers will be started as soon as the proper fan performance

is obtained.
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