When a pump trips, flow decelerates and reverses; a heavy swing check that closes late gets driven onto its seat by the reverse flow and stops that flow instantly. The bang and pressure spike can break supports, valves and instruments. Fast-closing spring-assisted, nozzle or dual-plate checks reduce slam by shutting before the reverse flow builds.
Check valve slam on pump trip is shaking the whole rack, swap it for a nozzle check and see if it settles down.
Also heard as
- check valve slam
- slamming
Related terms
Check valve
A self-acting valve that lets fluid pass in one direction and closes on its own when flow tries to reverse.
Water hammer
A pressure surge, heard as a bang, when moving liquid is stopped or reversed suddenly.
Chatter
Rapid, violent opening and closing of a relief or check valve that hammers the disc against the seat.