edward t:

Changing removable lpg tanks should propose little fire risk provided there is no defective equipment involved and one of the OSHA required methods is used. I perceive the greater fire risk to be during the cylinder recharge operation. I think most of the bulk tank portable cylinder filling devices are equipped with manual controls. Inattention, poor reflexes, or defective equipment could spell disaster. Liquid propane has an expansion ratio of 270 volumes of gas for 1 volume of liquid exposed to air.

"OSHA 1910.110, Storage and Handling of Liquefied Petroleum Gases

OSHA, 1910.110(e)(5)(iv)(e)

When removable fuel containers are used, means shall be provided in the fuel system to minimize the escape of fuel when the containers are exchanged. This may be accomplished by either of the following methods:

OSHA, 1910.110(e)(5)(iv)(e)(1)

Using an approved automatic quick-closing coupling (a type closing in both directions when uncoupled) in the fuel line, or

OSHA, 1910.110(e)(5)(iv)(e)(2)

Closing the valve at the fuel container and allowing the engine to run until the fuel in the line is consumed."