constant IP regs, piston vs diaphragm

OceanOpportunity · 14th February 2007, 01:53

Hey gang,

working on a mCCR design. I am familair with plugging the Apeks/Zeagle diaphragm 1st to obtain a constant IP. Has anyone modified a piston reg by custom machining the section of the reg body without the ambient holes?

**wedivebc** · 14th February 2007, 02:38

Quote: (Originally Posted by OceanOpportunity)

Hey gang,

working on a mCCR design. I am familair with plugging the Apeks/Zeagle diaphragm 1st to obtain a constant IP. Has anyone modified a piston reg by custom machining the section of the reg body without the ambient holes?

Only problem with that is many piston regs use shims to adjust IP. When setting up a mCCR for your personal inspiration rate you might find a screw adjustable IP is easier to work with.

abowie · 14th February 2007, 04:53

What he said.

In addition many piston firsts (like Scubapro ones) have many holes into the ambient chamber. One leak and suddenly your O2 injection rate shoots up!

If I was doing it, I'd stick to blanking off a diaphragm reg.

wizbang · 14th February 2007, 05:13

Tubby and a few others made a simlar machined cap for the poseidon Cyklon first stage.

But for me i would stick with the blanking plug for the Apeks and Zeagle first stages.

Crazyduck · 16th February 2007, 22:04

Has anyone-
Yes, the MK15 series used a simple Sherwood design.
(If my memory is not failing me.)

Steam Machines does purchase a Scubapro Piston regulator but….
They do all kinds of things to it include putting in Pillar valves on the tank.

Just as a side thought- some of those ‘simple’ piston regulators are not ‘simple’ any more.

My vote is for the apex with plug and 1st stage overpressure valve.

Zen thought of the day- why build a nuclear reactor when a wind turbine will do?

Good luck mate, Andrew

**Dave Sutton** · 17th February 2007, 03:31

Quote: (Originally Posted by OceanOpportunity)

Hey gang,

working on a mCCR design. I am familair with plugging the Apeks/Zeagle diaphragm 1st to obtain a constant IP. Has anyone modified a piston reg by custom machining the section of the reg body without the ambient holes?

To paraphrase the others: Why bother? Adjustment of the IP in 5 PSI increments is a need for getting the orifice flows right for a KISS or similar feed system. A diaphram reg only needs an allen key to be adjusted, while a piston needs to be disassembled and then using trial and error needs to have shims added and removed. Pain in the neck and not field adjustable. Stick to what works. Any diaphram regulator would work fine, the reason we like the Apeks is due to the ease of mechanical installation of the plug into their environmental cap.

Dave

scubagrunt · 17th February 2007, 06:22

I agree with why change things that seem to work. that being said, scubapro does make a piston reg that is adjustable without adding shims. "Mk 25" uses an allen key to adjust, if my memory serves me correctly. But it is sure easier to use a apex (or zeagle) dry seal reg.

marekm · 17th February 2007, 09:13

Another problem with the Scubapro MK25 regs when using them with a KISS valve is that the IP cannot be adjusted while the reg is pressurized (or at least that is what the manual says, I have not tried it for fear of damaging the piston or seat). Anyway, this means you have to turn off the tank and release the pressure from the reg first, then turn the allen key a bit, before repressurising the first stage and measuring the IP again. As you can imagine this is an annoying way to precisely set the IP.

Furhermore, Scubapro MK25's with Allen key adjustable IP have an inverse system to balanced diaphragm regs such as the Mares MR12. So if the hex bolt is completely removed, the IP is at max pressure (around 15bar on my regs). As you screw the bolt in, the IP keeps getting lower.

Silent · 17th February 2007, 12:49

Quote: (Originally Posted by marekm)

Another problem with the Scubapro MK25 regs when using them with a KISS valve is that the IP cannot be adjusted while the reg is pressurized (or at least that is what the manual says, I have not tried it for fear of damaging the piston or seat). Anyway, this means you have to turn off the tank and release the pressure from the reg first, then turn the allen key a bit, before repressurising the first stage and measuring the IP again. As you can imagine this is an annoying way to precisely set the IP.

You don't 'have' to depressurise the 1st stage to adjust the IP, just purge a reg attached to the MK25 so the piston knife edge is not in contact with the HP seat, thus there should be no risk of cutting or engraving the HP seat.

**jmurba** · 17th February 2007, 13:52

Quote: (Originally Posted by wedivebc)

Only problem with that is many piston regs use shims to adjust IP. When setting up a mCCR for your personal inspiration rate you might find a screw adjustable IP is easier to work with.

if you use an orifice as restrictor you would hav a problem, but if you use a needle valve you will b abl to adjust the flow rate using the regular 11 bars ip

14th February 2007, 01:53	#1 (permalink)
OceanOpportunity for a world of water Current Rebreather/s: Other CCR Dolphin Home Build Other Rebreather/s: Not Bought Yet Inspiration Classic Other CCR Dolphin Home Build Join Date: Nov 2006 Location: Providence, RI USA Posts: 598	constant IP regs, piston vs diaphragm Hey gang, working on a mCCR design. I am familair with plugging the Apeks/Zeagle diaphragm 1st to obtain a constant IP. Has anyone modified a piston reg by custom machining the section of the reg body without the ambient holes? __________________ Michael Lombardi Oceans of Opportunity www.oceanopportunity.com Elected Director, Society for Human Performance in Extreme Environments MN'07, The Explorers Club Project Manager, Diving a Dream
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14th February 2007, 02:38	#2 (permalink)
wedivebc Dave Tomblin Current Rebreather/s: Megalodon Other CCR Other Rebreather/s: Not Bought Yet Inspiration Classic Sport Kiss Other CCR Join Date: Feb 2005 Location: Vancouver Island BC Canada Posts: 1,510	Re: constant IP regs, piston vs diaphragm Quote: (Originally Posted by OceanOpportunity) Hey gang, working on a mCCR design. I am familair with plugging the Apeks/Zeagle diaphragm 1st to obtain a constant IP. Has anyone modified a piston reg by custom machining the section of the reg body without the ambient holes? Only problem with that is many piston regs use shims to adjust IP. When setting up a mCCR for your personal inspiration rate you might find a screw adjustable IP is easier to work with. __________________ Cheers, Dave.... Man is the only animal burdened with the knowledge he will eventually die
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14th February 2007, 04:53	#3 (permalink)
abowie Fighting Girl Current Rebreather/s: Sport Kiss Other Rebreather/s: Join Date: May 2005 Location: Land of Oz Posts: 574	Re: constant IP regs, piston vs diaphragm What he said. In addition many piston firsts (like Scubapro ones) have many holes into the ambient chamber. One leak and suddenly your O2 injection rate shoots up! If I was doing it, I'd stick to blanking off a diaphragm reg. __________________ Andrew Bowie Rebreather-friendly Buddy
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14th February 2007, 05:13	#4 (permalink)
wizbang WEB MERMEN Current Rebreather/s: Inspiration Classic Dolphin Home Build Other Rebreather/s: Not Bought Yet Inspiration Vision Evolution Prism Topaz Sport Kiss Classic Kiss Dolphin Home Build Join Date: Feb 2005 Location: Perth Australia Posts: 386	Re: constant IP regs, piston vs diaphragm Tubby and a few others made a simlar machined cap for the poseidon Cyklon first stage. But for me i would stick with the blanking plug for the Apeks and Zeagle first stages.
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16th February 2007, 22:04	#5 (permalink)
Crazyduck Underwater Mechanic Current Rebreather/s: Dolphin Other Rebreather/s: Dolphin Join Date: Mar 2005 Location: TEXAS, Dallas/ Ft.Worth Posts: 720	Re: constant IP regs, piston vs diaphragm Has anyone- Yes, the MK15 series used a simple Sherwood design. (If my memory is not failing me.) Steam Machines does purchase a Scubapro Piston regulator but…. They do all kinds of things to it include putting in Pillar valves on the tank. Just as a side thought- some of those ‘simple’ piston regulators are not ‘simple’ any more. My vote is for the apex with plug and 1st stage overpressure valve. Zen thought of the day- why build a nuclear reactor when a wind turbine will do? Good luck mate, Andrew __________________ Howdy Senor- What’s Happening! Rob Davie April 2005- Presently in a state of transition from Open Circuit to Closed Circuit. "You will not be punished for your anger; you will be punished by it." - Buddha.
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17th February 2007, 03:31	#6 (permalink)
Dave Sutton Diveshop of Horrors Current Rebreather/s: Sport Kiss MK 15.X rEvo Other CCR Azimuth Home Build Other Rebreather/s: Evolution Megalodon rEvo Other CCR Azimuth Home Build Join Date: Jun 2006 Location: Narragansett, Rhode Island and Hackettstown, New Jersey Posts: 2,913	Re: constant IP regs, piston vs diaphragm Quote: (Originally Posted by OceanOpportunity) Hey gang, working on a mCCR design. I am familair with plugging the Apeks/Zeagle diaphragm 1st to obtain a constant IP. Has anyone modified a piston reg by custom machining the section of the reg body without the ambient holes? To paraphrase the others: Why bother? Adjustment of the IP in 5 PSI increments is a need for getting the orifice flows right for a KISS or similar feed system. A diaphram reg only needs an allen key to be adjusted, while a piston needs to be disassembled and then using trial and error needs to have shims added and removed. Pain in the neck and not field adjustable. Stick to what works. Any diaphram regulator would work fine, the reason we like the Apeks is due to the ease of mechanical installation of the plug into their environmental cap. Dave __________________ "Silent Diving with No Bubbles and No Politics".... www.nobubblediving.com
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17th February 2007, 06:22	#7 (permalink)
scubagrunt CCR Diva Current Rebreather/s: Inspiration Classic Megalodon Classic Kiss Optima rEvo Other CCR Other SCR Other Rebreather/s: Not Bought Yet Inspiration Classic Inspiration Vision Evolution Megalodon Sport Kiss Classic Kiss Optima rEvo Other CCR Other SCR Join Date: May 2005 Location: Washington Posts: 441	Re: constant IP regs, piston vs diaphragm I agree with why change things that seem to work. that being said, scubapro does make a piston reg that is adjustable without adding shims. "Mk 25" uses an allen key to adjust, if my memory serves me correctly. But it is sure easier to use a apex (or zeagle) dry seal reg. __________________ "No good deed goes unpunished!" www.silentscuba.com
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17th February 2007, 09:13	#8 (permalink)
marekm Banned Current Rebreather/s: Not Bought Yet Other Rebreather/s: Not Bought Yet Join Date: Oct 2006 Location: Brisbane, Australia Posts: 196	Re: constant IP regs, piston vs diaphragm Another problem with the Scubapro MK25 regs when using them with a KISS valve is that the IP cannot be adjusted while the reg is pressurized (or at least that is what the manual says, I have not tried it for fear of damaging the piston or seat). Anyway, this means you have to turn off the tank and release the pressure from the reg first, then turn the allen key a bit, before repressurising the first stage and measuring the IP again. As you can imagine this is an annoying way to precisely set the IP. Furhermore, Scubapro MK25's with Allen key adjustable IP have an inverse system to balanced diaphragm regs such as the Mares MR12. So if the hex bolt is completely removed, the IP is at max pressure (around 15bar on my regs). As you screw the bolt in, the IP keeps getting lower.
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17th February 2007, 12:49	#9 (permalink)
Silent Staying Silent! Mostly... Current Rebreather/s: Other CCR Other Rebreather/s: Megalodon Ouroboros Other CCR Join Date: Jun 2005 Location: Northants, UK Posts: 383	Re: constant IP regs, piston vs diaphragm Quote: (Originally Posted by marekm) Another problem with the Scubapro MK25 regs when using them with a KISS valve is that the IP cannot be adjusted while the reg is pressurized (or at least that is what the manual says, I have not tried it for fear of damaging the piston or seat). Anyway, this means you have to turn off the tank and release the pressure from the reg first, then turn the allen key a bit, before repressurising the first stage and measuring the IP again. As you can imagine this is an annoying way to precisely set the IP. You don't 'have' to depressurise the 1st stage to adjust the IP, just purge a reg attached to the MK25 so the piston knife edge is not in contact with the HP seat, thus there should be no risk of cutting or engraving the HP seat.
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17th February 2007, 13:52	#10 (permalink)
jmurba wet bear Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: May 2006 Location: cannes france Posts: 925	Re: constant IP regs, piston vs diaphragm Quote: (Originally Posted by wedivebc) Only problem with that is many piston regs use shims to adjust IP. When setting up a mCCR for your personal inspiration rate you might find a screw adjustable IP is easier to work with. if you use an orifice as restrictor you would hav a problem, but if you use a needle valve you will b abl to adjust the flow rate using the regular 11 bars ip __________________ when will I be able to think about something else then spending hours underwater, when will I be normal ? http://web.mac.com/jmurba/Site_2/home.html http://web.mac.com/jmurba/Site_3/home.html
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