Poppet valve 1 is inserted into standard sleeve 2, which is mounted in the body of the instrument. The valve face is pressed into the conical seat by lever 3, which turns about fixed axis A and contacts the valve through cover 4 and thrust member 5. Member 5 is loaded by spring 6. Compressed air is delivered from the pneumatic measuring device to chamber a of cover 4. If the face of the valve is concentric to its stem, no air passes through the joint between the valve face and seat in the sleeve. This raises the pressure in chamber a, as indicated by the pressure gauge of the instrument. In case of runout of the valve face with respect to its stem, air leaks out between the face and seat joint and escapes to the atmosphere through hole d. At this, the pressure drops in chamber a. When knob 7 is depressed, lever 8, turning about fixed axis B, lifts out the tested valve.
$3931$LHP,M$