Mk2 or mk10 for deco bottle

Which first for deco bottle

  • MK2

    Votes: 5 71.4%
  • MK10

    Votes: 2 28.6%

  • Total voters
    7
  • Poll closed .

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I’m taking deco procedures next month and I’m trying to decide which first stage to run with my g250 for my deco bottle. We will be using 50% and aluminum 40 bottom mounted. I have a mk2 and a mk10 available.
https://scubaboard.com/community/attachments/deco1-png.819668/
https://scubaboard.com/community/attachments/deco2-png.819669/

I use DIN MK2 for Deco on AL80s and AL40s. No hose routing problems.
They used to be yokes but I changed them over a few years ago, when many dive shops started carrying DIN tanks.

It is possible to unscrew the DIN Post from the first stage under pressure by rotating the body.
Unscrewing DIN regulator from tank valve

Edit to add:
But don't take advice from idiots on the internet. Most of this forum has me muted.
 
I use a MK2 for high FO2 bottles because theoretically it is easier to get and keep O2 clean. In the real world I’m not sure it matters. But the MK2 has a great design for O2 use; there are only three static o-rings (two in the DIN retainer and the HP port) and a tiny seat, with an O2 compatible version available, exposed to HP gas.

I use MK5s (or 10s) for stages but in the diving I do those are always 32% or lower. They work great. I love them, I know how to work on them, and I have found them to be every bit as reliable as the MK2. So I think you’d be perfectly fine with either.

There is one thing, though, about O2 cleaning old regs; it’s very difficult IME to get every trace of old silicone grease out of them, especially if it’s been lathered on. It’s easy to get most of it out, but I have spent hours soaking, rinsing in boiling water, lots of agressive brushing, etc. It’s hard to imagine someone at a shop putting in the time that I have to make sure that the final rinse water is spotless. Does it matter….who knows, we all have our obsessions I guess.
 
I use a MK2 for high FO2 bottles because theoretically it is easier to get and keep O2 clean. In the real world I’m not sure it matters. But the MK2 has a great design for O2 use; there are only three static o-rings (two in the DIN retainer and the HP port) and a tiny seat, with an O2 compatible version available, exposed to HP gas.

I use MK5s (or 10s) for stages but in the diving I do those are always 32% or lower. They work great. I love them, I know how to work on them, and I have found them to be every bit as reliable as the MK2. So I think you’d be perfectly fine with either.

There is one thing, though, about O2 cleaning old regs; it’s very difficult IME to get every trace of old silicone grease out of them, especially if it’s been lathered on. It’s easy to get most of it out, but I have spent hours soaking, rinsing in boiling water, lots of agressive brushing, etc. It’s hard to imagine someone at a shop putting in the time that I have to make sure that the final rinse water is spotless. Does it matter….who knows, we all have our obsessions I guess.
Super dumb question here:
Do you use an ultrasonic cleaner or any kind of solvent to get rid of the silicone grease or O2 grease?
 
I have a couple mk2s I used for deco, worked great for high PO2 mixes.

One work of caution with them though: There is an o-ring at the base of the piston on other SP regs, that is NOT on the Mk2. If the technician isn't paying attention or is not used to doing mk2, they'll put that o-ring on the piston anyway. Most of the time, it'll be fine, but it can cause the HP orifice to be blocked, and you won't get accurate pressure readings on the SPG. I saw two that were reading 1500ish PSI with the regulator OFF the tank. Whoever serviced them wasn't using SP parts either, so it was a bit of a hack job, but something to be aware of.
 
Super dumb question here:
Do you use an ultrasonic cleaner or any kind of solvent to get rid of the silicone grease or O2 grease?
Sure but the ultrasonic is better for acidic cleaning. I use simple green and dawn dish soap for de-greasing. Silicone stands up to a lot of solvents, that’s one of the things that makes it a good lubricant.

What I do is after the scrubbing and rinsing, I’ll pour some boiling water into a very clean bowl or pan, then soak the regulator parts in it, I just let it sit for a few hours. Then I check the surface of the water for trades of silicone or anything else. I might have to go through this a few times when O2 cleaning a 1st stage for the first time that’s had some silicone used. Subsequent cleanings are a lot less time.
 
I have a couple mk2s I used for deco, worked great for high PO2 mixes.

One work of caution with them though: There is an o-ring at the base of the piston on other SP regs, that is NOT on the Mk2. If the technician isn't paying attention or is not used to doing mk2, they'll put that o-ring on the piston anyway. Most of the time, it'll be fine, but it can cause the HP orifice to be blocked, and you won't get accurate pressure readings on the SPG. I saw two that were reading 1500ish PSI with the regulator OFF the tank. Whoever serviced them wasn't using SP parts either, so it was a bit of a hack job, but something to be aware of.
I have no idea what you’re talking about and I am very familiar with both the MK2 and the SP balanced piston regs. Somebody is telling you stories. If a technician is not capable of accurately rebuilding a MK2, that individual needs a different line of work.
 
One work of caution with them though: There is an o-ring at the base of the piston on other SP regs, that is NOT on the Mk2. If the technician isn't paying attention or is not used to doing mk2, they'll put that o-ring on the piston anyway. Most of the time, it'll be fine, but it can cause the HP orifice to be blocked, and you won't get accurate pressure readings on the SPG. I saw two that were reading 1500ish PSI with the regulator OFF the tank. Whoever serviced them wasn't using SP parts either, so it was a bit of a hack job, but something to be aware of.
I can't figure out what you are describing...
1731610727871.png
1731610663864.png
 
I can't figure out what you are describing...
I had to go back to my manuals to figure out what I was talking about too... it's been a few years. It must have been an incorrect o-ring that was put at the tip of the piston (22 in the mk2 diagram). I was thinking it was part 41 below, but that wouldn't block the HP port.

Screenshot 2024-11-14 at 1.11.17 PM.png


But as I said, it was a hack job in the first place.
 
https://www.shearwater.com/products/teric/
http://cavediveflorida.com/Rum_House.htm

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