NATIONAL BUREAU OF STANDARDS REPORT

3171

GAYLORD CLEARAIR VENTILATOR

by

Carl W. Coblentz

Paul R. Achenbach

Report to

Bureau of Ships

Department of the Navy

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
U. S. DEPARTMENT OF COMMERCE

Sinclair Weeks, Secretary NATIONAL BUREAU OF STANDARDS

A. V. Astin, Director

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NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT NBS

X0O3“2O»4$35 March 15, 1954

GAYLORD CLEARAIR VENTILATOR

by

Carl W. Coblentz

Paul R. Achenbach

Heating and Air Conditioning Section

Building Technology Division

to

Bureau of Ships

Department of the Navy

<NBS>

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

The publication, rep

unless permission Is < 25.D.C. Such pern

cal ly prepared If th;

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST)

on October 9, 2015.

n part, Is prohibited

ndards, Washington

ort has been speclflrort for Its own use,

REPORT

3171

GAYLORD CLEARAIR VENTILATOR

by

Carl W. Coblentz and Paul R. Achenbach

Abstract

As a part of the study of methods for testing and

rating grease filters undertaken for the Bureau

of Ships performance tests were made of a specimen

Gaylord Clearair Ventilator manufactured by Gaylord

Industries. This device depended primarily on centridugal force to remove droplets of grease from

the effluentt air stream over a cooking range. The

tests indicated that the efficiency of the Gaylord

ventilator ranged from about 70$ to 90$ for a range

of loading rates from 1 to 50 grams of grease per

hour with the efficiency values increasing as the

loading rate was increased. A thermostatic firedetector in the grease extractor operating on the

rate-of-rise of temperature and a selected constant

temperature closed the inlet damper to the extractor

and stopped the exhaust blower automatically if a

fire occurred on the range top. Limited tests indicated that this device would prevent ignition of

accumulated grease in the extractor or exhaust ducts.

The static pressure drop through the ventilator was

higher than that for impingement filters at the

rated air flow rate and it would probably be necessary to remove grease accumulations by wiping operations for the specimen tested.

I. INTRODUCTION

As a part of the study of testing and rating methods for

grease filters being conducted at the National Bureau of

Standards for the Bureau of Ships, performance tests were made

of a specimen Gaylord Clearair Ventilator manufactured by the

Gaylord Industries, Portland, Oregon. The Gaylord ventilator

is a sheet metal device that is mounted at the rear side of

the cooking surface. It is designed to remove the grease from

the air drawn over the stove surface by impingement and centrifugal force.
2

The conventional method for removing grease from the effluent' air over cooking surfaces is to place impingement type

filters, usually with a metallic filtering media, at the entrance to the exhaust ducts over the range. The grease, dust,

and lint accumulate on these filters necessitating that they

be cleaned at intervals. This type filter can be re-used a number of times after cleaning, but eventually must be replaced

because of clogging or damage to the filter media. The Gaylord

ventilator operates on a different principle in that no filtering media is employed and no replacement elements are required.

Tests were made to evaluate the efficiency of the Gaylord

Clearair Ventilator as a grease trap for a range of air velocities

and a range of grease content in the effluent air. The pressure

loss in the device was measured for a range of air flow rates

and tests were made of the fire detector incorporated in the

ventilator.

II. DESCRIPTION OF TEST SPECIMEN

Fig. 1 shows a schematic drawing of the Gaylord ventilator

which was designed for mounting at the back side of the cooking

surfaces. This sytem does not use any filters. The grease and

lint reach the extractor chamber through the ventilator throat

and are separated from the air by impingement and centrifugal

action. The ventilator throat $as 2 inches wide and extended

the full length of the apparatus. The grease and lint are collected on the wells of the extractor chamber, on the baffles

and on the extractor plate . Some portion of the deposits flowed

down into the grease trough. The extractor plate was hinged

and could be operated either manually or automatically by a

thermostat which served as a fire detector. The closing of the

fire trap would shut off the blower motor automatically. A,

transition piece above the extractor chamber served as a /plenum

for the exhaust duct system. The manual operating lever of the

thermostatic fire detector can be seen, above the shelf of the

ventilator in Fig. 2.

III. TEST APPARATUS AND PROCEDURE

A simulated cooking range was built with a 3x4 ft cooking

surface on which the ventilator was mounted. The l/4-inch thick

top' plate of hot-rolled steel was heated with a gas burner of

approximately 70,000 BTU/hr capacity,. The experimental cooking

range and gas burner, the specimen ventilator, and the exhaust

duct at the ventilator outlet can be seen in Fig. 2. The ventilator was connected to an exhaust blower driven by a variable

speed motor allowing the air flow rate through the ventilator

to be varied in the range from 900 CFM to 1500 CFM.
- 3 -

A sampling tube containing glass wool was installed in

the exhaust adaoter above the transition piece. It had been

previously determined that this kind of sampler could be considered an absolute filter, for all practical purposes. The

air flow through this sampler was measured with a gas meter

and the value of the air volume indicated on the gas meter

during the test was corrected for the vacuum observed downstream of the sampler. If L was the volume of air drawn

through the sampler as indicated by the gas meter and pra was the pressure difference between the atmosphere and the

g-as meter inlet, in cm Hg, then the actual volume of air

drawn through the sampler at atmospheric pressure was:

Vs = 76 ~ Pm x

: V^

76

The amount of grease collected in the extractor was determined by wiping the extractor chamber, the trough and

the fire damper with soft paper tissue and determining the

weight increase of these tissues to one hundredth of a gram.

By multiplying the weight increase of the sampler by the ratio

of the total air drawn through the ventilator to the air volume

drawn through the sampler the amount of grease that passed

through the extractor could be determined for each test.

Wg = Wo x \

V s Where Wg = weight of grease passing through ventilator , grams

W5 = weight increase of sampler, grams

Vv = air drawn through ventilator, Cu. Ft.

Vs = air drawn through sampler, Cu. Ft.

The efficiency of the ventilator, then, was the ratio of

the weight of the grease collected in the extractor to the total

amount of grease introduced into the grease trap, i.e. the grease

that escaped through the ventilator plus that retained in the

extractor.

E

Wy

Wy + Wg x 100

Where E = efficiency, percent

Wy = weight of grease retained in ventilator, grams

Wg = weight of grease that • passed through ventilator,

grams
- 4

-

Another efficiency value called the "apparent efficiency"

was determined which did not credit the ventilator for the

amount of grease splattered on the floor and that evaporated

from the hot cooking surface. The "apparent efficiency" is

defined as the ratio of the grease collected in the ventilator

during the test to the difference between the total grease dissipated and the grease wiped from the endplates, backplate, and

shelf and from the cooking surface.

Where = apparent efficiency, %

Wv = weight of grease retained in ventilator, grams

W«j. = total grease dissipated, grams

WQ

= grease wiped from end plates, backplate, shelf,

and cooking surface, grams

The amount of grease splattered on the cooking surface and

evaporated could never be fully accounted for. Therefore, it

was expected that the apparent efficiency would always be lower

than the actual efficiency, the difference depending on the intensity of splattering.

Three different methods were used for the generation of

grease vapor or mist.

1. Fig. 2 shows a photograph of two baking trays, 9 x 15 in,

and 2 in. high, filled with grease approximately 1/2 in.

and heated on the cooking surface. A loop of 1/4 in. copper

tubing with 0.020 in. holes was placed on the bottom of

the trays through which air was blown to accelerate the

volatilization of the grease. At a grease temperature of

approximately 320°F a total of 10 grams could be volatilized

per hour from two grease trays and it was found that only

about one-third of this amount reached the ventilator throat,

two-thirds being lost by splattering. Since grease dissipation rates as high as 90 g/hr had been observed in actual

operation in the galley of the U.S.S. Tarawa it appeared

that the results to be obtained with this apparatus would

be indicative of only a limited part of the operating conditions likely to be encountered.

2. Vats 15 x 15 in. and 8 in. high were also tried and Fig. 3

shows how two such vats were located on the cooking surface.

The loading rate obtained with this method was higher than

that observed with the shallower trays and the rate of

splattering was lower. However, it was impossible to
reach a grease dissipation rate approaching 90 g/hr

so this method was not used during any of the tests

which have been employed for the evaluation of the

specimen ventilator.

3. A small paint sprayer was then used as shorn in Fig. 4.

It was mounted at the left front corner of the cooking

surface and the grease, heated to about 200°F, was

sprayed diagonailv across the cooking surface. The

grease particles, atomized by the paint sprayer, were

examined on a microscopic slide and it appeared that

they were similar in size to those collected on slides

in actual cooking on board the U.S.S. Tarawa. With a continuous spray of grease into the air stream the

grease dissipation rate was regulated to values in the

range from 20 to 60 g per hour. By directing the spray

cone towards the separator throat the amount of splattering was reduced considerably and this method was used

for the majority of the tests made.

At the beginning, tests were made over a six hour period,

but the length" of test was later reduced to three hourfe.

The following measurements were made during each test:

1. The total amount of grease dispersed was determined as

the difference of the weight of the grease-containing

vessels before and after each test.

2. The amount of grease collected on the walls of the ventilator facing the cooking surface and splattered on the

cooking surface by wiping off these surfaces with soft

paper tissues and determining the weight increase of

these tissues,

3, The amount of grease collected in the ventilator was likewise obtained by cleaning the extractor chamber, the

trough and the fire damper and determining the weight

increase of the paper tissues,

4, The air flow rate through the ventilator was observed by

means of an orifice flow meter which had been previously

used for the grease filter test apparatus. As the straight

length of pipe approaching the orifice had to be shortened

for this installation the flow coefficients quoted in the

A.S.M.E. Research Publication on Fluid Meters were no

longer applicable. The orifice meter was, therefore,

empirically calibrated for the desired flow rates by means

of a Pitot tube.
- 6 -

5. The pressure drop across the ventilator was observed

on an inclined manometer as the difference between

the static pressure in the transition piece and atmospheric pressure.

6. The total air flow through the sampler tube was observed

with a gas meter. The flow rate was adjusted to approximate the desired value by means of an orifice flow meter

and maintained at a steady rate for each test. The determination of the actual air flow rate was considered

to be more accurately measured with a calibrated gas

meter than with an orifice flow meter because the air

pressure in the transition piece changed with the air

flow rate of the ventilator. This would have made it

necessary to calibrate the orifice flow meter for each

ventilator air flow rate.

7. The amount of grease retained in the sampler tube was

determined as the weight change of the sampler during

the test. The samplers were dried in a desiccator for

at least three days before each weighing and each weight

was determined to ±0.1 milligram.

The pressure drop across the sampler tube was determined

with an U-tube manometer as the difference of the static

pressure at the outlet of the sampler and that in the

transition piece.

The effluent air temperature was maintained at 105°F±2°F

at a point 1 ft above the ventilator during all tests by regulating the temperature of the stove plate. The temperature of the

grease was also observed but it was found that variations in

grease temperature caused no noticeable effect on the operation

of the apparatus. All observations were made very 30 minutes.

IV. TEST RESULTS

From the observed data the following values were computed:

1. The corrected air flow rate through the sampler was calculated as described earlier.

2. The computation of the amount of grease that escaped through

the ventilator has also been described.

3. The weight of grease lost by splattering was the difference

between the total amount of grease dissipated and the grease

that escaped through the ventilator plus the grease retained

in the extractor and on the walls facing the cooking surface. The grease lost by splattering was also calculated

in -percent of the amount of grease dispersed during each

test

.
- 7

-

4. The loading rate of the ventilator was the weight of

grease wiped from the inside of the extractor divided

hX the duration of the test.

5. The computation of the actual and the apparent efficiencies was explained earlier in this report.

Table 1 is a summary of the observed and computed results

from 26 tests which were considered to be indicative of the

performance of the apparatus.

The actual efficiency was plotted against the loading

rate in Fig. 5 and a curve of the least mean distances was

drawn. The scattering of the different points of observation is attributed to the limited accuracy possible in this

kind of tests and to some variations in the air flow through

both the ventilator and the sampler. The weight increase of

the sampler tube was as low as 4.6 mg during one test and a cumulative error of only 0.2 mg made in weighting before and

after the test could cause a difference of approximately 9

$

in the calculated weight of the grease that escaped through

the ventilator. The magnitude of these deviations was of a

smaller order for these tests than during the tests of

impingement type filters.

The changes in the air flow rate through the ventilator

ranging from 900 CFM to 1500 CFM did not cause any noticeable

change of the efficiency as indicated by the fact that all the

observed values of efficiency fall into the same pattern in

Fig. 5.

The negative values of "grease lost by splattering” in

four tests shows that the total amount of grease accounted

for as wiped off the inside and outside wells of the ventilator plus the amount calculated as escaped through the ventilator was larger than the weight of grease dispersed during

that test. This discrepancy ranged from 0.6g to 2.7g or

0.5$ to 2.0$ of the total grease dispersed and was caused by

observation errors or through unequal cleaning of the extractor

after each test.

The average percentage of grease lost by splattering was

33.3$ in tests where trays were used for the grease dispersion

and only 10.1$ when the atomizer was used. The differences

between the apparent efficiency and the actual efficiency were

correspondingly smaller in those tests where the atomizer was

used.
- S -

Fig. 6 shows a graph of the pressure drop across the

ventilator plotted against the air flow rate and reveals

an almost linear increase of the pressure drop from 0.6 in.

W. G. at 900 CFM to 1.4 in. W.G. at 1500 CFM air flow.

The apparatus was operated approximately 250 hrs and

only a very slight film of grease could be noticed in the

transition piece just above the separator after this time.

A test was also conducted on the automatic operation of

the fire trap. The sensing bulb of the fire detector was installed in the transition and, in case of a fire closed an

electric circuit to a relay that released a trigger and shut

the fire trap. Thus the damper interrupted the flames entering the extractor and prevented the grease accumulated there

and in the ducts from igniting. The release of this trigger

mechanically opened a switch which cut off the exhaust blower

circuit. The operation of the fire trap could also be accomplished manually with the same effect on the exhaust blower.

By manually opening the fire trap the blower switch was closed

again.

The thermostat was a

Tt Fenwall rate-of-rise and constanttemperature fire detector" and was set for 350°F. In a test

preliminary to its installation in the ventilator it was immersed in a grease bath that was heated up at a rate of approximately 5°F per minute and it was observed that the contacts closed at 347°F.

Two tests were made with different intensities of stove

fires in which the temperature rise of the effluent air was

observed adjacent to the thermostat and the time determined

for closing the fire trap. Table 2 shows the results obtained

in these tests.

Table 2

Tests of Fire Detector

Air Temperature Time Required Rate of Air

Start End

°F

for Closing Trap

Min

Rise

°F/Min

Test 1 112 265 5 31

Test 2 106 305 2 100
- 9 -

It might have been expected that at the higher rate of

temperature rise the trap would close at a lower temperature.

However, due to the mass of the thermostat it is apparent

that its temperature lagged behind the ambient air temperature.

Fig. 7 shows the grease fires used to test the operation

of the fire detection device.

V. DISCUSSION AND CONCLUSION

The test results showed that the filtering efficiency of

the Gaylord ventilator was equal or slightly better than the

average observed on impingement type filters for the range of

loading rates from 1 to 50 gv/hr.

A 1000 CFM air flow rate was recommended for the 4 ft.

long test specimen. The air flow rate through a 20x20 in.

impingement filter at 400 ft/min face velocity is #95 CFM.

Since it had been observed in the galley of the U.S.S. Tarawa

that one such filter was installed for approximately each 4 ft

of cooking frontage it is believed that the ventilator will

supply ample ventilation.

The pressure drop across the ventilator at an air flow

rate of 1000 CFM was 0.77 in. W.G. which is about 10 times as

high as that of a clean impingement type filter. However,

the pressure drop of the Gaylord ventilator did not increase

with the grease load accumulated in the extractor which assured

equal ventilation of the galley at all times, whereas the

ventilation always decreased as the impingement filters loaded

up or became clogged up.

The Inherent advantage of the Gaylord ventilator is the

absence of expendable components, as the impingement filters

must be considered to be. Since the ventilator replaces the

conventional hood and can be installed along the walls as well

as between double-row or island-style ccokin^* facilities there

does not appear to be any difficulty with regard to space requirement and the weight of the ventilator is less than that

of a conventional hood. The connection of the exhaust ducts

to the ventilator can be accomplished in several different ways.

The grease collected in the separator of the test specimen

had to be wiped out with a cleaning rag or paper tissue after

removal of the clean-out panel at the back. The clean-out

panel can be arranged so that the trough and the rest of the

separator are accessible either from the rear or from the front

of the cooking surface. For shipboard use only accessibility

from the cooking surface would be acceptable.
10

The fact that the grease retained in the extractor of the

test specimen had to be wiped out makes it unsuited. to Navyuse in its present form.

It is believed that the model tested could be modified and

a means provided for continuous removal of the grease collected

in the separator and trough but this was not attempted during

the tests.
Item 16 17 18 19 20 21

1

Observed Va

Mode of gre A A A A A

h

ii. Durs t ion of 3.0 3.0 3.0 3.0 3.0 3.<

Total gre as 119.9 113.7 13s. 5 99.3 71.6 166.

Grease wipe 16.7 15.7 15.3 6.6 6.2 17. i Grease reta 76.3 70.

s

108.4 67.9 54.2 131.I

Airflow thr 1500 1500 1500 1000 1000 100c

Pressure dr i.4i 1.42 1.37 0.76 0.77 0.71

Air flow th 5**l 5**9 54s 526 569 535

Grease reta 25.2 23.0 31.4 23.8 20.0 50.4

pressure dr 10.7 s.o S.7 8.0 6.8 7.8

Calculated

Sampler air 2.5s 2.73 2.69 2.61 2.93 2.68

Grease esca 14.63 12.63 17.50 9.13 6.83 18.80

Grease lost 12.3 14.6 -2.7 15.7 4.4 - 0.9

Grease lost 10.3 12. S -2.0 15.

s

6.1 - 0.5

Loading rat 25.4 23.6 36.1 22.6 18.1 43.8

Apparent ei 73.9 72.3 87.

S

73.2 82.8 87.9

Actual effi 84.0 84.3 86.0 88.2 88.8 87.4

VO

C-'i

vjl

'X>
TABLE 1

SUMMARY OF TEST RESULTS

Gaylord Clearair Ventilator

Test Ho.

Iiem 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

Observed Values

Mode of grease dispersion * A A A T T A A T T T T T A A A A A A A A A A A A A A

Duration of test hrs 6.0 5.0 6.5 7.0 7.0 7.0 7.0 3.5 3.5 3.o 3.5 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 6.0 1.25 3.17 3.0 3.0

Total grease dissioated € 384.3 so.o 235.0 23 62 107.3 l4l,4 48 38 24 25 4l 111.2 153.3 109.7 119.9 113.7 138.5 99.3 71.6 166.9 102.6 44.3 70.9 119.

70.6

Grease wiped from walls g 29.0 4.7 15.5 5.9 16.2 6.2 7.5 25.2 18.5 6.7 9.2 9.5 13.8 37.5 13.4 16.7 15.7 15.3 6.6 6.2 17.6 9.3 3.1 11.1 8.6 1.0

Grease retained in ventilator g 317.1 51.8 165.9 11.9 15.6 62.2 94.5 5.7 8.5 4.5 4.2 8.6 54.2 02.4 68.9 76.3 70.8 108.4 67.9 54.2 131.4 71.5 26.5 49.6 80.1 54.4

Airflow through ventilator CFM 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1295 1295 1500 1500 1500 1000 1000 1000 1000 1000 1000 900 900

Pressure drot> across ventilator in.VT.G,, - - - - - 0.75 0.76 o.75 0.77 0.80 0.77 0.77 0.77 1.17 1.18 1.4l 1.42 !.37 0.76 0.77 0.77 0.77 0.77 0.77 0.60 0.60

Air flow through gas meter cu.ft. 1055 s44 1133 1204 1191 1248 1228 634 613 529 634 525 536 539 551

541 549 548 526 569 53?

50.4

1149 237 580 533 542

Grease retained in sampler mg 105. s 33.2 94.2 8.8 16.2 54.2 75.4 4.6 6.4 5.6 4.2 10.4 19.8 21.4 19.6 25.2 23.0 31.4 23.8 20.0 39.2 14.5 21.0 36.1 36.2

Pressure drop across sampler cm Hg 7.7 5.1 5.9 6.6 7.2 10.1 6.8 7.7 7.7 5.5 7.7 5.4 6.2 7.3 8.8 10.7 8.0 8.7 8.0 6.8 7.8 5.8 10.4** 8.2 5.5 5.6

Calculated Values

Sampler air flov, corrected CFM 2.63 2.63 2.68 2. 6l 2.53 2.57 2.66 2.71 2.62 2.73 2.72 2.72 2.73 2.70 2.71 2.58 2.73 2.69 2.61 2.93 2.68 2.94 2.74 2.72 2.75 2.75

Grease escaped throu^i ventilator g 40.2 12.6 35.1 3.37 6.4o 21.1 28.3 1.70 2.44 2.05 1.55 3.82 7.24 10.26 9.36 14.63 12.63 17.50 9.13 6.83 18.80 13.33 5.29 7.72 11.82 9.90

Grease lost by splattering g - 2.0 10.9 18.1.8 23.8 17.7 11.2 15.4 8.6 10.8 10.1 19.1 36.0 13.1 18.1 12.3 i4,

-2.7 15.7 4.4 - 0.9 8.0 9.4 2.5 I8.9 -0.6

Grease lost by splattering 1

" 0.5 13.6 7.9 7.8 38.4 16.5 7.9 32.1 22.6 45.0 4o.4 46.5 32.4 s.5 16.5 12.8 -2.0 15.8 6.1 -0.5 7.8 21.2 3.5 15.8 -0.8

Loading rate of ventilator g/l*r 52.9 10.4 25.5 1.7 2.2 8.9 13.5 1.6 2.4 1.5 1.2 2.9 18.1 30.8 23.0 25.4 23.6 36.1 22.6 18.1 43.S 11.9 21.2 15.65 26.7 18.1

Apparent efficiency * S3.

6s.

75.6 69.8 34.0 61.5 70.6 25.0 43.3 25.8 26.7 27.1 55.6 79.8 71.6

ll9 72-3 87.S 73.2 82.8 87.9 77.0 64.3 82.7 72.3 85.2

Actual efficiency % S3.

80.4 82.6 78.0 70.8 74.8 77.0 77.1 77.5 68.5 73.2 69.4 88.2 90.0 88.1 s4.o 84.8 86.0 88.2 88.8 87.4 s4.4 83.4 86.6 87.1 84.5

* Mode of grease dispersion

A = atomizer (spray gun)

T = 2 trays, 9" x 15” x 2"

** Glass filter paper was used instead of sailing tube
16 17 18 19 20 21 22 23 24 25 26

A A A A A A A A A A A

3.0 3.0 3.0 3.0 3.0 3.0 6.0 1.25 3.17 3.0 3.0

119.9 113.7 138.5 99.3 71.6 166.9 102.6 44.3 70.9 119.4 70.6

16.7 15.7 15.3 6.6 6.2 17.6 9.3 3.1 11.1 8.6 7.0

76.3 70.8 108.4 67.9 54.2 131.4 71.5 26.5 49.6 80.1 54.4

1500 1500 1500 1000 1000 1000 1000 1000 1000 900 900

l.4i 1.42 1.37 0.76 0.77 0.77 0.77 0.77 0.77 0.60 0.60

541 549 54s 526 569 53? 1149 237 580 533 542

25.2 23.0 31.4 23.8 20.0 50.4 39.2 14.5 21.0 36.1 30.2

10.7 8.0 8.7 8.0 6.8 7.8 5.8 io.4»* 8.2 5.5 5.6

2.58 2.73 2.69 2.61 2.93 2.68 2.94 2.74 2.72 2.75 2.75

14.63 12.63 17.50 9.13 6.83 18.80 13.33 5.29 7.72 11.82 9.90

12.3 14.6 -2.7 15.7 4.4 - 0.9 8.0 9.4 2.5 18.9 -0.6

10.3 12.8 -2.0 15.

8

6.1 - 0.5 7.3 21.2 3-5 15.

8

-0.8

25.4 23.6 36.1 22.6 18.1 43. s 11.9 21.2 15.65 26.7 18.1

73.9 72.3 87.8 73.2 82.8 37.9 77.0 64.3 82.7 72.3 85.2

s4.o 84.

s

86.0 88.2 88.8 87.4 S4.4 83.4 86.6 87.1 84.5
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GAYLORD VENTILATOR

SCHEMATIC

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GAYLORD VENTILATOR



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 ($1.25) and its Supplement ($0.75), available from the Superintendent of Documents, 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.