Unbalanced 1st Stage with Air Source

[Johnny Kain]

I have a Apeks ATX50 reg which has an unbalanced 1st stage. I am currently using an Air Source integrated inflator and secondary reg. I had an issue with it leaking a small amount of air on a dive last year. A DM was there and said that the issue was that I shouldn't have an unbalanced 1st with an Air source secondary reg.

After making an adjustment to the airsource it has not been a problem since but it is still bugging me a bit. Is the unbalanced 1st with the air source a bad combo?

 

[halocline]

I would assume that your 1st stage is an unbalanced piston like the SP MK2, correct? The IP probably drops about 10-15 PSI over the supply range. But there's no reason why that should be a problem with the octo/inflator, any more than it would be a problem with any downstream unbalanced 2nd stage. You just set the IP fairly high, so it drops through the recommended range, and not below it, during the dive, and you tune the 2nd with a full tank. The slight freeflow has nothing to do with the balanced/unbalanced issue.

It is true that balanced 2nds will tolerate a wider range of IP variance than unbalanced, but since most unbalanced 1sts are sold with unbalanced 2nds, it's something you just deal with by setting the 2nd stage cracking pressure correctly, I.E. with a full tank so it matches with maximum IP.

 

[Johnny Kain]

Thanks. It is actually a diaphragm 1st stage but I assume that won't make a difference.

 

[halocline]

Actually, it does. Diaphragm 1st stages have an upstream valve and if not balanced, will experience an increase in IP throughout the supply range. Personally I don't know of any unbalanced diaphragm regs, what is yours?

Anyhow, you'd want to tune the 2nd stage with a low tank pressure when the IP is the highest. If you're curious about this, try borrowing or buying an IP gauge and measure your first stage with both a full tank and at 500PSI, then compare the two.

 

[DA Aquamaster]

I am also unaware of any unbalanced first stages that have been made in the last 30 years.

If it is a balanced piston first stage, you want to tune the Air Source with the reg attached to a full tank (3000 or 3500 psi depending on the tanks you use.)

 

[beanojones]

(You have an ATX50 with an unbalanced first stage?)

I think the moral of the story is that what most divemasters say about gear should be taken with a grain of salt.

It seems like if downstream 2nd stages (aka unbalanced 2nd stages) were a problem, most people's octopus's would leak, since most octopus of any kind are unbalanced. And just about all rental gear would leak.

The problem with most alternate inflator regs is that most owners flood the second stage with water every time they wash their gear.

 

[widget]

The fact that AFTER the adjustment it was fine, means the Airsource was probably set a bit fine for your 1st stage initially.

Balanced or unbalanced 1st stage is immaterial, its the fine tuning that is critical. If its fine now, I would just leave it.

 

[redacted]

The problem with most alternate inflator regs is that most owners flood the second stage with water every time they wash their gear.

Would you care to explain how flooding a second stage with clean fresh water would have any effect as long as it can't get back to the 1st stage?

Where do you get this nonsense?

 

[ZzzKing]

I think the moral of the story is that what most divemasters say about gear should be taken with a grain of salt.

I wholeheartedly agree.

The problem with most alternate inflator regs is that most owners flood the second stage with water every time they wash their gear.

I wholeheartedly disagree. I used an Atomic SS1 for over a year and took the thing off after every dive day and ran the garden hose through it for several minutes. It was the easiest to clean second stage that I have ever seen. I don't see that as being a problem.

 

[beanojones]

Would you care to explain how flooding a second stage with clean fresh water would have any effect as long as it can't get back to the 1st stage?

Where do you get this nonsense?

Would you care to explain how flooding a first stage with fresh clean water would have any effect?

Where did you get your manners?