Help - Question on Reg Testing

[ttekippe]

Hi folks!

I'm heading off on a trip to the Carribean next week and got some gear back from my brother that I let him borrow last summer. I have an older Scubapro Reg that I have used two or three times a year for the last six years. I bought it used from a dive shop on a trip to Florida, they said it was recently serviced, I have never had it inspected or serviced since, but have never had a bit of trouble with it either.

Before the upcoming trip, I thought I ought to have it at least inspected. I called two LDSs, and one guy told me that he will do a bench test while I wait, and if all looks okay, he'll charge me a nominal fee - like $10. If it needs to be fixed, he likely has the parts in-stock, or can get them within a day or two.

The second shop I called, I talked to a guy who told me that he has a sophisticated test apparatus that can measure the amount of air that is exhausted, and that there is a risk that if it is not exhausting properly, that I could be re-breathing air that I exhale, and this could cause build-up of carbon dioxide through the dive, and the risk is that I could get light-headed, pass out, die, etc. He said there is no way to know if it is working properly without hooking it up to this test.

This sounds fishy to me. I could be wrong, but looking at the reg, it seems to me that the only place that carbon dioxide could build up is in the second stage of the reg. (It certainly can't get into the MP hose!) The available volume within the second stage is fairly small, compared to the volume inside your lungs, so how could this rebreathing problem happen?

Has anyone ever heard of danger from re-breathing air held within a regulator?

Does it sound like this guy is trying to sell me something unneccesary? I'm leaning toward going to the first shop. Please let me know. Thanks!

 

[Hank49]

I"ve never heard of that problem. Like you said, how much air can fit inside the second stage. But if the reg is 6 years old and never been seviced (especially if you dive in sea water) I would have it serviced, put all new O rings and lube everything properly. Then have the guy put his "super machine" on it and test the intermediate pressure. Also do the second stage. The diaphram could be dry rotted as well as the o rings. Althoug you haven't done many dives with it, time does age o rings and rubber stuff.

 

[Damselfish]

The second guy sounds fishy to me too.

It's nice when people don't push unneccessary service, but did you tell the first guy it hadn't been serviced in 6 years (assuming the place you bought it told the truth)? 6 years is way too long and he probably _should_ be pushing you to service it.

 

[ttekippe]

No, I didn't tell him that. I'll take it there and see what he finds, then tell him. Thanks for the help.

 

[RiverRat]

The second guy sounds fishy to me too.

It's nice when people don't push unneccessary service, but did you tell the first guy it hadn't been serviced in 6 years (assuming the place you bought it told the truth)? 6 years is way too long and he probably _should_ be pushing you to service it.

Yeah sounds like BS. Get it serviced and tested. You may want to invest in an IP guage as well and learn how to use it. It's great for pre-dive testing. Gives you a good indicator of how your 1st stage is operating and can give you an indicator of a problem that could arise soon. Get with a good shop and tech and learn about your reg.

 

[DA Aquamaster]

The volume of air inside the second stage is fixed. There will always be some small amount of exhausted air that is rebreathed and will cause some small and insignificant amount of CO2 to be re-inspired. It's insignificnat because your throat and mouth are far larger dead air spaces that cause the same potential problem so the small extra volume of the second stage is not going to cause any noticeable difference. The dead air spaces in your lings/throat/mouth/reg are the reason that long slow deeper than normal breaths are important in diving to ensure more efficient ventilation.

If you are really concerned about the problem, a more effective solution would be to have your neck and throat shortened.

With regard to the second stage, the only potential problem that could be found or fixed would be a sticking exhaust valve. That would cause an increase in exhalation effort which in turn could result in you exhaling less than normal and cause CO2 buildup. But no special machine is required other than a magnahelic gauge that every LDS should have anyway. Even that is a bit of overkill as you can tell by exhaling into the reg if there is a problem with a stuck exhaust valve. In short the LDS with the special equipment the measures exhaust air volume is either a moron or a cheat.

Most SP second stages, with the possible exception of the D300,D350 or D400 will acquire a very significant seating groove in the second stage seat over the course of 6 years unless some sort of anti-set key or device were used while the reg was stored. The result will be that even if the second stage does not freeflow slightly, the inhalation effort will be higher than optimum. So it's very likely that the second stage, at a minimum, would benefit from an annual service.

$10.00 is a fair price for a flow test. The test will give an indication of the inhalation effort and whether it is still within acceptable limits. It will also provide some diagnostic indicators regarding the first stage intermediate pressue which is a good indicator of the condition of the high pressure seat and general condition of the o-rings. But if the second stage needs serviced, it makes sense to go ahead and do the first stage as well.

 

[darkstar]

... I bought it used from a dive shop on a trip to Florida, they said it was recently serviced, I have never had it inspected or serviced since, but have never had a bit of trouble with it either.

I would have the reg serviced by the first LDS. Six years is way too long even for a reg that rarely gets used.