Removing and refitting a 1st stage underwater

[NotDeadYet]

If you've got a gauge on it then you'll wreck the gauge as water will get blown up the bourdon tube (sounds like it may be related to Berko's 1st stage up the arse story but isn't).

Other than that you won't stop the reg from working. If you let the water remain in the 1st stage then it may corrode some parts depending on what they are made from and salt crystals may wreck rubber seals. If you dismantle the reg fairly soon after, clean everything, dry and relube it before re-assembling then it will be fine. In the short term, removing a LP & HP plug and cracking open a bottle "should" remove most moisture. But then condensation in the bottle your draining might be your next worry

Originally Posted by A.Berk

I've often thought how much that would sting if it occured behind one's head!

Quite a lot. I had a Swagelok metering valve decide to release itself from a hose on an O2 bottle I was carrying over my shoulder and luckily my head stopped it hitting anything vital. 250g of brass can make you say rude things out loud.

We would often stow a spare twinset in our dive basket to keep us going at shallow depths. Changing regs over to a fresh set was the norm

I knew some Russian research divers who used to dump all their reg sets into a bath of salt water every night to stop them freezing. They never dried out so never had problems with salt crystals or corroding. So they said...