Scubapro Mark 7 and Nitrox

[backinthewater]

I have been diving a Scubapro Mark 7 since 1980, and have never had a single problem with it. I have yet to go Nitrox because my LDS says I will have to replace it. Does anyone have any expertise on this? Can I not go Nitrox with the Mark 7? It is a big first stage, but it is certainly more than dependable.

Thanks

 

[DA Aquamaster]

If you have it O2 cleaned, have the o-rings replaced, and have it reassembled with christolube I don't see why it could not be used with nitrox.

Scubapro uses EDPM in it's current regulators but unfortunately older o-ring materials are still present in some of the annual service kits for older regulators. But this should not be a problem if the Nitrox is 40% or less.

But even with this limitation most of the o-rings in the Mk VII can be upgraded to the EDPM material. Scubapro tends to use standard sizes when possible and is evolutionary in its design approach.

For example the Mk VII uses the same piston shaft and piston head o-rings as the Mk V which just happens to use the same piston head and piston shaft o-rings as the newer MK 15, Mk 20, and Mk 25. The part numbers are the same, so new EDPM Mk 25 piston head and piston shaft o-rings can be used in the Mk VII. I am not in the mod to compare part numbers all night, but I would bet most of the other o-rings in the Mk VII also have a current EDPM version.

The LDS may just be overly cautious, but more likely they are just attempting to sell you a new reg.

 

[backinthewater]

DA Aquamaster
Thanks for the info. That pretty much verifies what I was thinking I would hear. I will pursue getting it cleaned. Thanks much for your help.

If you have it O2 cleaned, have the o-rings replaced, and have it reassembled with christolube I don't see why it could not be used with nitrox.

Scubapro uses EDPM in it's current regulators but unfortunately older o-ring materials are still present in some of the annual service kits for older regulators. But this should not be a problem if the Nitrox is 40% or less.

But even with this limitation most of the o-rings in the Mk VII can be upgraded to the EDPM material. Scubapro tends to use standard sizes when possible and is evolutionary in its design approach.

For example the Mk VII uses the same piston shaft and piston head o-rings as the Mk V which just happens to use the same piston head and piston shaft o-rings as the newer MK 15, Mk 20, and Mk 25. The part numbers are the same, so new EDPM Mk 25 piston head and piston shaft o-rings can be used in the Mk VII. I am not in the mod to compare part numbers all night, but I would bet most of the other o-rings in the Mk VII also have a current EDPM version.

The LDS may just be overly cautious, but more likely they are just attempting to sell you a new reg.

 

[scubatoys]

You shouldn't even have to get it cleaned. If you're just diving nitrox mixes of 40% or below, you don't need to do anything to a reg to dive in on those mixtures. Just hook up to a bottle and go!

Dan has done extensive studies on this very subject, and they have never found even 1 report of a problem with any material - rubber, titanium, brass, silicone, etc when the O2 mix is below 40... So if someone is telling you that you have to have work done to your reg to dive those mixes... they are either un-informed, or trying to take advantage of someone who doesn't know.

Now if you are going to be using it as a deco reg, with very high O2 mixtures, yes, then clean it - otherwise... just dive it.

 

[backinthewater]

Thanks guys, this pretty much verifies my suspicions - wanting to make a sale to me. Glad I brought it up, and thanks for the responses.

Happy diving

You shouldn't even have to get it cleaned. If you're just diving nitrox mixes of 40% or below, you don't need to do anything to a reg to dive in on those mixtures. Just hook up to a bottle and go!

Dan has done extensive studies on this very subject, and they have never found even 1 report of a problem with any material - rubber, titanium, brass, silicone, etc when the O2 mix is below 40... So if someone is telling you that you have to have work done to your reg to dive those mixes... they are either un-informed, or trying to take advantage of someone who doesn't know.

Now if you are going to be using it as a deco reg, with very high O2 mixtures, yes, then clean it - otherwise... just dive it.

 

[patymeboy]

how much did the mk 7 cost in the early seventies?
i payed $95 for my mk 5 then.
How much does it weigh?

 

[redacted]

I saw a picture of an Mk7 box on ebay with a proce sticker over $300.00. Hell of a price for a little noise!

Mine weighs about 2 lb.

 

[patymeboy]

i love this reg and have been collecting them compulsively

 

[redacted]

I only have one and dive it occasionally. If I am not wearing enough neoprene, it tends to screw up my trim. Few folks recognize it so it gets some interesting reactions. BTW, after studing the "honker" channel design, I was pretty sure that it would stop delivering gas to the primary 2nd at very low pressures. I confirmed in the pool that as the honking stops around 200 psi, the gas delivery is no longer sufficient to allow breathing. But the secondary will work normally so one diver can still breath OK. Just something that might be good for you and your buddy to plan on.