Document RE3V6ZXmzDQyeQZy0Y8Le6La

FILE NAME: American Cyanamid (AMCY) DATE: 1953 Mar DOC#: AMCY015 DOCUMENT DESCRIPTION: Published Article from American Industrial Hygiene Quarterly v-jt1 iw , "">* ,Y-ri>< A -4/2 - P N i X X L . c ^ vycIj -Adtfa- - v'^~ YY\0-vA/' )^ s'li m : 2-V A Simple Device for Air Analysis J 5. G i S C L A R D , j H . R O O K , W . V. A N D R E S E N and W . R. B R A D LE Y inc'usfr.ii Hyaien e Section, Ceni-ai Medical Deport mem American Cvan-i.--ic Company, Now (ore, Now York CONVENTIONAL sampling and methods analysis of of atmospheric gases usually consist of scrubbing the air to be tested through a selective absorbing liquid for a determined period of time and then analyz ing the solution. A variation of this procedure lies in an "air titration" method whereby the air to be tested is drawn through a selective ab sorbing solution containing an indicator until a color change takes place. By noting the volume of air required to effect this color change a calculation can be made on the spot as to the concentration of gas present. Such a procedure has been de scribed for the determination of sulfur di oxide in the atmosphere.1 From the industrial hygiene standpoint we have found that, depending on con ditions, such "or, the spot" information is often preferable to longer period sampling for the following reasons: (It In con trast to the average values obtained by tong period sampling, peak co n cen trations associated with haz- - ardous conditions are noted at once. (2! Where extensive cov erage is important, Y p- more r e p r e s e n t a t i v e analyses can be made in a given period of time. 13 T Data is ob tainable where lab oratory facilities are not readily accessible. (4) A minimum of equipment is required. J}U~, E x p erien ci ng the need for a versatile, portable device which would expedite such sampling, we have de veloped and used for a number of years a simple apparatus which might be described as a spot sampler. The success which we have had in using the device has prompted us to describe it heie for the benefit of those who might be seeking such methods and types of appa ratus. The device ready for use is shown in Fig. 1. It consists of a 100 cc syringe mounted on a 2Vi" x 12" x Ei" plywood board by means of bronze clips. A small hole is drilled 2" from the end of the board to accommodate a T tube of any convenient size with one arm bent as shown and con nected to the tip of the syringe by means of rubber tubing. The back panel board consists of a piece of plywood 4" x 5" x U " with a lyV' x 114" x U" base nailed at the bottom. A small bole is drilled through the base and the plywood board to take a small bolt and wing nut which secures and holds the panel upright as shown. Two side arm test tubes are mounted on the panel C- -' . Iri'fJ -tp Z't-Y'-vVila'eA" ,-r- R q. I. 'll * 4{b j' H f EXHIBIT *eio Si Marek, 1053 by means of metal clips. The inlets of the test tube consist of a piece of 5 mm O.D. pyrex tubing 6V2" long drawn to a 2 mm opening at the bottom and inserted through a Ho. 2 one-hole rubber stopper. In operation, 10 ml of the absorbing liquid is placed in the tube and, holding the device in the left hand, the left index finger is placed over the opening of the T Tube. The plunger is then pulled at a rate of about 100 cc per 30 seconds until the 100 cc mark is reached. The index finger is re moved and the air expelled from the syringe by pushing the plunger to its original po sition. The aspiration is repeated until the end point is reached and the volume of air recorded. Since the amount of con taminant required to react with the quan tity of absorbing solution is known by calculation, this amount is present in the volume of air scrubbed. Further calculation reveals it in terms of parts per million. The device has been successfully used for testing industrial atmospheres for am monia, sulfur dioxide, hydrogen sulfide, and hydrogen cyanide. It has also been used for collecting samples of other at mospheric constituents such as formalde hyde and alcohol for subsequent laboratory analysis. It has been especially useful for testing the "Airftuent" of vent stacks for ammonia, sulfur dioxide and hydrogen sul fide. In this case, stronger solutions must, of course, be employed. The successful use of the device is based on the utilization of very dilute standard solutions which therefore require small volumes of air to effect color changes. Test ing the device for efficiency is superfluous because the reagents selected for the gases described have been in common use for the same purpose for many years and warrant the use of almost any type of scrubbing device. The procedures described below are those which have been satisfactory for field use. Sulfur Dioxide Reagents: 1. .0001 N Iodine (1 ml = .0032 mg. Sul fur Dioxide). 2. Fresh starch solution. Procedure: Pipette exactly TO ml of the iodine into a side arm test tube, add a drop of starch and scrub the air containing sulfur di oxide through the solution until the blue color is discharged. Record the volume and calculate the concentration of sulfur dioxide present using the following formula: ________ 10 X .0032 X 24,450 Vol. of air in liters X Mol. Wt. of SO, = PPM Example: Assume 1500 cc of air required: Then: 10 X .10.0532XX6424,450 = 8 PPM H ydrogen Sulfide Reagents: 1. .0001 N Iodine (1 ml = .0017 mg. Hy drogen Sulfide). 2. Fresh starch solution. Procedure: Proceed in the same manner as for Sulfur Dioxide. Record the volume and calculate the concentration of sulfur dioxide pres ent using the following formula: ________ 10 X .0017 X 24,450 _________ Vol. of air in liters X Mol. Wt. of H.,S. = PPM A mmonia Reagents: 1 . .0001 N Sulfuric acid (1 ml. = .0017 mg. ammonia). 2, Methyl Purple Indicator. Procedure: Pipette exactly 10 ml. of the acid into a side arm test tube, add a drop of indi cator and scrub the air containing am monia through the solution until the pur ple color changes to green. Record the volume and calculate the concentration of ammonia present using the following formula: ________ 10 X .0017 x 24,450 ______ Vol. of air in liters X Mol. Wt. of NH, = PPM H ydrogen Cyanide The procedure used for hydrogen cyaniae is the one described by White.*12 In this case, we use the syringe assembly instead of the rubber bulb used by White because of increased accuracy in reading the volume of air required to match the colors. dust rial Hygiejie Quarterly 25 On occasions, where the end point is not arp because of low concentrations of gas ing present there is an accuracy comnsation which exists between volume of r required for a good end point and con- centration of reagent used. An example can be given in the case of the determina tion of sulfur-dioxide using dilute stand ard iodine. If the concentration of sulfur dioxidp in the atmosphere is 8 PPM then by calculation 1500 cc of air is required to decolorize 10 ml of 0001 X iodine. A devi ation of 100 cc more or less from 1500 cc gives answers of 7 6 and 8 7 PPM respectnely. This deviation is of no consequence when it is considered that the practical significance of air sampling is the. indica tion of a range of concentrations which might exist during a working period and to which employee exposure might occur. Fig. 2 shows how the device can be mounted in a small carrying case. Since distilled water is usually available .IN solutions can be carried in sealed ampoules for further dilutions, and indicators can be placed in screw capped vials. References 1. Pearce, S. J . and ScHr z n k , H . H . : T he D ete rm in a tion of S u lfu r Dioxide in A ir by Meaxis o f th e M idget InapinRer, U .S. Bureau of Mine*, R eport of Investiga tion 4282, M ay 1948. 2. W hite, N orma.v G,; H ydrogen C yanide m an In dustrial H azard Methods of Detection and C on tro l dew n * e.an In d u stria l H yo ic n s A ssociation Q uarterly. 9:81, 1948. W.C.L. Hemeon Honored /~\N J a n u a r y 22, 1953, the Junior Chamber of Commerce of Pittsburgh, Pennsylvania sponsored a dinner at which b e n j a m i n f . f a ir LESS was acclaimed Pittsburgh's man-of-the-year. At the same time, w. c. L. hemf.on. Engineering Director of the Industrial Hygiene Foundation was accorded recognition tor outstanding contributions in air pollution abatement, indus trial dust control and ventilation. The honor was the 1953 Science Award which is given annually for outstanding contributions in the science fieid.