Light yoke vs. heavy yoke.

[raftingtigger]

I'm returning to active diving after a pause of a few years. This isn't my first pause in diving over the last 39 years, and I have never had a problem with either skills or comfort when resuming.

However, it does bring up an important issue. Last time I was diving most tanks (at least rentals) were filled to 2200 psi not the 3200 psi in the tank I rented yesterday. My personal regulator is a first generation Scubapro Mark 7 (bought new in 1971) and I have loved it. I have a small air leak from the ambient pressure ports (one or both of the hp piston o-rings is leaking) and was planning on replacing them. In researching the o-ring sizes (my tech manual, also from 1971, lists outdated part numbers) a light yoke was mentioned. Since I have a first generation model I'm sure mine is a light yoke. Is that safe to dive with a 3000 psi fill? If not (most likely) then I have 2 options. First, bleed off pressure until my fill is only 2200 psi - since I only use at most 1/2 tank for my buddy's full one (any one I have dove with) that shouldn't decrease my effective dive time. Second, I can get another 1st stage to replace my Mark 7.

Any thoughts?

 

[Fishpie]

......or use LP tanks.

 

[Fishpie]

More helpfully though, you can pick up a Scubapro MK10 1st stage for about $50 on eBay.....has more ports and better hose routing. A later MK5 would also work.

Old(er) LP 72's would be about the same price.

 

[redacted]

Or you can watch for a heavy yoke Mk7 on ebay. They show up fairly regularly and are my favorite 1st stage. Scubapro recommends a limit of 2475 on that older Mk7. Some divers on this board use that yoke with 3000 psi tanks and report no problem. If it is not strong enough, you can probably expect any failure to be difficulty getting the reg to seal and a slow leak - not a catastrophic failure.

 

[Couv]

I'll try to attach a file to this post. The o-ring sizes are annotated on it, but note that the piston stem o-ring- Item 25 should be a duro 90.

 

[Couv]

....and here is one from the Master. (Awap)