Can someone please identify this 1st stage

[buddhasummer]

Thanks for sharing. Yeah, I've become more interested in robust, reliable and easy to service regs of late and I guess nothing says robust like a metal second stage. A metal reg is going to be my choice if I ever get to do my dream year long diving safari. I'll dive both the SP and Conshelfs over the next twelve months and decide which one I prefer. I think the Conshelf wins on simplicity and probably robustness. Breathing wise at this stage I'm unsure.

 

[buddhasummer]

I do think the SP is prettier though.

 

[halocline]

I have been mostly using MK-10's for the last 20 years, but was reading that the MK-15 could handle higher tank pressures more easily.


There is not a lot of chrome left on the 109 and the adjustment knob which is all brass is pretty bent, but it works.

I sometimes have trouble with the exhaust valve leaking a little and the case itself (somewhere) leaks a tiny bit when I suck a vacuum on it.

It's definitely true that the MK15 has more stable IP at higher pressures; there's tighter tolerance around the HP o-ring due to the bushings, and the larger piston head probably helps a bit too. I think the MK15 is an under-rated 1st stage, as long as it has had the adjustable seat retainer replaced. It's easy to see; if there's a hex fitting on the HP side of the regulator, it's the original seat retainer, and if it has 2 small holes for a pin spanner (like the MK10) then it's been replaced. SP had a spectacular problem with those original adjusting seat retainers. Techs were adjusting the IP by screwing in/out the retainer while the reg was under pressure, which allowed the piston knife edge to basically saw it's way into the seat. Occasionally the piston would get stuck in the seat (immediately cutting off all air) or just cut seat into pieces. (immediately allowing all HP air to pass)

So there was a recall and the updated seat retainer did away with the nutty 'rotate the seat to adjust IP' idea and returned to the stationary seat retainer and shims for adjusting IP. My MK15 is super reliable and going on 6-7 years since I rebuilt it. It still locks up perfectly but I don't use it too much. There are a couple of oddball things about working on them; they need a specific set of circlip pliers and a specific bushing tool. Plus the seat is unique and not as easily available. But the performance is for all practical purposes similar to the MK20/25, and usually at a much lower price.

Your exhaust valve leak might be from a dent or slight corrosion around the "spider" where the exhaust valve seals. I've had that happen on some of my 109s. The exhaust valve, mouthpiece, or diaphragm are about the only places you could have a vacuum leak in those regs. The diaphragm would be pretty obvious, I would think. I've never had a torn one.

 

[PfcAJ]

As per title, from the photo I'm unsure. Thank you.

View attachment 386393

Thats purdy

 

[dumpsterDiver]

It's definitely true that the MK15 has more stable IP at higher pressures; there's tighter tolerance around the HP o-ring due to the bushings, and the larger piston head probably helps a bit too. I think the MK15 is an under-rated 1st stage, as long as it has had the adjustable seat retainer replaced. It's easy to see; if there's a hex fitting on the HP side of the regulator, it's the original seat retainer, and if it has 2 small holes for a pin spanner (like the MK10) then it's been replaced. SP had a spectacular problem with those original adjusting seat retainers. Techs were adjusting the IP by screwing in/out the retainer while the reg was under pressure, which allowed the piston knife edge to basically saw it's way into the seat. Occasionally the piston would get stuck in the seat (immediately cutting off all air) or just cut seat into pieces. (immediately allowing all HP air to pass)

So there was a recall and the updated seat retainer did away with the nutty 'rotate the seat to adjust IP' idea and returned to the stationary seat retainer and shims for adjusting IP. My MK15 is super reliable and going on 6-7 years since I rebuilt it. It still locks up perfectly but I don't use it too much. There are a couple of oddball things about working on them; they need a specific set of circlip pliers and a specific bushing tool. Plus the seat is unique and not as easily available. But the performance is for all practical purposes similar to the MK20/25, and usually at a much lower price.

Your exhaust valve leak might be from a dent or slight corrosion around the "spider" where the exhaust valve seals. I've had that happen on some of my 109s. The exhaust valve, mouthpiece, or diaphragm are about the only places you could have a vacuum leak in those regs. The diaphragm would be pretty obvious, I would think. I've never had a torn one.

Thanks, yeah the end has spanner holes and the tech who fixed it is somebody i trust. As for leaks.. it's weird, i did have to polish the case which has no chrome left under the exhaust valve. I know the diaphram has no holes..

I have several 109's and i just keep using the oldest one for some reason, I have much better looking ones with more chrome.. maybe my grandchildren will use them in 20 years.

 

[HeatCker]

i've got a 108, it leaks a little, breathes a little moist
couldn't really figure out where it leaked when i dry sucked on it as the leak is so small
after reading this thread i checked the case and scrubbed under the exhaust valve
then i rinsed both inside and out
while it was wet/moist i vacuum tested it again
this time because of the moisture i could clearly hear the exhaust valve is not sealing 100%
not enough to worry but now i know
thanks dumpster / halocline

 

[buddhasummer]

I got it for $176 shipped.

 

[halocline]

You got a good deal if it's in as good shape inside as it looks to be. I bet it is. I believe that this particular balanced/adjustable is a very late model with some matte parts. I guess it could have been sold new with the MK15. I also suspect that SP was selling G250s at the same time.

When you get it, send me a photo of the MK15 from the HP side. If it's NOS, it probably has the old style seat retainer I was talking about in an earlier post. If so, I would not use it as is. I think I have an update kit to replace the seat retainer.

 

[buddhasummer]

Thanks Matt, will do.

 

[NotSure]

It will be interesting to see what version of the balanced poppet comes out of one the last 156's made. I would think maybe the rivet style or maybe even the s-wing with one o-ring. I wonder if they printed up some of the old 109 covers till they ran out and went to all satin chrome?