[PSUBS-MAILIST] Acceptable cabin pressure swing

[Jon Wallace via Personal_Submersibles]

I think this is somewhat subjective but what is general consensus on 
maximum cabin pressure swing (higher/lower) relative to hatch closing at 
the start of a dive before setting off alarms?  My thought is that an 
alarm should sound well before any point of emergency.  I'm considering 
sounding a warning at 2psi +/- and an alarm at 4psi +/-  but I'm not 
sure if this is too strict.

Jon