The use of multiway test gas cocks in a gas sample conditioning system is intended to switch between the gas samples entrance or the gas calibration entrance to the gas analyzer.

The multiway test gas cocks can be manual or solenoid, if integrated in an automatic switching system.

According to the characteristics of the sample the test gas cocks can be in PVDF, PTFE or nickel-plated brass, or in more specific applications particularly when interacting with pure oxygen, in stainless steel.

The manual gas cocks can vary up to five parts. The most common solenoid test gas cocks in an automatic switching system are of the 3/2 and 2/2 type (usually closed – NC)..