Flowgrid Slam Shut | 19
Troubleshooting
Problem
Likely Cause
Fails Internal Leakage Test
Flapper Seal is damaged,
Flapper sealing surface is damaged.
The external equalization valve is open or leaking.
The inlet supply to the pilot is not connected to the center port on the SSV.
Fails External Leakage Test
Damaged o-ring or seal
Damaged seal groove
Pawl lever stays in the unlatched position when
valve inlet is pressurized
The over pressure or under pressure set points have not been adjusted correctly.
-over pressure set point too low
-under pressure set point too high
-under pressure set point higher than the over pressure set point
-under pressure set point is set too close to the over pressure set point
The downstream (sense) pressure is not between the over and under pressure set points.
Over or under pressure valve dirty or damaged
Over or under pressure valve o-ring damaged
Vent valve plugged
Pawl lever does not unlatch the flapper
The over pressure or under pressure set points have not been adjusted correctly.
-over pressure set point too high
-under pressure set point too low
The convex side of the convolution on the actuator diaphragm is installed in the
wrong direction
Slam Shut closes during start up
The downstream pressure momentarily spiked over or under the slam shut set points.
