Workhorse Pony Reg: MK5, MK10, MK10 SPEC?

[HenrikBP]

I'm shopping for a first stage for a pony bottle. I don't dive really cold water, but will begin diving off the NE Coast next year.

I'll be using a G250 second stage and was thinking an MK5 or MK10 first stage would be a good and less expensive match. Thoughts? Pros/cons to either?

If I go with MK10 would it be worth it to try to find one with the grove for the SPEC seal for environmental sealing?

Thanks
Henrik

 

[halocline]

I'm sure any of those would be work fine, and a MK2 would be another good choice. If you are not using an SPG on the pony, the MK2 will give you an indication of a nearly empty tank, although using the G250 would tend to counteract the increase in breathing resistance with the drop in IP at low tank pressure from the unbalanced MK2. BTW, if you can find a SPEC boot for the MK10, please let me know where you found it!

 

[DA Aquamaster]

The Mk 10 G250 is a great pony reg.

The later Mk 10's had a groove for a SPEC boot, while the early ones just relied on very small holes to retain the silicone. I have 3 or 4 of each MK 10 I'd be willing to sell - and I do have a couple SPEC boots for the older style Mk 10's.

SP moved away from silicone to make the reg more compatible with Christolube and nitrox use at the time given the O2 clean conventions in use then. But perhaps more importantly they eliminated the use of silicone to avoid cross contamination on the bench, tools, etc, when servicing O2 clean regs.

You can still use silicone in the ambient chamber but not many SP techs will still do that for you - it is very messy and is no longer SP approved. You could also pack the chamber with Christolube, (the approach Atomic took) but it is more expensive and again it is not an Sp approved method so many techs won't help you with that for liability reasons.

Personally, for water below 40-45 degrees, a SPEC equipped Mk 10 would be hard to beat as a pony reg.

Larry

 

[HenrikBP]

Thanks for the great info.

Henrik

 

[redacted]

Personally, for water below 40-45 degrees, a SPEC equipped Mk 10 would be hard to beat as a pony reg.

Larry

Would the flow-by design of the Mk2 produce less cooling of the piston head and the exposed upper shaft, thereby producing less tendency to form ice? How does the Mk2 perform in cold water?

 

[DA Aquamaster]

Makes sense to me. The Mk 2 is great in cold water and I know several ice divers who use them.

Larry

 

[Packhorse]

The only problems I see with the MK5 are
Hard to get Din fitting
odd sized HP port.

 

[Couv]

Makes sense to me. The Mk 2 is great in cold water and I know several ice divers who use them.

Larry

I'm now a www, just curious, is that without the enviro kit?

c

 

[HenrikBP]

The only problems I see with the MK5 are
Hard to get Din fitting - odd sized HP port.

I knew about the DIN fittings, but not about the HP ports. Thanks. I have been searching around for the differences between MK5 and MK10 and this helps.

Henrik

 

[redacted]

I knew about the DIN fittings, but not about the HP ports. Thanks. I have been searching around for the differences between MK5 and MK10 and this helps.

Henrik

Depends on the vintage of the Mk5. Older Mk5s had one HP port and I believe that was sized the same as the LP ports. Newer Mk5s have two HP ports and I believe they are the current modern size for that connection. But I am not sure the change goes together in all cases.