Negative pressure test

[arj]

I've read that a negative pressure test on your reg should be part of all pre-dive checks. Can someone tell me how to do it and what it actaully checks for.

 

[redacted]

I've read that a negative pressure test on your reg should be part of all pre-dive checks. Can someone tell me how to do it and what it actaully checks for.

Attach regulator to tank & inflator hose to BC.

Place reg in your mouth and inhale.

If you get any air, something is wrong that may allow water to leak into where it should not be and/or air to leak out.

 

[Greg Barlow]

A normal inhalation is all it takes. If one were to inhale in a very forceful manner it is feasible that the exhaust valve could "flip" a section inward from the vacuum. Another similar test is to lower the unpressurized second stage into the water without letting water flow into the mouthpiece. Hold it for 30 seconds or so and then check to see if water runs out of the inverted mouthpiece. If more than a few drops exit, then a leak might be present. I carry out these tests about every 6-10 dives. I also routinely check the cracking effort and the intermediate pressure. These simple, quick tests can give you a very good indicator of your reg's proper functioning.

Greg