Long...MK10 plus ?

[NotSure]

I believe rhwestfall has it right, must be a polyurethane O-ring for a DIN connector. I don't know what I was thinking the MK10 wouldn't need the crush washer because it uses the MK20 seat.

 

[NotSure]

the "bushing" is a wiper, and should go on above the plastic hood on the piston, riding on the piston shaft inside the spring. Again, IIRC, something for "icing"...

I always assumed that it was for harmonic dampening as it has no other apparent purpose. I can see how it might be for thermal insulation.

 

[rhwestfall]

Wasn't the original idea behind the 10+ for higher pressures (4k)? But then the thermal things (SPEC included as you will see most 10+ being SPEC) were "enhancements" for cold tolerance, including the "cap" on the piston?

 

[NotSure]

Wasn't the original idea behind the 10+ for higher pressures (4k)? But then the thermal things (SPEC included as you will see most 10+ being SPEC) were "enhancements" for cold tolerance, including the "cap" on the piston?

It seems pretty obvious that the extra plastic bits are for cold tolerance but was it done to make it more cold tolerant than the MK10 or just to offset the added cooling due to higher flow rate of the dull edge piston. If someone has the marketing info on the 10 plus it would be interesting to see what the selling points were. The only MK10 PLUS I ever got came with the centering washer broken so I converted it to MK10 and sold extra bits.

 

[buddhasummer]

Does anyone have a spare or two of the spring centering washer 10-500-118? Cheers

Scrap that, got a couple.

 

[buddhasummer]

Just for anyone who's interested, it appears all MK10 Plus parts are still currently available save SPEC boot, still looking into seat retainer, will post back once I get an answer.

 

[buddhasummer]

I use plain old camera O ring silicone grease when servicing my regs, I only dive 21%, should I be using Christolube or similar? Cheers.

 

[halocline]

I think the advantage for the MK10+ was increased air flow. I don't think it had anything to do with higher tank pressures; it should be identical to the MK10 in that regard. I don't think there's any cold water advantage either, in fact if anything it would be more freeze-prone than the MK10 due to higher flow rates. I suspect SP was developing seats and pistons specifically to increase air flow and this was part of that development.

The centering washer was supposedly deemed necessary to prevent IP creep. Because the piston is not a knife edge and does not cut a groove in the seat, I guess they found that any mis-alignment of the piston could result in problems in sealing. Who knows. The MK10+ was notorious for IP creep, although the current MK20/25 seat might help with stable lock up.

I've always been curious about the MK10+ and tried to find a conversion kit at one time or another, but I doubt I would convert all my MK10s even if I had the kits. Once you do that you are tied to the MK20/25 seat which is long lasting, but expensive and hard to find on its own. I have a good supply of MK5/10 seats, probably enough for the next 15-20 years.

Edit: Another advantage of the MK10+ that I can think of is the ability to adjust IP without disassembling the regulator. Simply remove the seat retainer and add/subtract washers.

 

[rhwestfall]

read it as you wish, perhaps it is a result rather than a cause...

 

[rhwestfall]

1. The flat edge on the piston stem prevents the prior utilized knife edge from cutting right through the seat, allowing use with higher pressures.

2. The reduction in turbulence associated with the rounded edge provides for more flow.