March, 1928
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Testing Laboratory of the American Gas Association' Its Purposes and Accomplishments R. M. Conner and F. E. Vandaveer AYERIChN GAS ASSOCIATION, I N C, TESTINGLABORATORY, FOOT EAST62ND ST., CLEVELAND, O H I O
T
HE American Gas Association, through cooperOur national gas-appliance testing program will be made effective largely by securing cooperation beative efforts on the part of its gas company and manufacturer members, established a central tween the gas companies and appliance manufacturers. At the last American Gas Association convention, testing laboratory in Cleveland, Ohio, on June 1,1925. the gas company members pledged themselves to Gas companies contributed the funds necessary to ~ ~ ~ ~ and a l sell only A. G. A. approved ranges, finance its establishment, and the manufacturer mem- A ~ $ ! ~ ~ purchase space heaters, and tubing, since at that time other bers supplied a large share of its testing equipment. This laboratory was founded to insure the user appliances had not been tested. Many appliance manufacand the public in general safe gas appliances, assist the ap- turers have agreed to make only those which will receive pliance manufacturer in producing safe and efficient equip- A. G. A. approval. With such interest backing the movement, improve the art of appliance design, and eliminate for- ment and with cooperative advertising, the public will soon ever from the market a t the earliest possible moment ap- learn that an approved appliance is a quality product of proved pliances that do not meet proper concepts of substantiality, merit, and the only safe thing to buy. durability, and safety. Establishment of Approval Requirements Considering the number of people served and the millions of appliances now in use, the gas industry as a whole has All official tests are made to determine compliance with been remarkably free from accidents due to the operation of its appliances. However, since there has been a small approval requirements prepared by committee-meh reprepelcentage of accidents which might be attributed to imperfect senting gas companies and appliance mannfactureys as well appliance operation, the American Gas Association has as representatives from the Bureau of Standards, Bureau of decided to eliminate as nearly as possible the probability of Mines, U. S.Public Health Service, and the Master Plumbers Association. Such research work as is necessary in the such occurrences in the future. The manufacture and use of gas appliances for heating is preparation of the safety portion of these requirements is in many respects an old art. I n 1850 James Sharp delivered carried out by the Testing Laboratory of the American Gas a lecture on "Gastronomy" demonstrating gas cooking. In Association and the U. S. Bureau of Standards. The establishment of an official testing laboratory marks 1851 a Davis cooking stove was used in the United States. SOCIETY one of the most progressive steps ever taken by any industry In 1876, the same year the AMERICaN CHEMICAL in raising the standards of its was founded, the Royal Bakpublic &-vice. Contrary to ing Powder Company baked the procedure a d o p t e d b y cakes on gas stoves at the AMERICAN GAS ASSOCIATION, INC. most other approval laboraC e n t e n n i a l Exhibition in Testing Laboratory N~-.-tories and institutions, the Philadelphia. This a p p a r work of the American Gas ently simple historical event Association through its offimarks one of the important cial testing agency is based almilestones in the gas business. most entirely on public standHowever, it was not until ards or specifications, in the about 1895 that any great preparation of which impareffort mas made to popularize tial experts outside of the inthe use of gas for cooking and dustry cooperate actively and heating. Since that time cookthe results of which can be ing and heating with gas has verified a t any time by combecome an accepted practice. The fact that an appliance petent experts. The approval requirements has been manufactured for fifty pears does not necesas they are drawn up are sarily mean it is the best minimum requisites for satispossible product that can be factory performance, substanmade, There must always be tial and durable construction, progress and improvementand safe operation. In their new features added, new conpreparation sight was never veniences provided-and it is has k e n tested by the American Gas hisociatian, I n c , Testing Laboratory 2nd found to soinply lost of the necessity of providwith the approrai requirements of the American Gai Asmiation. in this field that a national This approrai shall be construed as applying only to the t)pe of a p p l i ~ ~ e . ing every o p p o r t u n i t y for dexice or appurtenance designated b y manufacturer's name, trademark, testing agency can be espenumber. conifructed eyacriy as ref forth above, and further identified by manufacturers to i m p r o v e the American C a s hirociarion'r Omciai Marking Seal. cially helpful. their appliances and to em1 Presented as a part of the body individuality in their Symposium on "Chemistry of Industrial Gas" before the Division of construction. It m i g h t be ALEXANDER FORWARD Gas and Fuel Chemistry at the 74th supposed that appliances conkU4WU*loMC" Meeting of the American Chemical structed in accordance with Society, Detroit, Mich , September certain requirements would Certificate of Approval I s s u e d t o Cover Approved A p p l i a n c e s 5 to 10,1917.
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IXDCS‘TEIAL A N D ENGINBERING CHBMISTRY
be the same, or essciitially the w i i c , regilrdlcss of the manufacture, the term “requirement” being easily capable of an interpretation conveying this thought. However, the requirements are so prepared that they are largely in the nature of laboratory performance requirements, with certain construetional restrictions that do not prevent the embodiment of ingenuity in design and improvement. Not being familiar with our approval standards, there is a. tendency on the part of some to misinterpret their meaning. As stated, they are minimum requirements and, what is more significant, they refer largely to the quality of performance, particularly its relationship to efficiency and safety, rather than to the manner in whicli an appliance shall be built. Our standa.rds do insure reasonably durable construction but they positively do not specify how many accessories shall be attached nor do they make any effortto classify approved
Gas Steam Boiler under Test
appliances in the order of their merit. To do so would react to the disadvantage of a large majority of the manufacturers co6perating in our testing plan and in the end result in endless controversies. Our present plan insures sa.fe arid efficient appliance operation. To attempt to influence the customer other than to recommend that he purchase one hearing the bloc star would be going much too far. Certainly we wish the customer to purchase the best appliance he can afford and, generally speaking, we believe with the facilities that we have provided that he will do so. Conditions of Routine Testing Before any rout.ine testing for approval of gas appliances could be done nationally, two major technical problems had to be solved: (1) What gases and what pressure variations should be used in making approval tests; and (2) what concentration of carbon monoxide should be established as the maximum allowable under any test condition.
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both variations in gas quality and the pressure a t which it is supplied. To determine what gases should be used during our approval tests, duplicates of the natural gases served in Ohio, Pennsylvania, West Virginia, and Southern California were used. Manufactured gases similar to those distribut,ed in Boston, New York, Philadelphia, Baltimore, Washington, Chicago, Denver, Tacoma, Portland (Ore.), San Francisco, and mixed gases similar to those distributed at that time in Los Angeles and Pittsburgh were duplicated. These gases are representative of those served in all our principal cities. Tests on them covered heating values from 400 to 1125 B. t. u. and specific gravity variations froin 0.37 to approximately 0.7. The air required for complete combustion also varied from 3.5 to 11.2 cubic feet per cubic foot of gas burned. At the present time the usual gases being delivered to the domestic customer vary in heating value froin 400 €3. t. u. to somewhat above 1200 B. t. u. per cubic foot and in specific gravity from 0.34 to 0.7. The pressure at which these gases are distributed when considered over the whole country may vary from 2 to 10 inches water pressure. These conditions naturally necessitate determining whether or not tests should be made on all or one kind of gas with the attendant variations in pressure. To prove conclusively how these conditions would have to be met, by attempting to anticipate every local condition, would have created such a complicated problem that it would have required yean of research work to solve it. On the other hand, to find out what might be termed the worst conditions ordinarily encountered in service and to anticipate their effect on the appliance subjected to them is more simple problem. The second procedure was sleeted and proved to be much easier and more satisfactory than expected. Therefore, as a result of these findings, tests are now made under the most severe conditions that appliances are ordinarily called on to meet with the knowledge that if they pass these testa they should prove even more satisfactory under average service condit.ions. A rather careful survey of gas-pressure conditions over the United States indicated that 3.5 inches of water column was about average for manufactured gas and 7 inches for natural gas. These figures were chosen, therefore, as the normal pressures for these respective gases. Permissible pressure variations usually equal about 50 per cent either way from these average figures. In a general way the approval tests prescribed were made to fit these conditions. Space heaters, water beaters, and central househeating appliances are required to meet a 50 per cent variation either way from the normal pressure on both manufactured and natural g a without compensating adjustments in the air or gas supply. This insures that approved appliances must possess, in addition to other qualities, a very high degree of flexibility. After considerable investigation it was found that the two gases representing the extremes in heating value and the gas having the lowest specific gravity were the most diBicult gases to burn by present-day appliances and that any appliance that would operate satisfactorily on them would perform even more satisfactorily on other gases with specific gravity and heating values ranging in between. Our research work indicated that most natural gases possess the following characteristics: (1) A high hydrocarbon content rcsiclting in slow buniing condition. (2) They require a l a r ~ evolume of air for coin~letecontbia-
Kind of Gas and Pressure
It is obvious that an appliance may work perfectly on one kind of gas with a certain pressure and yet not do so nuder other service conditions. For this reason it is necessary to insist on a rather high degree of flexibility with respect to
13) The specific gravity is not very much greater than some of the g a x s of lower heating value, particularly coal gas; therefore, its kinetic energy for air entminment is comparatively
low.
Xarch, 1928
INDVSTllldL A V D EXGINEEHNG CHEMISTRY
A manufactured water gas of low heating value with a 0.7 specific gravity usually possesses the following characteristics:
(‘1
High hydrogen and carbon monoxide content,
its being a rapid burning gas. (2) A small volume of air required far complete combustion, iieecssitating entraiiuneiit of only a sinal1 amount of primary air. A high percentage of inerts (carbon dioxide and nitrogen) (:i) oyer. iliiici~ flood the burner with inert and h crowd the average gas range, water heater, or space heater burner, which is usually built for a higher 8 . t. u. gas. iii
Coke-oven gas of about 500 B. t. u. and 0.37 specific gravity generauy has the following combustion characteristics: (1) High hydro~encoiitent, creating a comparatively fast burning long flame condition. (2), Low specific gravity which does not give sumeient kinettc eqerpy to the gas stream to inject large quantities of ,,nmary a r . AIAXIMUM CARBON MONOXIDE CO~CENTRATION-Parallel aith this invesiigation research on the establishment of a safety standard for completeness of combustion was conducted. This work was done jointly by the U. S. Bureau of Standards and our establishment. Logically the first consideration in establishing a requirement for carbon monoxide is the maximum concentration human heings can breathe over a given length of time and feel no ill effects, and wit,h this information in mind provide a factor of safety sufficiently large to insure safe operation nuder any reasonable service condition. According to such eminent authorities as Dr. Yandell Henderson2 and Sayers, Meriwether, and Y ~ i n t there ,~ are no deleterious effects on the human system when exercising or a t rest when breathing an atmosphere of 0.03 of one per cent carbon monoxide for one hour. Accordingly a good gas appliance should produce no carbon monoxide, or a t least such small quantities that it would have no effect on the human system. Consequently the limit permitted by the approval requirements of the A. G . A. for gas ranges under the most severe test conditions is one-third of the fignre given hy Henderson and Sayers, or 0.01 of one per cent concentration in a 1000-cubic foot room having four air changes per hour. For space heaters there are two requirements-one when the heater is burning in a normal oxygen supply, and the other when the appliance is burning in a room with a decreasing oxygen content. The second test is supplied in order that the customers may be safeguarded in cases where the heater is operated in a aniall and poorly ventilated room. Under the first condition the maximum alloaahle concentration is 0.02 of one per cent in the air-free products of combustion (0.002 to 0.005 per cent in the sample); under the second condition of a reduced oxygen supply, 0.05 of one per cent. These conditions figure out abont one-tentii of the concentration required to produce any harmful effects. For water heaters, boilers, and furnaces, as such applincw are usually vented, the requirement is 0.04 of one per cent in the air-free products OF combustion, giving a saiety factor of about 5, under any usual service condition. These concentrations are probably lower than would he encountered where several men are smoliing in a room, and certainly less than results from automobde exhaust on one of our busy streets.
Apparatus Used in Tests In conducting its research and routine testing work, the American Gas Association’s Testing Laboratory uses three types of apparatus for accurate determination of the comJ . I n d . fly#., 8 . 79, 137 (1921). U. S . Pub. HeoUii Scrvirc, Pub. Health RcpU. 87, 1127 (1922). re. print NO. 748. 1 8
309
pleteness of combustion. Equipment ordinarily used for gas analysis--such as the Burrell, modified Orsat, Orsat, Hddane, pyrotannic acid, and canaries-& not sufficiently accurate for determination in the thousandths of one per cent. Three types of apparatus-the iodine pentoxide apparatus, the thermal and the recording carbon mono& apparatus-have been iound very sntisfa&y. Successful development of the first two machines was accom~lishedby the U. S. Bureau of Standards; the third was perfected by the U. S. Bureau of Mines and the Mines Safety. Appliance .. Company’ Determination Of carbon monoxide iodine pentoxide is based upon the reaction of carbon monoxide and iodine pentoxide, forming carbon dioxide and iodine. The iodine liberated is sublimed, collected in potassium iodide, and titrated with 0.001 N sodium thiosulfate. From the amount of thiosulfate used the uercentaee of carbon monoxide in the sample can he calculate& In the thermal-conductivity apparatus the analysis of the gas is determined by the rate a t which heat is carried by the gas under standard conditions. The recording carbon monoxide apparatus passes a measured amount of gas through a catalyst called Hopcalite (an intimate mixture of copper oxide and manganese dioxide) maintained a t 100’ C. by a steam bath, the carbon monoxide being selectively oxidized by the IXopcalite. The reaction liberates heat, which is transmitted to a thermopile imbedded in the Hopcslite. Tile electromotive force generated is recorded by a recording potentiom~
Sampling Product8 of Combusdon from Space Heater
eter which is calibrated in per cent carbon monoxide. AI1 these apparatus are capable of an accuracy of 0.002 of one per cent. The laboratory m&es between forty and sixty determinations per day to this degree of accuracy. Certificate of Approval and Inspection System When appliances pass the laboratory test the manufacturer is given a certificate of approval and permitted to display the laboratory approval seal, which is a blue star surrounded by two concentric circles containing the words “Testing Laboratory Approved.” Where changes are made in the essential features of construction on any appimnce during each year, the manufacturer must notify the laboratory of this change and, if it is one that affects combustion, resubmit this appliance to the laboratory for test. An inspection system is also maintained to see that appli-
INDUSTRIAL A N D ENGINEERING CHEMISTRY
310
ances bearing the laboratory seal of approval are being sold as approved. These inspections will be made at least once a year and more often if necessary. Where proper standards are being maintained, approval certificates will be issued covering each succeeding year, and once secured, are good indefinitely unless some changes are made that require additional tests. Accomplishments to Date During the past two years the laboratory has conducted research in the preparation of safety requirements for gas ranges, space heaters, water heaters, and central househeating appliances, and also approved from test or inspection approximately 6000 gas ranges, 300 space heaters, 50 water heaters, 15 types of flexible gas tubing, and a number of central house-heating appliances. Considering that there are about 175 tests made on a gas range, 250 tests on a space heater, 200 tests on a water heater, and 150 tests on a central house-heating appliance, this demonstrates that an enormous amount of work has already been done. Research on Mixing Gases While the work of the testing laboratory is largely confined to routine testing, considerable research work has recently been done on mixing gases. This subject has become very important to every one in the gas industry. In some localities the natural gas supply is rapidly decreasing, necessitating mixing with the natural a manufactured gas of different heating value and different specific gravity. In other localities a large quantity of by-product coke-oven gas of low specific gravity is available, but there is not a sufficient quantity to supply the entire demand. Therefore, it is mixed with another gas, usually carbureted water gas of about the same heating value but much higher in specific gravity. The supply of oil, being somewhat doubtful, may necessitate mixing oil gas with coal or some other kind of gas as the price of oil increases. The gas industry as a whole is interested in the question of how far jt can go in varying specific gravities, or heating values, or both, and still maintain satisfactory appliance operation. It is an easy matter t o manufacture and mix
Vol. 20, No. 3
gases of different heating value and specific gravity, but the question arises as to how closely the mixing must be regulated without affecting the operation of gas appliances already in service. The laboratory is obtaining fundamental data on this subject. Although the whole investigation may not be finished for three or four years, the first phase of the work-that of finding out the effect of varying the specific gravity, the heating value remaining constant-will soon be completed. Investment At the present time the testing laboratory represents an investment of about $500,000 on the part of the gas industry, $125,000 of which was contributed by gas-company members; the remainder represents test fees that have been used partially to retire operating expenses and investments necessary on the part of appliance manufacturers to bring their equipment up to present standards. Importance of Undertaking With the hearty cooperation of every one concerned in this undertaking the testing laboratory is sure to succeed. It is founded by a great industry in the interest of better public service. It is raising the standards of construction and performance of gas-burning equipment and developing the art of appliance design. Already there are many signs of new developments, and a marked improvement can be seen in the approved ranges and space heaters being sold a t the present time. The same can be said of water heaters and central house-heating appliances, when they are added to the approved list. This will also be true of other types of appliances submitted later for tests. The gas industry appreciates the value of science in business. It realizes that it cannot with justice to the future of its business afford to shape its appliance policies after the customs and traditions of the past. The establishment of the Testing Laboratory was an epoch-making advance in the gas business and public evidence of the industry's consciousness of its moral responsibility to safeguard to the best of its ability the millions of people who are daily dependent on gas as one of the essential services of life.
Properties and Uses of an Edible Rice Cellulose' E. R. Harding MELLON INSTITUTE
A
OF IXDWSTRIAL REsCARCH, UNIVERSITY O F PITTSBURGH, PITTSBURGH,
RECENT advance in food technolow -" is the develoDment of a process of recovery of an edible celluloie from the hulls of rice and other cereals. Cellulose is a natural constituent of practically all vegetable foods and is really an essential dietary constituent. By adding bulk and roughage to the intestinal contents normal elimination is promoted and constipation largely prevented. In the development of a new ready-to-serve breakfast food milled rice was found to be the most desirable cereal base. Because of the low cellulose content of milled rice it was decided to reenforce the roughage content of the finished cereal by additions of a pure cellulose of suitable physical form. It was found that a satisfactory pure edible cellulose could be prepared from the hull of the rice, thus making the breakfast food an all-rice product. The cellulose of the hull is first isolated in a semifibrous form by a strong soda cook. A hydration treatment then reduces it to the proper physical form for use as an edible material. 1
~~~
Received December 24, 1927.
PA.
A large plant for the production of this new form of pure cellulose has been in operation for some time. It is located at Lake Charles, Louisiana, adjacent to the largest rice mill in the world. Rice cellulose as prepared for food roughage is a light, somewhat fluffy, fine, mealy material. It has a light cream color, but is easily bleached white if desired. It is odorless and tasteless. It has a mealy feel in the mouth, and although not intended to be eaten straight, when well moistened with saliva, can be swallowed without difficulty or irritation. Its ash content has been reduced to 1.0 per cent or less, although the original raw material contains about 18 per cent of ash that is largely insoluble silica. The washed product from the alkaline digestion may run as high as 99 per cent alpha-cellulose. In the finished product a part of the original compound or normal celluloses has been converted to simpler hydrated celluloses; but the freedom from impurities of noncellulosic character entitles it to be called a practically pure cellulose.
