Cracking a valve gives a trickle: to warm up a steam line, equalize pressure across a bigger valve, vent air, or check whether a line is live before opening fully. The same word gives cracking pressure, the point where a check or relief valve first begins to open. Operators crack a bypass first and listen before committing.
Crack the warmup bypass and let it sit for twenty minutes before you open the main steam stop.
Also heard as
- crack open
- cracked
Related terms
Cracking pressure
The pressure at which a check valve or relief valve first starts to open and pass a trickle of flow.
Bleeder
A small vent or drain valve used to release pressure or fluid, especially between two block valves.
Throttle
To hold a valve partly open on purpose to restrict and regulate flow or pressure.
Water hammer
A pressure surge, heard as a bang, when moving liquid is stopped or reversed suddenly.