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Safflower oi l , with 76.7% linoleic -glycerides, has the highest linoleic purity of any vegetable oil in its •class. Many other unusual proper­ties make it easy to use in formu­lations . . . will give you better processing and a better product. How will it work in your industry? "Write for sa m pi es and information.

SAFETY

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Write today for information:

Industrial Oil Division Pacific Vegetable Oil Corp.

3135 E. 26th St., Los Angeles, Calif.

Controlling Dust in Uranium Plants Radiation complicates ventilation and dust control

in large-scale processing of uranium, but standard indus­trial hygiene engineering principles still apply

General Offices 62 Townsend Street, San Francisco

CHICAGO.—Refining uranium ores and concentrates on a large scale pre­sents many ventilation and dust con­trol problems. Even though radiation encountered necessitates extraordinarily stringent requirements, Catalytic Con­struction Co. approached the problem of designing a plant for AEC with the usual industrial hygiene engineering principles, company's H. I. Miller, Jr., told the 1954 Industrial Health Con­ference held here. Some idea of scope of the project may be gained from fact that cost for ventilation and dust con­trol systems came to about $2 million for installation and 120 engineer-months effort for engineering design. This cost was a small fraction of total cost of plant.

Alpha rays from uranium are ordi­narily harmless, but when particles emitting them are ingested they can be quite harmful. Daughter products in pitchblende give off beta rays which are also relatively harmless. However, gamma ray emitters are also present, and these can be quite dangerous. Product value and toxicity indicate dust-tight equipment so that as little dust as possible will have to be col­lected and rehandled. Buildings in which pitchblende is handled are walled off from rest of plant.

Use of tank car quantities of hydro­fluoric acid does nothing to ease de­sign problems, Miller notes. Most hy­drofluoric is handled in wal led-up areas. Buildings where hydrofluoric is handled are ventilated so that there a r e 15 air changes per hour. This is on assump­tion that all equipment is t ight; for emergency use it is possible t o change air 60 times an hour. I t is readily seen that heat losses of some of these build­ings are small compared to t h a t lost by exhausting air.

As an example of unusual difficul­ties to be solved, Miller told of clean­ing exhaust from a rotary d ryer when feed might contain 5 to 10% dust-size particles. Temperature of exliaust air was ordinarily 400° F. , bu t on occa­sion it might reach 600° F . This hot air could not be sent directly to wet collector bu t must be first cooled to 180° F . A heat exchanger w a s needed to cool the stream. Cyclone separators had to be included in equipment . Be­cause exhaust contained moisture, there was a question of dew point t o be con­sidered and suitable instrumentation had to be provided so that heat ex­changer would not cool air t o o much.

Fog Scrubbers . Dust collection, gas and mist scrubbing, and odor elimina­tion are some applications of fog type

F. A. Thomas, Jr. (left), Georgia Tech, M. W. First, consultant, and Jack Baliff, New York State Department of Labor, tackle dust control in different ways. Thomas told the Industrial Health Conference of design of fog type scrubbers, First evaluated wet fiber filter, while Baliff described water spray system used in a rock-crushing plant

i 932 C H E M I C A L A N D E N G I N E E R I N G N E W S

HIGHEST QUALITY THROUGH 2 , 5 0 0 , 0 0 0 FILTER CHANNELS PER SQ. I N .

A Cëlite Filter Cake is hundreds of times finer than the finest

w i re mesh!

ICE LITE I

AS

TËfimiim Λ

Celite Filtration assures perfect clarity— adds eye appeal and buy appeal to food products

T o GIVE foods and beverages that extra quality which results in more sales appeal, leading processors de­pend o n Celite Filtration. The Celite method provides perfect clarity at high production rates.

Celite Filtration is efficient. It re­moves even thefinest suspended solids. Moreover, Celite Filtration is eco­nomical. It may be used with any type of conventional filter, it is almost

automatic, and only unskilled labor is required for routine operation.

And Celite Filtration is flexible. T o in eet your specific requirements, Celite comes in nine standard grades o f microscopically control led particle size. The right balance between degree of clarity and rate of flow may be easily controlled. You can obtain perfect clarity in food products—highest pur­ity in antibiotics—complete removal

of insoluble impurities from water, petroleum, chemicals, dry cleaning solvents and many other liquids.

A Johns-Manville Celite Filtration Engineer will gladly discuss the ad­vantages and use of Celite in your product or production process. For his services, without obligation, write Johns-Manville, Box 60, N e w York 16, Ν. Υ. In Canada, 199 Bay St., Toronto 1, Ontario.

JOHNS-MANVJLLt

aful Johns-Mcmville C E L I T E P K . O O U C T 8

INDUSTRY'S STANDARD FOR FINEST FILTRATION

V O L U M E 3 2, N O . 1 9 » » . M A Y 1 0 , 1 9 5 4 1933

SAFETY-

scrubbers. Fog (generated either by passing scrubbing medium under high pressure through small orifices, or by introducing it under low pressure through jets into a high velocity air stream) comes in contact with gas stream being cleaned and particles or other impurities are removed. Present thinking, according to F. A. Thomas, Jr., Georgia Tech, is that impaction, wetting, and centrifugal action are probably most important mechanisms involved, although not enough is yet known to determine relative impor­tance of these. Small particles (less than 10 microns) are difficult to sepa­rate from a gas stream merely by their inertia. In fog scrubbers, these par­ticles combine with other particles or with drops of scrubbing medium to give a n e w particle having enough inertia to be centrifuged from stream.

For maximum impaction rate, fog particles should have a size distribu­tion comparable with that of particular matter being removed. If spray drops are large, particles tend to flow around the drop. In removing gases of re­acting chemicals from polluted air streams, fog scrubbers function by pro­viding a large surface of scrubbing medium. Action might be primarily a surface phenomenon, but not entirely

so, Thomas says. Fact that fog scrub­bing has been effective with oil mists indicates possible electrostatic effects.

Entrainment of scrubbing med ium in discharge air stream decreases wi th increasing pressures and air flow rates for moderate and high fog pressures. It increases to a maximum arid then de­creases with increasing air flow rates for low and marginal fog pressure. En­trainment can be reduced or eliminated by using high pressure scrubbing sec­tion prior to discharge of air.

Fume Hoods . By measuring face velocity and observing smoke patterns in lab fume hoods with varying face velocities, cross draft velocities, thermal loadings, slot openings, entrance shapes, and other factors, H. F. Schulte, Los Alamos Scientific Laboratory, evaluated a number of hoods. H e found that an average face velocity of 100 ft. per minute and a minimum velocity of 80 ft. per minute at any point on hood face is necessary w h e n moderately toxic materials are handled .

Not only should attention b e paid to ordinary safety considerations w h e n locating a hood in the lab, but hood should b e placed so as to avoid cross drafts from air inlets and other sources of air disturbance. Schulte finds that w h e n velocity of cross current air

COWLES SILICATES FOR COMPOUNDING

when it's DRYMET

Sixty pounds of DRYMET—anhydrous sodium metasilicate—will do the same amount of work asonehundred pounds of pentahydrate sodium metasilicate! You get approx imate ly two thirds more chemical value in DRYMET, yet the price is less than one fourth higher at the producing factory!

WRITE FOR DRYMET File Folder containing complete technical Information.

Ï *R«s. U. S. Pal. Off.

equals or exceeds face velo-city, seri­ous disturbances result. H e aJso points out that a radiator loc-ated near a hood loses almost all of i t s h_eat to ex­haust.

Experiments with hot plates and Meeker burners d i d n o t adversely affect hood perfonrt ance as long as velocity w a s 10O ft. p>er m i n u t e . Doors do not contribute much t o function of hoods except US safety precautions. Corner posts create disturbances a s do sinks and other «depressions. 3Front side of a sink should be a t least 63 in. back from front of hood.

• Combustible gas d e t e c t o r s for in­stallation in Class I, Group JD hazard­ous locations t o analyze a n d warn of dangerous concentrations o£ combus­tible gas have been listed for the first time by Underwriters' Labs, according to Mine Safety Appliances, manufac­turers of the instruments. Company says its instruments have also re­ceived approval from Associated Fac­tory Mutual F i r e Lalbs,

• An explosion—proof case £or electric timers provides conrjplete protection in hazardous locations, says Zenith E l e c ­tric. Sett ing k n o b is connected directly to the switch - o p eratxng c a m ; since the unit does not set: throvugh .a cLiitch, posi­tive switch is provided. A l l energy required to operate *:he s w i t e h is built up by t h e ma.nuall-y settirLg pointer, thereby rel ieving motor ariol clutch of drag. S 1

• A o n e - ov two-ntcin f ire truck de­veloped b y Kalamazoo Mfg. Co. is said to be maneuverab le through narrow aisles and standard doors. W i t h a s p e e d of 15 miles per hour, it c a n g e t to a fire quickly. It c a n be e q u i p p e d to carry complete high pressure f o g systems, 210 gal. of water, 100 ft. of booster hose, rotary piamp, foam concentrate, various extinguishers, an<i other auxil­iary equipment- S 2

• A fire-retard «ant paint- s a i d to com­bine superior flam«e resistance with durability, -wasbability, a n d attractive­ness is available from Glidden Co. Called D u o - T e x , it is a res£n-base, in­tumescent t y p e intexior finish that im­mediately swe l l s anol chars on contact with flame to p r o v i d e a firm, insulating blanket of non comb Tistible ash . Avai l ­able in 12 pastel colors, it bears the label of Underwritexs' L a b s , according to Glidden. It can b>e appl ied by brush or spray. S 3

COWLES CHEMICAL C O M P A N Y 7 0 1 6 Euclid A v e n u e Cleveland 3, Ohio

For fur ther infoermatSon on any keyed i tem men-toned here, see

coupon on page 1944

1934 C H E M I C A L A N D E N G I N E E R I N G N E W S