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Scubapro 108 (older model) exhaust valve

Mon Apr 30, 2018 10:06 pm

I had a few old scubapro 108s lying around and decided to get them back in service. Two were the newer models with the large purge/exhaust and the movable orifice. Two were the older ones with the fixed orifice and smaller purge/exhaust. The newer ones were easy enough to get going. I used the VDH replacement purge covers for the Scubapro 109s--they work fine. They also take the same main diaphragms as the 109.

The older ones had black rubber exhaust valves that were pretty stiff. The newer valves are 26mm diameter, and the older ones are 20mm. Both sizes are available in the VDH store. The main diaphragm in these older regs is recessed into the body, because the lever height is lower. Luckily, these were silicone and didn't need replacing. The 109 purge covers work ok--there is just a slight gap between the cover and the diaphragm. They purge fine, but you have to push 1/8 of an inch or so before the cover engages the diaphragm.

I ordered the 20mm valves, and they were indeed the correct diameter. Unfortunately, the stems and flanges were too narrow, with the flange slipping right through the hole in the spider. The distance from the diaphragm to the flange was also too long for the metal spider. I came up with a work-around I wanted to share:
I used a 003 HP spool o-ring on the stem, and it works perfectly! It works as a shim and the flange won't slip through. A small hemostat helps with placing the valve diaphragm and with putting on the o-ring. The old regs have a weird double spider that can make installation of the valve diaphragm difficult. Anyway, I finished up the overhaul, and they inhale pretty well. The exhale takes a little more effort than the newer regs because of the smaller exhaust opening. These older regs are not going to win any awards for work of breathing, especially at any depth, but this is a way to get them going again. The o-ring is quite secure, and I don't see any real risk of it being dislodged during normal use.
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Greg Barlow
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Re: Scubapro 108 (older model) exhaust valve

Tue May 01, 2018 9:01 pm

Thank you for sharing that solution.

Greg Barlow
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Re: Scubapro 108 (older model) exhaust valve

Sat May 05, 2018 12:09 pm

I include one with the early doorbell calypso/conshelf 2nd stage service kits. Simple solutions often work the best.

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Doing it right should include some common sense, not just blindly following specs and instructions. .Gary D, AWAP on SB

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Re: Scubapro 108 (older model) exhaust valve

Thu May 10, 2018 10:23 am

Ingenious workaround with the stem shim / spool o ring. I’m currently running a first gen Mk5 + 108 (older version) and just love it. I’m set to 1.6 in. H2o for cracking press. Dived the rig to 100 fsw this week in current to 60fsw and I thought the breathing was very impressive for the old girl. Not like the MR12 or the Conshelf XIV but still more than adequate. I really like it.

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