Checking out a second stage

[Aigtbootbp]

Would it be possible to check a second stage for operation by simply swapping it out with an octopus (or alternatively simply using one of the extra low pressure ports if available)? It came up in a discussion as a hypothetical. Of course once hooked up it would be used in a dive with the known good secondary taking the place of the octo just in case something was wrong.
This is just a question, not a cheap way out to avoid an inspection/service.

 

[LeadTurn_SD]

Hi Aigbootbp,

You can test a great deal of a 2nd stage's function without getting it "wet"; and in fact it would be very wise to do as much "checking & testing" as possible prior to diving with the 2nd stage.

Take a look at this thread:

http://www.scubaboard.com/forums/regulators/260452-regulator-checklist-inspection.html

After I rebuild a regulator, and completing all dry land testing, I'll typically stick it on a AL30 pony bottle for the 1st couple times I dive with it, and test it at various depths before deeming it "good to go".

If I just needed to just test out a 2nd stage I'd rebuilt I'd be "ok" using the method you mention (attaching it to a known "good" 1st stage with a known "good" 2nd stage). If any problems were found with the "test" 2nd I'd go back to the "good" 2nd and abort the dive.

None of this advice substitutes for having someone knowlegable inspect and possibly service the 2nd stage if you have any doubts about it's history.

Best Wishes.

 

[fppf]

I would not suggest doing that.
If the regulator in question starts to free flow it will deplete your only air supply.

 

[halocline]

Can you clarify your question please?

Attaching a 2nd stage to a different LP port tells you nothing, all the LP ports just go to the same chamber. What am I missing?

 

[Aigtbootbp]

We were talking about checking a second stage for operation by removing an octo and replacing it with the second stage in question. This would allow someone to dive using the regulator to check it out for proper operation. It it failed one could immediately switch back to the known good (second stage) regulator and abort the dive.
this hypothetical made us think if a first stage regulator has more available LP ports then why not attach as many as you would like (or could) and check a few of them at once.
Just dive in using first suspect regulator and after a few minutes check out the second suspect regulator. If at any time something bad happens immediately go back to the known good regulator and surface.
Of course all of these would be on the same first stage.
Think of it as a christmas tree of second stage regs all hanging off one first stage.
Oh, this would be simply a dive to check out the equipment, nothing fancy or dangerous. Just a way to check these regs for operation.

 

[BabyDuck]

it would work, but i can't think why you'd need to do that. wouldn't bending over in waist-deep water with your gear on give you the same thing? you breathe from both before you go under anyway, right?

 

[halocline]

Okay, I see. It's true that by far the most common 2nd stage failure is freeflow, so your test dive would have to be shallow enough so you could quickly surface if the stage in question started flowing. You would definitely want to do this in warm water as well. Maybe a nice big bathtub would be the best.

Then there's the issue of tuning a 2nd stage to a specific 1st stage. This is especially important with unbalanced 2nd stages. You could try it out on one 1st stage, it could work perfectly, then put it back on the original 1st stage and it could flow.

I really don't see the advantage here. It's extremely easy to test 2nd stages on land and with a sink or bucket.

As far as using one 1st stage to check out several 2nds on one dive, if they all started flowing you'd have one monstro drain on the tank. Granted that's a slim possibility, but if it happened it would be entertaining to watch.