On August 25, 1919, James S. Cunningham, foreman miner of Bureau of Mines rescue car No. 2, died while wearing a Salvus ½-hour apparatus in a gasoline storage tank of the Sinclair Oil & Refining Company, Trinidad, Colorado.
The gasoline tank had a capacity of 12,000 gallons and was about 18 feet high. There was a manhole at the top and a steel ladder on the inside leading from the manhole to the bottom of the tank. The gasoline in the tank at the time of the accident was about 7 inches deep.
Cunningham tested and checked the apparatus carefully on the rescue car and proceeded directly to the place where he had volunteered to enter the gasoline tank to make a pipe connection. He entered the tank through the manhole, went down the ladder to the bottom, and then returned to the top to make sure his apparatus was functioning properly.
Two employees of the oil company stayed at the manhole at the top of the tank. It was reported that a suggestion was made that a lifeline be used, but since it was not immediately available, Cunningham decided to enter the tank without it.
After determining that his apparatus was functioning properly, he went down the ladder the second time and found the place where the connection was to be made. Immediately thereafter, and before starting to work, he exhibited signs of confusion or distress, then fell over into the gasoline, lying with his head submerged in the gasoline. His body was later recovered with a grappling hook.
The apparatus was sent to the Pittsburgh Experimental station of the Bureau of Mines for inspection and testing; it was found that the rubber lining of the breathing bag had deteriorated, with the sides adhering together. The inside rubber was found to be gummy, and the rubber lining on the outside of the fabric had been almost completely dissolved.
Tests were also conducted on a similar apparatus, a duplicate in every way to the one Cunningham used, by subjecting it to gasoline in both vapor and liquid forms. The conclusion from the tests was as follows: "The experiments show that gasoline and also gasoline vapor in higher concentrations can penetrate the thin rubberized bags such as have been used on the ½-hour oxygen breathing apparatus …"
This accident led to development of heavy rubberized breathing bags for oxygen apparatus that are now used on some of the modern mine rescue equipment.
Subsequent tests on heavy bags revealed that high concentrations of gasoline vapors will, in time, penetrate even them. The Bureau therefore, recommended that the heaviest-type breathing bags should not be used in gasoline vapors longer than 2 hours in all, after which the bag should be discarded or thoroughly soaked and washed with water and aired out before reuse.
It is also recommended, when it is necessary to enter a place containing gasoline vapors while wearing an oxygen breathing apparatus, that a rope or safety belt is employed, and that the apparatus man or men are watched closely so that they can be withdrawn immediately in case of distress.