Can thermal mass flow meters be used with combustible gases?

Thermal dispersion flow meters can be used in combustible gases. Typically very little heat is added to the system (how much heat depends on the manufacturer). Sometimes customers ask us this question, as they are worried about exceeding the auto-ignition temperature of the particular gas. The maximum temperature rise of our sensor recorded by FM during the approvals process was 4K above ambient. Therefore, this little temperature added to the process temperature does not cause ignition, but it should be evaluated as needed on an application basis with the proper manufacturer.