Refrigerants Tested for Toxicity AT THE Atlanta, meeting of the AMERICAN CHEMICAL SOCIETY
the first report was made concerning dichlorodifluoromethane, which was described a s a non-toxic refrigerant. Subsequently, certain characteristics o f this material, which has become known to the trade a s Kinetic No. 12, or as F 12, have been determined and t h e results given considerable publicity. There has been no similar information available with reference to commonly used refrigerants, s o that no proper comparison has been possible. Kinetic Chemicals, Inc., therefore arranged for the Jackson Laboratory of E. I. du Pont de Nemours & Co., Inc., i n conjunction wih Robert A . Kehoe, of the Kettering Laboratory of Applied Physiology, University of Cincinnati, Cincinnati, Ohio, t o conduct a series of thorough-going tests. These were carried out at Deep water Point, N. J., October 28 and 29, 1931, and the results nave now appeared in very complete form. For the purpose of making the tests, a building 10 X 10 X 10 feet was constructed o f wood, with the floor, ceiling, and two adjacent sides lined with galvanized sheet iron, with seams sealed with Pecora cement. Each of the other two walls was composed of three wooden frames covered with moisture-proof Cellophane. A s e t of newly covered frames was used for each test and permitted all present to observe what was going on in the room. This building was equipped with a two-burner gas stove located in one corner, a fan to insure thorough mixing of the refrigerant with t h e atmosphere, means of introducing the refrigerants, of withdrawing samples of decomposition products for testing, and such other equipment as might be needed t o make all determinations of any interest or significance. All the control apparatus was located outside the building. There were meters for measuring t h e butane gas burned in the stove, scales for weighing t h e refrigerants admitted to the building, apparatus for absorbing the acid vapors and measuring the volume of t h e gas samples withdrawn. The gas could be ignited b y means o f two spark plugs. When used, guinea pigs were confined in cages—one on t h e floor and the other suspended in the room at an elevation of 5 feet. The conditions of t h e test were purposely made extreme and severe. The rooru was sealed and had no outside ventilation whatsoever. The atmosphere was circulated at high velocity t o bring the vapors of the refrigerant into contact with t n e open gas flames, and in every case the refrigerant was eitbier discharged immediately into t h e test building or allowed to escape a t a far more rapid rate than\ could be the case from the average leak. The results of some of t n e tests were easily predictable b y anyone familiar with t h e characteristics of the refrigerants, but nevertheless the "whole series was run through as planned in order that nothing might b e left to conjecture. The following
REFEJGBRAJNT
Sulfur dioxide Dichlorodifluoxometh&ne (Kinetic 12) Methylene chloride Methyl chloride Carbon tetrachloride Carbon dioxide Ammonia P r o p a n e (A) P r o p a n e (B) Isobutane
table is a summary of physical and chemical data on the refrigerants tested:
REBVRIQERANT
CHEMICAL FOBMULA
BOILING PT.
LIQTJID DENSITY SP. AT FL/,MV O L . B . P . UABLE Cu.
Sulfur dioxide SOs Dichlorodifluoromethane (Kinetic CCliFj 12) Methylene chloride CHiCU CHaCl Methyl chloride Carbon tetrachloride ecu Carbon dioxide Ammonia CO* Propane NHi Isobutane CsHs CUHJO
EXPLOSIVE LIMITS
ft./
» F.
lb.
14
6.7
— 21.6 3.3 104.2 — 11.4 7.5 170.2 — 109.3 9 i 9 — 28 25.4 — 48.1 9.7 8.1 7.3
1.46
No
Vol. % Not explosive
1.48 1.34 0.998 1.59
No No Yes No No Yes Yes Yes
Not explosive Not explosive 8.1—17.2 Not explosive Not explosive 16.0—25.5 2.4— 8 . 4 1.8— 8 . 4 5
o!éà 0.585
The tests were arranged in four series to show the toxic, irritant, and flammable characteristics of the refrigerants. In the first series each, test consisted of two parts: First, 10 pounds of the refrigerant were admitted into the test building during a short period of time and the behavior of the animals was carefullyobserved for 15 minutes; second, the two gas burners were lighted and allowed to burn for 30 minutes, or until definite conclusions had been reached. The conditions, as previouslypointed out, were severe and the probability of similar ones ever arising in actual use is exceedingly remote." In a second series 3.5 pounds of refrigerant were used and the gas was lighted immediately after the discharge of the material into the building. The third series consisted of exposing animals in small enclosures to an atmosphere containing various concentrations of the refrigerant in the absence of a gas flame, in order that the effect of the refrigerants themselves might be noted. Because of the time factors, these tests could not be run in the test building. The fourth series consisted of such tests as a representative committee selected on the spot might suggest for the completion of the data. Limited space prevents a more detailed account here, nor can we repeat all the data obtained, including observations on the guinea pigs used in the tests and autopsied. The tables given below summarize the more significant results of the series of tests. The report from which this information is taken points out in the introduction that "when judging the possible hazard to life and property which may be introduced by the escape of a refrigerant, the following factors must be considered : First, what effect will the refrigerant itself have on human life? Is it toxic? SUMMARY OF SERIES I TESTS I s it irritating? If toxic, is its action immediate or delayed? If toxic, does it give -ANALYBESsufficient warning of its presence? Second, 30 Mint, after iLigh Lighting G a s 15 Mint, after Lighting Gas CO will the refrigerant or its vapor introduce Total Halogen Aoids CO* Total Haloger* Acids - CO; — locit fire or explosion hazards? Third, will its % % % % % physical properties, such as vanor density, Present H P -H HCI, O.07 0 . 1 8 H F -h HCI, 0 . 1 8 0.3 rate of evaporation or diffusion, increase the (qual.) hazard?" Finally, it should be determined HCI, O.ll 0 . 0 7 HCI, © . 3 0 O.09 Present (qual.) whether circumstances surrounding the ordiHCI, 0 . 6 9 HCI, O . l l 1.16 Absent O.O nary use of refrigerants may increase exist(qual.) ing hazards or even introduce new ones. An Present HCI, O.06 0 . 2 0 HCI, O.ll 0. (qual.) example would be the possible formation of products of combustion or gases of decomposition when the refrigerant is brought into
O.02 O.06 O.09 O.05 O.02
-EXPOSURE AND ΕΆΤΕ OF ANIMALS -
Sulfur dioxide Dichlorodifluoroxnethante (Kirretio 1 2 } Methylene chloride
S 17
After Lighting Cas Before l i g h t i n g Gas Lower Upper Lower Min, Min. Min. Died β Died 27 Died N o t affected 17 Not affected 24= Died
20
Unconscious
20
Methyl ctiloride
17
17
Carbon tetrachloride
19
Carbon dioxide
2S
Intoxicated; helçle ^ Intoxicated; helpless N o t affected
Intoxicated; helpless 19 Iotoxicatecl; helpless 28 Not affected
Ammonia Propane
