Piston or Diaphragm

[Lorenzoid]

The water pressure is exerted on the piston through the holes in the cap. Many folks are confused by the balanced vs depth compensating thing.

My understanding is that "balanced" refers to the ability of a reg to minimize IP decrease as tank pressure decreases. Is there another use of the term "balanced" that I'm not familiar with?

My understanding is that ALL regs adjust IP in response to depth, such that the IP equals the fixed value (e.g., 135 PSI) that is established by the spring plus ambient water pressure. I'm not familiar with the term "depth-compensating," other than in this context. Is there some other parameter besides IP that some regs adjust in response to depth?

I'm sure you guys know more about regs than I do, and the confusion is over terminology. Seemed like an interesting conversation, so I'm following it.

 

[Superlyte27]

I think that what I'm discovering is that a very large group of people have no idea how these things really work, perhaps even the people who make and work on these regulators. I'm uncertain which group I'm in.


-edit-
See articles like these just add to my confusion. In the first two paragraphs it says exactly what I've always been taught.
http://scuba.about.com/od/equipment/a/BalancedRegDefinition.htm

 

[eeel]

My understanding is that "balanced" refers to the ability of a reg to minimize IP decrease as tank pressure decreases. Is there another use of the term "balanced" that I'm not familiar with?

My understanding is that ALL regs adjust IP in response to depth, such that the IP equals the fixed value (e.g., 135 PSI) that is established by the spring plus ambient water pressure. I'm not familiar with the term "depth-compensating," other than in this context. Is there some other parameter besides IP that some regs adjust in response to depth?

I'm sure you guys know more about regs than I do, and the confusion is over terminology. Seemed like an interesting conversation, so I'm following it.

Lorenzoid,

You are correct here, except rebreathers that have a constant mass flow orifice need to have a non depth compensating first stage. This is usually done by installing a blanking plug across the ambient chamber on a diaphragm first stage. This now does limit the depth the reg will deliver gas at, typically around 300 feet. Rebreather divers that use these type of depth limited first stages have all kinds of ingenious solutions to allow them to dive deeper.

 

[elan]

They were probably confused.

Almost all regs are depth compensating (except those diaphragm regs with a plug installed that are used by rebreather folks)

the reason why your DS would be slowly inflatin is that most DS regs use lower IP and at depth where the argon or air are very dense the regs just cannot provide enough flow. Low IP(70 psi or so) plus high density plus big volume of the DS takes it long to inflate)

some piston regs (mk25) have a higher flow rate than diaphragms.

I think that what I'm discovering is that a very large group of people have no idea how these things really work, perhaps even the people who make and work on these regulators. I'm uncertain which group I'm in.


-edit-
See articles like these just add to my confusion. In the first two paragraphs it says exactly what I've always been taught.
http://scuba.about.com/od/equipment/a/BalancedRegDefinition.htm

 

[Superlyte27]

I'm sure you guys know more about regs than I do, and the confusion is over terminology.

LOL, I'm not so sure about that. Honestly, I'm not sure of anything. I can find official looking articles stating the opposite of each other. LOL... must be a reason I quit rebuilding regs for a living.

---------- Post added July 16th, 2013 at 06:19 PM ----------

Lorenzoid,

You are correct here, except rebreathers that have a constant mass flow orifice need to have a non depth compensating first stage. This is usually done by installing a blanking plug across the ambient chamber on a diaphragm first stage. This now does limit the depth the reg will deliver gas at, typically around 300 feet. Rebreather divers that use these type of depth limited first stages have all kinds of ingenious solutions to allow them to dive deeper.

This I am completely familiar with.

---------- Post added July 16th, 2013 at 06:20 PM ----------

They were probably confused.

Almost all regs are depth compensating (except those diaphragm regs with a plug installed that are used by rebreather folks)

the reason why your DS would be slowly inflatin is that most DS regs use lower IP and at depth where the argon or air are very dense the regs just cannot provide enough flow. Low IP(70 psi or so) plus high density plus big volume of the DS takes it long to inflate)

some piston regs (mk25) have a higher flow rate than diaphragms.

I never bought a DS Reg, always just used my SP5.

 

[elan]

SP5 is still a low flow reg to push air or argon at 300 ft

 

[kelemvor]

I had just read about this in the NAUI Master Scuba Diver manual. According to that book, "balanced" refers only to the first stage regulator's ability to keep IP constant with varying cylinder pressure. The book goes on to say:

In all scuba regulators, external pressure is admitted into the spring chamber and contributes to the spring pressure. Thus, the intermediate pressure remains at a constant above the ambient pressure as the diver descends or ascends.

Emphasis mine. My guess is that if you've got one where the IP is varying at depth it's either defective or specifically designed that way for some purpose.

There's several pages of material on the subject in the book.

The book goes go on to say that formerly diaphragm regulators were preferred for dirty water conditions because they were sealed preventing water from getting into the inner workings of the reg. It mentions that several manufacturers have modern piston regs that are also sealed and provide the same feature.

As best I can tell there's no great reason to prefer one design over the other specifically. Maybe freezing cold water is an important factor here?

 

[Lorenzoid]

. . .
See articles like these just add to my confusion. In the first two paragraphs it says exactly what I've always been taught.
Balanced Regulators - What Is a Balanced Scuba Regulator?

That article sure does seem to say that the term "balanced" has some relation to depth in addition to tank pressure. I'm not sure I trust about.com as an authoritative source. Have you read Regulator Savvy?--great book for understanding regulators. It doesn't go into exotic stuff like regs for rebreathers, though.

 

[Superlyte27]

I actually read at least 7 or 8 different articles. Honestly, I'm not trusting any of them. They are about 50/50. I quit caring. Here's what I do know.... my SP5 suck to breath on the deeper I get. I can't understand how pressure increases on the piston because the airspace on the other side of the piston is so much smaller. But, I will concede that I really don't know.

But, talking to several Oceanic repair techs, I'm convinced that lots of people don't know. At least I'm not alone.
I called 4 people who don't know each other, who have been working on Oceanic for decades, and they all told me that the SP5 only puts out 140psi, regardless of depth.

I would love to test this, but I don't have anything I can build a pressure pot out of (yet).

 

[robertarak]

While you guys are all arguing to prove who is smarter, the OP is trying to get some answers...

Sorry about that yes I am looking at a balanced piston. My LDS is an atomic dealer and I have used them and it seemed to work very well. The ST1 is what I am considering. One other thing that concerns me is service. I notice that I am having an issue with finding service material for that as well as the neccessary tools to work on them. I am just one of those people that likes to know how to work on my own equipment.

The Atomic regulator are excellent. I have and use many. If you are going to be wanting to service your own regs I highly suggest you look at the HOG regs. HOG is the only manufactures that allows users to service their own regs once they complete a HOG regulator Service Class. I dive, sell, and service HOG regs as well as teach the HOG Regulator Service Class. I will be happy to answer any question you might have.