Safety in Transferring Dangerous Acids A new pneumatic acid syphon has just been placed on the market. It is used in transferring acid from the carboy to fire extinguishers. An air pump is used—similar to an automobile tire pump—and the air pressure causes the acid to flow out through a tube. There is an automatic valve in the head of the syphon which acts as a safety. This valve can also be operated manually when the operator desires to stop the flow of acid.