Balanced vs. unbalanced - How is this related to Piston/diaphragm?

[neve]

Hi,

Another clueless rookie with a life-and-death question here.

I'm looking at buying a budget reg, and had my mind set on Oceanic SP4 until I wrote to my LDS and got this reply:

Hi (neve),
You can find our prices on our web site at (censored) for
this equipment. It is better you come down and discuss exactly what you do need. For example do you know that the Oceanic SP4 regulator is unbalanced and that for a little bit more you can obtain much better performance. Whatever you decide I promise you the best price for your equipment

Regards

(name)

My LDS is probably just trying to make more money by selling me a more expensive reg, but I'm interested to know why I should fork out an extra $100 for a balanced reg (in this case the Oceanic CDX).

I sort of understand the difference between balanced and unbalanced regs, but if I'm not planning to go deeper than 40m (130ft), an unbalanced reg will still perform the same way, won't it? How deep can you go before it gets more difficult to draw air on an unbalanced reg?

Diaphragm vs. Piston
Now this is the part that I can't even pretend to understand. What is the relevance of these mechanisms to balanced/unbalanced regs? I did some net research, but the things I read there just confused me even further.

I'm on a tight budget, so I'll still buy the SP4 unless somebody can convince me to splurge on a supposedly "better" reg.

Your help is very much appreciated.

 

[ymy]

Hi neve,

Not sure if you have seen this page.

http://www.diverlink.com/gear/regulatorfirststage.htm

It gives a pretty good description of the difference between balanced and unbalanced.

The difference between a diaphragm and piston, is instead of the piston moving back and forth, a diaphragm is put in its place.

For recreational diving, in warm water like Malaysia and S'pore I doubt one could tell the difference.

The added advantage of a simple piston (in addition to cheaper initial outlay) is ease of servicing .... less parts etc.

 

[neve]

Yes ymy I have tried to read and understand that article, but it didn't tell me at which depth the reg "acts up" and it gets more difficult to draw air.

And I still don't understand the relationship between balanced/unbalanced reg and diaphragm/piston. Are the used simultaneously or do they have nothing to do with each other?

I may do some cold water diving in the future, but not deep dives. Will my choice to buy balanced/unbalanced, piston/diaphragm regs matter in cold water diving?

Thanks again!

 

[ElectricZombie]

Even at depths of 130', you would notice a difference between a balanced and unbalanced reg. The balanced would breath easier. If the difference between a balanced and unbalanced is only $100.00, get the balanced. If you ever get into more advanced diving, you won't have to upgrade your equiptment. Balanced Piston type regs are more resistant to flooding, and to me, are easier to service. Balanced Diaphrams are good too but, I just prefer Pistons. By the way, I also prefer ScubaPro regulators.

 

[nickjb]

In the Divernet test the chaps dived (dove) to 40m+ (130ft) and concluded the Alpha 7 was the best breather. It also easily passed on the breathing machine. The full test is here. After reading this I expect you will buy the Alpha. I very nearly did

http://www.divernet.com/equipment/0401regtest.htm

 

[barb]

There is a thread on this site discussing the piston/diaphram question.
I dive in cold water mostly so I chose a sealed diaphram (less - no chance of the reg freezing up) Also a sealed 1st stage is better in contaminated (large algae blooms?) water.
I bought Apeks or my second choice would be Aqualung/U.S.Divers

 

[nickjb]

Does your extra $100 buy you Apeks? Not sure of US prices but over here a set of TX40s isn't much more expensive than a budget option. They will happily go deeper and colder than you will

 

[ymy]

Neve,

Let me try a shot at summarizing. I know it can be confusing. Basically there are 3 fundamental types out there (of course someone will come up with a hybrid model).

1. Unbalanced pistion. THis simplest mechanically. Least parts
2. The Balanced piston.
3. The balanced diaphragm. As someone said, I think there is no such thing as an unbalanced diaphragm.

The major difference between the balanced and unbalanced is ease of breathing at depth AND when your tank is low. Frankly, I can't tell the difference. I think the difference between manufacturers and models makes a bigger difference.

The difference between a diaphragm and piston is that water does not get into the moving parts in diaphragms. This eliminates freezing and jamming due to crud in your moving parts. However, I believe some manufaturers have designed environmentally sealed pistons also ...

My personal take is the difference is similar to the difference between a normal internal combustion engine and one with dual carbs or overhead cams etc. Is there a difference ? Yes. Can the majority of drivers tell the difference ... probably not.

 

[redacted]

Unbalanced regs (1st or 2nd stages) tend to be lower end systems but WOB differences may be hard to detect by a diver under normal conditions. If I let the tuning slip on my Mk20/G500(both balanced), it can actually breath harder than my Mk2/R190 (both unbalanced). With both tuned for peak performance, it's pretty hard for me to tell the difference, until I have to challange them. If you have to work hard (like swim against a current) or some other difficult situation (like an OOA diver) then the difference becomes readily apparent. And it is mostly because the high end balanced systems not only breath a little easier, but because they are able to deliver a much greater volume of air. Therein lies the biggest benefit of high end systems.

 

[neve]

HI all, thanks for the replies.

Electric Zombie: What do you mean by more "advanced" diving? I will probably go only as deep as 130ft or less.

nickjb: yes that article convinced me to buy Oceanic

barb: yes I ahve been following that thread, but none of the posts there answered my question.

ymy: Thanks for that. I think I got it now. Which one of the three types of reg are you using now? If you're in Malaysia, your 'playground' will likely be similar to mine

awap: thanks! that's a great example. At least now I know why I want to spend an extra $100 on the Oceanic CDX.