Gaseous fluid impact sensitivity (GFIS) test

Signs of ignition are visible through a small porthole during a gaseous fluid impact sensitivity or GFIS test of a non-metal PTFE sample.

Pneumatic impact testing is designed to assess the ignition sensitivity of nonmetals to compression heating that develops during an oxygen pressure surge (also known as pneumatic impact, gaseous fluid impact, and oxygen shock). This test simulates real-world conditions where nonmetals, including lubricants, may be rapidly pressurized with oxygen during system operation.

In the pneumatic impact (oxygen pressure surge) test, a sample of the nonmetal is placed in a sample cup positioned at the end of a surge tube. An upstream closed valve, holding high-pressure oxygen on its upstream side, is quickly opened to introduce oxygen to the surge tube, which causes pneumatic impact and compression heating at the sample, mimicking the transient pressurization that can occur in an operational setting depending on pressurization rates. Researchers observe how the nonmetal reacts to these conditions, looking for any signs of ignition or other undesirable outcomes.