Looking for a great 1st regulator!! HELP :)

[halocline]

I think you need two diaphragms for the over-balanced regs. The regular diaphragm is exposed to ambient on the outside where the mainspring is. Unless I'm not seeing things correctly, it doesn't matter what diameter that is; it's just ambient pushing against the IP chamber. But, if you add a second external diaphragm for environmental sealing, connecting it with a piston (or sealed liquid) to the first diaphragm, and increase the size of the external diaphragm, the increase in size transfers the added pressure to the internal diaphragm.

I think that's right, anyhow.

Then there's the SP definition of "overbalanced" in which the MK 25 piston shaft is supposedly slightly flared at the end to negate any drop in IP that occurs as a result of the thickness of the piston edge exerting downstream pressure on the piston. This is actually a more accurate use of the term "overbalanced." The diaphragm design should be called "over depth compensating" because it has to do with the regulator's response to depth changes, not tank pressure changes. But that doesn't have the same marketing appeal, does it?

 

[herman]

While most OB regs do use 2 diaphrams, one for the primary diaphgram and the other as an enviromental seal, it is not a requirement that there be 2 diaphrams, all that matters is the one that is exposed to ambient pressure be larger than is necessary for the 1:1 ratio. If you think about it for a minute, since the 2 diaphrams are connected with a solid rod, in effect they are actually 1. The outer pushes directly on the inner one with a solid rod so any pressure on the outer one is directly transfered to the inner one which in turn transfers the force to the push pin. The space between is dead air space and while it will compress a little and transfer a little bit of force, the rod is the major contributor. Look at the diameter of any non OB regs diaphram, you will find they are all very close to the same diameter reguardless of make or model. The exposed (working) surface area is very close to 1 inch......If they were not, the 1:1 ratio of ambient pressure increase to IP increase would not be possible. The change in ambient is PSI....pounds per square inch. If you change the area (square inches) of the diaphram, you change the pounds per square inch of force excerted by the diaphram. More force means more pressure assisting the main spring and therefore more IP.


I agree with you on balanced vs depth compensated, this really is depth compensation we are discussing but this is deep enough without getting into word games.....and way more than I suspect the OP wanted to know.

 

[c5diver]

i like the diaphram 1st stage. i have scubapro mk17/s600 and mares mr42t/carbon 42. nice feature of the mares first stage is you can add the cold water dry kit later on down the road. my wife dives the proton and loves it. as mentioned earlier world wide service is no problem. the scubapro setup is nice but i don't think it breaths as easy.

 

[halocline]

While most OB regs do use 2 diaphrams, one for the primary diaphgram and the other as an enviromental seal, it is not a requirement that there be 2 diaphrams, all that matters is the one that is exposed to ambient pressure be larger than is necessary for the 1:1 ratio.

I don't think so, Herman. What has to be is that the area on the outside surface (ambient) is larger than on the inside surface (IP). I think we agree of this. Otherwise, any increase in ambient is simply matched by an equal increase in IP on the other side of the diaphragm. I don't see how you can have different surface areas on two sides of the same diaphragm; you need two different diaphragms to achieve that.

When you say that the diaphragm exposed to ambient must be "larger than is necessary for the 1:1 ratio" what must it be larger than? My answer would be it has to be larger than the area of IP pushing back against it; correct? Well, that's the interior surface of the diaphragm, and for the exterior to be larger than 1:1 I don't see how you can do it unless you have two different size diaphragms.

 

[TB2Scuba]

What about the HOG D1 regulators? Are they pretty good? I have noticed the name floating around the board just didn't know much about them.

 

[carrielsal]

What about the HOG D1 regulators? Are they pretty good? I have noticed the name floating around the board just didn't know much about them.

I own Apex XTX200's for my tech regs. A couple of weeks ago I used a buddy's hogs on a 105' dive. I did not think they breathed nearly as easy as my Apex's at that depth.
Apex has a WOB chart for the XTX200's, but I have never seen one for the hog regs. It would be interesting to see.

 

[CaveMD]

HOG D1

It's one of the better regs on the market right now, price is unbeatable for what you're getting.

HOG sells the service kits for them to service yourself

TDI offers a class for servicing them yourself, so far as I know Edge/HOG is the ONLY company that offers this.

If you plan to continue your diving into the tech relm, you only have to buy the regs once.

 

[CaveMD]

I own Apex XTX200's for my tech regs. A couple of weeks ago I used a buddy's hogs on a 105' dive. I did not think they breathed nearly as easy as my Apex's at that depth.
Apex has a WOB chart for the XTX200's, but I have never seen one for the hog regs. It would be interesting to see.

Did you try the 2nd stage adjustments or just leave them as they were? Makes quite a difference

antsi results
http://www.scubaboard.com/forums/edge-gear/309166-hog-bal-second-hog-d1-antsi-results.html

 

[herman]

I don't think so, Herman. What has to be is that the area on the outside surface (ambient) is larger than on the inside surface (IP). I think we agree of this. Otherwise, any increase in ambient is simply matched by an equal increase in IP on the other side of the diaphragm. I don't see how you can have different surface areas on two sides of the same diaphragm; you need two different diaphragms to achieve that.

When you say that the diaphragm exposed to ambient must be "larger than is necessary for the 1:1 ratio" what must it be larger than? My answer would be it has to be larger than the area of IP pushing back against it; correct? Well, that's the interior surface of the diaphragm, and for the exterior to be larger than 1:1 I don't see how you can do it unless you have two different size diaphragms.

This is getting way into reg design but let me see if I can reduce it some. IP= spring pressure (constant) + diaphram force. Diaphram force change is equal to the ambient pressure change times the surface area of the diaphram. As you decend the force added to the equasion by the diaphram is increased. If for example, the diaphram is 1 square inch (and most are ....side note... measure the working surface diameter of any diaphram reg, you will find it to be about 1.15 inches.....(1.15/2)*2 x 3.1416= guess what...1 square inch ) and you decend 2 ft to increase the ambient pressure by 1 psi the increase in IP will be 1 psi. (1 inch sq x 1 psi) = 1 lb of additional force on the diaphram which results in an additional 1 psi of IP. For easy math, increase the diaphram area to 2 square inches. Decend 2 ft so we have another 1 psi increase in ambient pressure. The increase is now 2 in sq x 1 psi = 2 lbs of additional force on the diapharm and an additiona 2 psi of IP. We now have a 2 psi shift in IP instead of a 1 psi shift for the same depth change or in other words, our special reg is way overbalanced ( or as we both agree, over depth compensated). The actual size (working surface) of the enviromental seal/diaphram on OB regs is in the 1.35 inch range....do the math and it works out to about an extra 15 psi at 100 ft.

 

[carrielsal]

Did you try the 2nd stage adjustments or just leave them as they were? Makes quite a difference

antsi results
http://www.scubaboard.com/forums/edge-gear/309166-hog-bal-second-hog-d1-antsi-results.html

It was the one and only time I have tried a hog reg. I had been diving non-stop for several days in a row and now I no longer remember if I tried adjusting the second stage. I had heard such good things about them that it surprised me.