Balanced vs Unbalanced: First and Second Stage Options

[scubamax]

Thumbing through the Rodales regulator reviews I noticed that a lot of the lower to mid priced regulators have a first stage which is balanced, and second stage which is not, and vice-versa.

I am aware of the benefits of having a balanced reg, but now am confused as to the benefits or drawbacks (if any) of having one stage balanced and the other not. Is there a clear advantage (apart from a fully balanced setup which would be the clear winner if one is looking for this type of system)?

I have searched for threads on this topic but have not found anything that gives me any clear discussion on this topic. If there is one out there point me to it and I will dive into it.

Thanks for your help.

scubamax

 

[reefrat]

Balanced First Stage

A balanced first stage is fairly essential in order to maintain a constant intermediate pressure (IP) to the second stage when the pressure in the tank gets low ( toward the end of the dive).
If the first stage is not balanced then the IP will drop slightly and the reg will be a little harder to breathe from.

Alternatively if the IP rises fro any reason (first stage out of adjustment or high pressure seat worn) then the reg second stage will freeflow.

Second Stage

A balanced second stage is not essential as long as the first stage keeps the IP constant.
However, if the second stage is balanced then a lighter spring pressure is required on the downstream valve to counteract the IP.
This can lead to an easier breathing (higher performance) regulator.

There are some perfectly good/ high performance regs without balanced second stages (eg Mares Abyss) but probably most top shelf regs these days have balanced first and second stages.

Hope this hasn't confused things!!?!

 

[scubamax]

reefrat once bubbled...


Hope this hasn't confused things!!?! [/B]

Reefrat,

The silt has settled a bit.

Thanks that does help clear things up. Not sure why one of the regs in the review has balanced second stage and unbalanced first, but then again this could be a typo. I agree both stages as balanced the way to go.



scubamax

 

[jeffsterinsf]

I'm not sure I agree with all the conclusions about balanced vs. unbalanced, especially at recreational depths (less than 3-4 ATA of overpressure compared to a typical IP of about 10 ATA). I would think that the intermediate pressure would have to rise quite a bit to blow the valve open in a 1st stage. If the IP "suddenly" rose abroptly, I would think this to be the last thing you'd be worrying about in that case!

Be that as it may, there have been arguments in the DIR community that your secondary air source should be a lower-performing reg, apparently to help prevent it from free flowing.

One on-line reference I found is:
http://www.wkpp.org/articles/Gear/newgeorge.html

Other reg design issues to think about are piston vs. diaphragm and sealed vs. unsealed. Again, DIR has a set of conclusions there, especially appropriate for situations when the water is not crystal-clear and warm, or if regs may be removed from bottles underwater.

The nice thing about it all is that as was pointed out, if you buy one of the better regs from a reputable manufacturer, you're probably in good shape for recreational diving...

 

[thethumper]

jeffsterinsf once bubbled...
I'm not sure I agree with all the conclusions about balanced vs. unbalanced, especially at recreational depths (less than 3-4 ATA of overpressure compared to a typical IP of about 10 ATA). I would think that the intermediate pressure would have to rise quite a bit to blow the valve open in a 1st stage. If the IP "suddenly" rose abroptly, I would think this to be the last thing you'd be worrying about in that case!

Be that as it may, there have been arguments in the DIR community that your secondary air source should be a lower-performing reg, apparently to help prevent it from free flowing.

One on-line reference I found is:
http://www.wkpp.org/articles/Gear/newgeorge.html

Other reg design issues to think about are piston vs. diaphragm and sealed vs. unsealed. Again, DIR has a set of conclusions there, especially appropriate for situations when the water is not crystal-clear and warm, or if regs may be removed from bottles underwater.

The nice thing about it all is that as was pointed out, if you buy one of the better regs from a reputable manufacturer, you're probably in good shape for recreational diving...

That's it Jeff.... Throw another wrench into it. :rofl:
I was wondering how long it would take for the circling DIR guys to take a bite.

I'm gonna throw a BIG non-DIR reg out there. The price has come down alot since the new distributor took over. Poseidon. People can say what they will about them, but when it comes down to it they will all admit that Poseidon has set the pace for regulators since it was the 1st single hose regulator ever produced.

It is a balanced pison 1st & 2nd stage & delivers more air @ depth than any other reg on the market.

<insert bulls eye here>

 

[jeffsterinsf]

No bullseye needed -- I'm not pro or con DIR, though I feel it very important to understand the opinions and the thought processes behind them to make decisions appropriate for an individual's (or team's) situation.

Thanks for adding to the wealth of information available here!

 

[jonnythan]

thethumper once bubbled...
Poseidon. People can say what they will about them, but when it comes down to it they will all admit that Poseidon has set the pace for regulators since it was the 1st single hose regulator ever produced.

It is a balanced pison 1st & 2nd stage & delivers more air @ depth than any other reg on the market.

First, whatever anyone can say about the Odin/Jetstream, I don't like the way it breathes.

Second, what difference does it make if a regulator can 'deliver' 6 times as much air as I can possibly breathe vs 3 times as much?

Have you *ever* pressed the purge on a Jetstream? There's no excuse for a regulator causing pain and extreme discomfort while purging.

I also don't like the side exhaust design at all. I was donated a Jetstream while horizontal on my left side during something of a drill. I was out of air for a few *more* seconds, as I had to rotate my head 90 degrees, then press the horribly designed purge to blow out my tonsils and clear the water from the reg. Absurd.

No Poseidon for me. They give tons of air, sure, but why would you even need that much? It's not at all natural.

 

[thethumper]

Don't get me wrong jeff, I really like alot of the theories dehind DIR. I use alot of there rigging. I just like giving DIR guys a tuff time every now & then. If you had a set of Odin/Jet Streams & dove them for awhile, you would understand were alot of us Poseidon guys were coming from. The man. purge I don't know that I've ever had to use it while UW. I use a 1/2 breath to clear it. Now yes the exhaust end of the 2nd stage does need to be pointing slightly in the down position. once you figure that... You don't even think about it. Kinda like adding or removing ait from you Wing.