rileymartin
Contributor
Can the old Scubapro MK200/G200 regulator be oxygen cleaned?
Oxygen clean old regulator
- Thread starter rileymartin
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halocline
Contributor
Yes, no problem.
Any regulator can be oxygen cleaned.
Finding the right O-rings and valves seats to build an oxygen compatable regulator that is a different matter. The criticle points are the locations in the regulator where the gas is at a high pressure and where it gets compressed, such as any 90 deg. angle ports and at valve to seat interfaces. It is usually the valve seat that is the most difficult to get oxygen compatable materials for.
Oxygen clean just means that the peice of equipment was cleaned of all oxygen contaminates like silicon grease, finger prints, etc. And then reassemble with oxygen compatable lubrication such as Cristo-lube.
To really be safe and to be able to use a unit with anything over about 40% oxygen in the mix, one has to re-build the unit with oxygen compatable parts like viton valve seats and the correct O-rings.
Get yourself a copy of the Oxyhacker book from Airspeed Press Homepage - Books For Serious Divers and educate yourself.
Finding the right O-rings and valves seats to build an oxygen compatable regulator that is a different matter. The criticle points are the locations in the regulator where the gas is at a high pressure and where it gets compressed, such as any 90 deg. angle ports and at valve to seat interfaces. It is usually the valve seat that is the most difficult to get oxygen compatable materials for.
Oxygen clean just means that the peice of equipment was cleaned of all oxygen contaminates like silicon grease, finger prints, etc. And then reassemble with oxygen compatable lubrication such as Cristo-lube.
To really be safe and to be able to use a unit with anything over about 40% oxygen in the mix, one has to re-build the unit with oxygen compatable parts like viton valve seats and the correct O-rings.
Get yourself a copy of the Oxyhacker book from Airspeed Press Homepage - Books For Serious Divers and educate yourself.
halocline
Contributor
He's not talking about the MK20, he's talking about the MK200. That reg is a predecessor to the MK2; it's an unbalanced piston reg, and I suspect is ideal for high O2 use in that there are no dynamic o-rings subject to HP gas, and the HP chamber is very simple and linear. The entire rebuild kit consists of 2 o-rings, a seat, and filter. If I were going to use one of my regs for 100% O2, I'd use my MK2.
OP
rileymartin
Contributor
I called my local Scubapro dealer to discuss bringing in the regulator for O2 service and they called Scubapro and I was told Scubapro said they do not make the O2 compatible seats and rings for the MK200. Does anyone have the resources to double-check if that's accurate?
Thanks.
Thanks.
halocline
Contributor
Another beauty from a dive shop.
Let's assume for the sake of argument that the seat/o-rings are the same as on the MK2. I'm not 100% sure they, but actually it doesn't matter. There are only three o-rings in the entire regulator, other than port plug o-rings. They are: 008, for the piston stem, 021 for the piston head, and 015 for the yoke nut seal. Go find viton o-rings in those sizes. The only difference with the MK200 might be a slightly larger piston head o-ring, but I'd be shocked if you couldn't get a viton o-ring to fit it.
That leaves the seat, which is just a teflon plug. It is a different part number than the MK2, but I'd be curious to see the difference.
Another thing is that personally I wouldn't even worry about viton o-rings. The important thing is to get rid of contaminants that could ignite and use O2-compatible lube; since the reg is only in contact with 100% O2 while in use, (a couple of hours/week, maybe?) the degradation of the o-rings is not going to be an issue, considering you'll rebuild/re-clean the reg on a regular basis.
Let's assume for the sake of argument that the seat/o-rings are the same as on the MK2. I'm not 100% sure they, but actually it doesn't matter. There are only three o-rings in the entire regulator, other than port plug o-rings. They are: 008, for the piston stem, 021 for the piston head, and 015 for the yoke nut seal. Go find viton o-rings in those sizes. The only difference with the MK200 might be a slightly larger piston head o-ring, but I'd be shocked if you couldn't get a viton o-ring to fit it.
That leaves the seat, which is just a teflon plug. It is a different part number than the MK2, but I'd be curious to see the difference.
Another thing is that personally I wouldn't even worry about viton o-rings. The important thing is to get rid of contaminants that could ignite and use O2-compatible lube; since the reg is only in contact with 100% O2 while in use, (a couple of hours/week, maybe?) the degradation of the o-rings is not going to be an issue, considering you'll rebuild/re-clean the reg on a regular basis.
OP
rileymartin
Contributor
Thanks, I guess I need to check with another shop and see if they're willing to see what will fit. The original shop I went to said I had to replace my first stage with... I forget now... either an MK2 or MK20 which they said Scubapro did have O2 cleaning kits for.
The Mk 20 Ntrox is the only reg SP specifically recommneds for 100% O2 use in the US and I suspect that has to do more with product liability concerns here than anything else.
Scubapro now uses EPDM o-rings in everything. The difference between nitrile rubber, EPDM and Viton o-rings is esentially ignition temp and the ignition temp gets higher in that order.
As for seat materials, a similar difference will exist in terms of ignition temps of various seat materials, but the o-rings will burn first, so it's a moot issue. The potential for degradation of seats and o-rings in a high O2 environment is often cited as a concern but the reality is that the average deco reg is just not exposed to high percentage of O2 that long between annal services and it's really more of a concern in regard to tank neck o-rings and valve seats where the exposure to high percentages of O2 is continuous and long term.
In particular the major difference between the Mk 200 and the later Mk 2 is the number of low pressure ports and if you properly clean the reg and replace all the original o-rings with the o-rings with EPDM o-rings from current annual service kits, it should be good to go as long as you take suitable precautions. As noted above, the seat materail is just not an issue.
The thing to remember is that anything will burn in a 100% O2 environment if the ignition temp is sufficiently high. So care should alwyas be taken to ensure that any potential for ignition is avoided such as entrained particles in the flow path, sharp edges in the flow path, or any rapid compression that could occur when pressurizing a closed system. Scuba valves and regs are not designed for O2 service and contain flow paths that are not well suited to O2 use, and most scuba valves come up to pressure very fast. So always turn the valve on very slowly with the purge slightly depressed to ensure the system is not closed when initially pressurized.
Scubapro now uses EPDM o-rings in everything. The difference between nitrile rubber, EPDM and Viton o-rings is esentially ignition temp and the ignition temp gets higher in that order.
As for seat materials, a similar difference will exist in terms of ignition temps of various seat materials, but the o-rings will burn first, so it's a moot issue. The potential for degradation of seats and o-rings in a high O2 environment is often cited as a concern but the reality is that the average deco reg is just not exposed to high percentage of O2 that long between annal services and it's really more of a concern in regard to tank neck o-rings and valve seats where the exposure to high percentages of O2 is continuous and long term.
In particular the major difference between the Mk 200 and the later Mk 2 is the number of low pressure ports and if you properly clean the reg and replace all the original o-rings with the o-rings with EPDM o-rings from current annual service kits, it should be good to go as long as you take suitable precautions. As noted above, the seat materail is just not an issue.
The thing to remember is that anything will burn in a 100% O2 environment if the ignition temp is sufficiently high. So care should alwyas be taken to ensure that any potential for ignition is avoided such as entrained particles in the flow path, sharp edges in the flow path, or any rapid compression that could occur when pressurizing a closed system. Scuba valves and regs are not designed for O2 service and contain flow paths that are not well suited to O2 use, and most scuba valves come up to pressure very fast. So always turn the valve on very slowly with the purge slightly depressed to ensure the system is not closed when initially pressurized.
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