Overbalance reg = hype?

[ae3753]

Currently diving Zeagle DS-IVs. Great reg, and similar design to the Apeks DS4 except that Zeagle has a different HP seat and the Apeks "overbalances". At least that's my understanding from searching the board and reading marketing the brochures.

So is overbalancing hype? And would someone notice the difference at recreational depths?

We'll see if we can borrow someone's Apeks regs, but in the meantime, interested in people's experiences.

Thanks.

-Don

 

[jonnythan]

As I understand it, it might make a difference when diving deep on a dense gas mix like air or nitrox.

Since air gets thicker at deep depths, it can get harder to breathe.. so these regs increase the IP with depth to keep the work of breathing even.

AFAIK, for recreational depths, there is no difference at all.

 

[Diver0001]

I think it's hype. I have an overbalanced reg too (an Aqualung) and at any kind or recreational depths the difference it makes is bound to be minuscule.

What I think is that they made a design error and instead of fixing it they thought of a way to market it as a feature.

R..

 

[dannobee]

I have an ATX200 with an ATX50 octo and Suunto 'puter that I'll let you try sometime when I'm in Monterey. It's DIN, but I can switch it back to yoke.
Dan

 

[DA Aquamaster]

Hype, at least in that use of the term.

Increasing IP at depth any more than needed to match the increase in ambient pressure would at best be a crutch for a poor perfroming regulator. Gases do get thicker at the higher IP's needed at depth, but not by as much as you would think and if it is enough to affect the performance of your regulator, your reg does not perform all that well to begin with. In short overbalancing is a poor substitute for latger air passages and a decent flow rate to begin with.

Overbalancing also causes a problem with second stage tuning as with an overbalanced first stage, the second stage needs to be set with a high enough inhalation effort to avoid a slight freeflow at depth where the difference between ambient pressure and IP is greater. This means that unless the second stage is adjustable, it will breathe harder at shallower depths.

The term "overbalanced" also has different meanings. Scubapro uses the term differently. In their definition overbalancing refers to the use of a slightly oversized seat carrier or piston stem to accommodate for the area of the seating edge on the orifice. This oversize stem or seat carrier results in true balancing of the first stage where there is no change at all in IP as tank pressure goes form full to empty. In the case of a first stage that does not use this form of "overbalancing" there will be a 4 to 6 psi change in pressure even in an otherwise "balanced" design.

 

[rescuediver009]

I think that it is a feature that can as mentioned adjust for a poor performing reg, but also it might make a great reg better. I don't think that you are missing out diving with a zeagle and not kick yourself for not having something ovebalanced. You may notice easier breathing with the apeks but I don't know if it is a fair comparison for either reg as one that is slightly tuned better, may have you convinced...

 

[Rick Murchison]

Hype, at least in that use of the term.
Increasing IP at depth any more than needed to match the increase in ambient pressure would at best be a crutch for a poor perfroming regulator.

Could you expand on that a little? I'm curious as to what you mean... the regs I know of that are overbalanced (overbalanced in the sense of increasing IP a little with depth) are the very best performers by anyone's measure, including machine measurements.

Gases do get thicker at the higher IP's needed at depth, but not by as much as you would think

Huh? Density increases are precise and measurable. What do you mean "not as much as you would think?" Increased density does affect the performance of your regulator, in precise and measurable ways - it's just physics.

In short overbalancing is a poor substitute for latger air passages and a decent flow rate to begin with.

Again, I think you've missed the point of overbalancing - which is to maintain as close to the same volume delivery (flow) rate as is possible while density changes. You either have to vary the size of the opening delivering the gas, a la ScubaPro, or vary the pressure of the gas through the same sized opening, a la Apeks. But you have to change something as density changes or you'll have flow changes too.

Overbalancing also causes a problem with second stage tuning

Now you have a valid point. Especially if you attach an older second stage to a new, overbalanced first, you're liable to have freeflow problems at depth. In my experience this is almost universal below about 165 feet.
But... I have had precisely zero problems with non-adjustable new second stages (Legends, in this case) and remarkably easy breathing throughout the range of surface to over 200 feet.
If you want to call it "hype" that's fine... it is "hype" that works well.
Rick

 

[PhilEllis]

Hype, at least in that use of the term.............

In short overbalancing is a poor substitute for larger air passages and a decent flow rate to begin with.

I think you are selling the "apeks" technology a little short here. You are correct that you can make a regulator breathe much easier by building "larger air passages and a decent flow rate" You can also make it breathe easier by permitting a design that increases the intermediate pressure to compensate for the loss of "relative" difference in pressure as ambient pressure increases (over-balanced). I think Apeks chooses the latter due to the primary difficulty of excessively large flow rates in cold water diving....first stage freeze-up. By reducing the flow rate of the first stage, Apeks provides additional insulation from freeze-up that would result if a high flow rate design goes into free-flow. They also restrict the movement of the purge button and lever to prevent excessive (more than necessary) purge volumes.

Overbalancing also causes a problem with second stage tuning as with an overbalanced first stage, the second stage needs to be set with a high enough inhalation effort to avoid a slight freeflow at depth where the difference between ambient pressure and IP is greater. This means that unless the second stage is adjustable, it will breathe harder at shallower depths.

In a poorly designed second stage, I would agree with you completely. However, with the "apeks" technology (apeks regulators and legend series regulators), we are not dealing with poorly designed second stages. We routinely send the non adjustable apeks and legend second stages out with IP lockups at 138 PSI and a static cracking effort as low as 0.9 inches of water. These regulators NEVER result in complaints about free-flows even at this low effort. This is, I think, the result in a good second stage design....not unique to apeks but still very good. As a note of interest, the apeks second stages with static cracking efforts as low as 0.9 inches of water require only 1.6 inches of water to remain open (with no venturi effect activated) even at very high flow rates (22 SCFM).

Hype, at least in that use of the term.............

I am certainly not a regulator expert, but I have concluded that, with regard to the "apeks" technology, over-balanced is not hype. Our divers love them and they are the ONLY line we sell that result in ZERO between-service complaints. Thanks.

Phil Ellis
Dive Sports Online
www.divesports.com
(800) 601-DIVE

 

[oxyhacker]

Apeks calls it overbalancing when the IP increases with depth. Since all Apeks 2nds are balanced this doesn't cause problems with the 2nds freeflowing as the IP increases, though it might possibly with non-Apeks 2nds used on overbalanced Apeks 1sts. Oddly enough, when RSD tested some regs a few years back, their entry level Apeks 1st, which is not drysealed and hence not overbalanced (overbalancing on the Apeks 1sts is a byproduct of the drysealing cold water system) slightly outperformed the balanced version!

Scubapro, on the Mk20/25 at least, calls it overbalancing when the IP increases as the tank pressure drops. Not sure what they mean when they say the diaphragm 1sts are overbalanced - I have never found anyone at SP who could explain (DA?).

So I tend to agree that it is mostly just a buzzword, and that while it may be a useful thing if done right, it is hardly something to base a buying decision on. And you got to wonder if it may often not be just the manufacturer trying to put a good face on an accidental aspect of the design. I'd be really surprised if you can tell a difference between a Zeagle and an Apeks in breathing effort other than random differences in tuning and how long since they were serviced.

 

[pescador775]

The IP of the DA Aquamaster increases as tank pressure drops. This is the signature of an unbalanced first stage diaphragm valve. Dropping IP with decreasing tank pressure occurs with unbalanced piston valves. These are just factoids. I didn't know that the MK20 reg IP increased with falling tank pressure. I doubt if it is very significant.