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NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT

0703-30-3881

NBS REPORT

6260

January 6, 1959

Air Flow Measurements in a Laboratory Fume Hood,

Fisher Scientific Co,, Type 17-105

t$7

William F* Goddard

t

Report to

Ilaval Security Agency

Washington, D. C.

IMPORTANT NOT (Cl

NATIONAL BUREAU Of ST

Intended for use within the

to additional evaluation and

listing of this Report, either the Office of the Director, Ni however, by the Government

to reproduce additional coph

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST)

on October 9, 201 5.

progress accounting document!

ormally published It Is subjected

?, reproduction, or open-ilt^tyce

sslon Is obtained In writing Such permission Is not needed,

1 prepared If that agency wlshe* <NBS>

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
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Report on

Air Flow : leasuraments in a ..aboratory Fume Hood,

Fisher Scientifie Co., Type 17-105

for

The Taval Security Agency

(tin: ferr. George A. Smith)

1. Introduction

In accordance with the request of av George A. Smith, Gaval Security

Agency, on ieeamher 3» 195B, air measurement tests were wade on one of two

identical laboratory hoods, Fisher Scientific Co., Type 17-105. These measurements were made on December 10, 195^* to ascertain the velocity through

these fuse hoods with the front window in open and closed positions and to

also ascertain the flow through the hoods while operating thesa at a static

pressure (outlet) of l/4-in, water gauge , as specified by the manufacturer.

It was requested by the Haval Security Agency that a vane type anemometer be used for these xasasuretsents.

2• d escription of the lest Specimen

lisa fume hood superstructure, inside dimensions 46 in. x Z) in, x 36

to 41 in., consisted of a steel frame with side and roof panels resting

on a steel base and laboratory type top. A vertical baffle was situated

2 in, out from the rear wall, beginning 10 i/2 in. up from the table top

and extending 23 l/2 in. upwards, at which height it met an overhead

adjustable type baffle positioned at an angle of 45 degrees with the back

wall and ceiling. There were adjustable dampers at both the upper and

lower edges of this inclined baffle. The plenum thus formed by the vertical and inclined baffles m.9 connected to the exhaust system by an adapter

measuring 16 in. x 4 in. x 12 1/2 in.

A motor-blower utility set located on top of the hood and connected to

the adapter through a 7-in. diameter duct provided the air circulation

through the hood. The motor-blower assembly, as specified in serican 'flower

Bulletin Ho. 8314, consisted of a l/3 H.P. , 1725 BPM, 5°-B0 cycles motor

driving a blower rated ty the manufacturer at 655 CFi at i/4 in. S.P.

A movable window panel at the front of tiie cabinet provided access to

the hood. The face dimensions of the window opening in an open position

were 40 l/4 in. x 30 1/2 in.; in a ''closed''1 position, 40 1/4 in. x 1Jo in.

The attached side view sketch shows the arrangement and principal dimensions of the baffles inside the hood, and the front view sketch shows the

dimensions of the window opening and the opening to which the exhaust

blower was attaelsed.
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3 Test Procedure

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i-slth the blower naming continuously, and restricted at the outlet to

produce a l/4~ln. 8.P* on the discharge side, a 4-in. calibrated vane type

anemometer was used to make four air-velocity traverses, as follows;

(1) In a vertical plan© defined by the opening existing when the window was in a fully raised position, this was an area of 40 l/4 in. x

30 l/Z in*

(2) In a vertical plane defined by the opening existing when the window was raised 4 5/8 in. from the table top. (this wag the smallest vertical

dimension in which the mne type anemometer could be used.) The area of

the traverse was 40 1/4 in. x 4 5/8 in.

(3) In a vertical plane 9 in. from the back wall and parallel to it5 from the table top to 30 in. above the table top with the front window

fully open. Travers© area was 46 in. x 30 in.

(4) In a vertical plane 9 id* frests the back wall and parallel to it

for a height of 7 in. from the table top. This afforded an area for

traverse measuring **6 in. x 7 in. The front window was closed for this

measurement

.

Each traverse was made twice—once with the darepers open and a second

time with the dampers closed. In addition to these, there were some measurements made -with the front and then the back dampers of th© inclined

baffL© open, in turn.

A traverse in the 46 in. x 10 l/2 in. opening under the vertical baffle

could not be mad© because of the presence of fittings and a drain in this

space.

4. Test Results

The traverse made with tiie access window open 4 5/8 in. showed an average velocity of 53

5

feet/islnate in the opening corresponding to a total air

flow rate of 690 cu ft/rain. It would be safe to assume that the air flow

rate with the window fully open would be equal to or greater than 690 cu ft/rain

Thus, the equipment meets th© minimum air flow requirement of 500 cu ft/min

reported to be incorporated in th© purchase specification

.

hen th© access window was fully open the air flow would not turn the

vane anemometer steadily in any part of the opening. Calibrations of the

instrument at the National Bureau of Standards indicated that a velocity
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