MK19 EVO/ G260 Parts, rebuild

[Divemorestressless]

Has anyone been using the mk19 evo with trimix? I have emailed SP to get it from the horses mouth.

I came across a post somewhere that says that Scubapro said mk17 not recommended for helium use, as it permeates the diaphragm and cracks plastic.

 

[rhwestfall]

Hey, look at that, your post count is high enough to message folks. I'd ask @rsingler that question if you reach out to him...

 

[RyanT]

Scuba Gaskets is a good source for kits. I'd be astounded if helium cracked plastic. It's an inert gas.

 

[Nemrod]

Has anyone been using the mk19 evo with trimix? I have emailed SP to get it from the horses mouth.

I came across a post somewhere that says that Scubapro said mk17 not recommended for helium use, as it permeates the diaphragm and cracks plastic.

I have not heard that and it would certainly be included in the product description being as trimix is not terribly unusual these days for tech divers who often use Scubapro regulators.

There is nothing particularly different about a Mark 11/17/19 diaphragm that would make it more susceptible to hydrogen infusion than any other diaphragm type regulator. Better just get a piston reg then to be sure .

 

[rsingler]

The Mk19EVO is a great regulator for technical use (with Helium). Actually, even pistons are great technical regs (wink, wink). The potential issue with diaphragm regs is that since Helium is such a small molecule, it diffuses through the diaphragm if left pressurized for long periods. Then it accumulates under the environmental seal, causing it to bulge and causing the regulator to lose a few feet of depth compensation until the bubble is compressed by ambient pressure. No big deal. Take off the seal, smooth it out, and put the cap back on.

 

[Divemorestressless]

×The Mk19EVO is a great regulator for technical use (with Helium). Actually, even pistons are great technical regs (wink, wink). The potential issue with diaphragm regs is that since Helium is such a small molecule, it diffuses through the diaphragm if left pressurized for long periods. Then it accumulates under the environmental seal, causing it to bulge and causing the regulator to lose a few feet of depth compensation until the bubble is compressed by ambient pressure. No big deal. Take off the seal, smooth it out, and put the cap back on.

Thanks for the great reply.

The only experience I had with mk25 was around 2000. I jad issues with scoring and gave up on pistons.

I occasionally sidemount in caves. That's why I leaned toward a diaphragm. Are the modern pistons okay for this type of diving?

 

[rhwestfall]

There are a bunch of good diaphragm firsts out there....

 

[rsingler]

The only experience I had with mk25 was around 2000. I had issues with scoring and gave up on pistons.

I occasionally sidemount in caves. That's why I leaned toward a diaphragm. Are the modern pistons okay for this type of diving?

I'd reply, but I don't want @BoltSnap to get mad at me.

 

[Divemorestressless]

There are a bunch of good diaphragm firsts out there....

I was deciding between apeks xtx50 and sp mk19evo g260. Not too late to make a swap, wanted easiest breathing and reliability with a turret, and sealed diaphragm.

 

[Nemrod]

I was deciding between apeks xtx50 and sp mk19evo g260. Not too late to make a swap, wanted easiest breathing and reliability with a turret, and sealed diaphragm.

Hydrogen slowly diffusing through a diaphragm in a Scubapro 11/17/19 is also going to diffuse through any other similar diaphragm regulator. In a Mark 11 it would not accumulate as it is not enviro sealed and neither would a piston regulator (even if pretending to be sealed) whereas the 17/19 are sealed so the helium might accumulate within the ambient chamber. Any helium that accumulates in the ambient chamber is going to find it's way out of there also. I cannot see helium diffusion to be a problem.

There is always the unique Sherwood piston first stages, sealed and vented.

(Edit to add, I am not trimix certified)