Using M50 diaphragm and 11.250.141 lever in a 109 case

[elan]

Hi everyone,

I had some leftover 109 with many parts missing - a diaphragm, purge cover, adjustment knob, lever and the orifice also had a bunch of nicks on it. The case was in a good shape however.

I finally decided to dig through my parts box and try to make something working out of it. I dug out some S wing poppet which was left from another reg - I think one of the older 250 ies with a balance chamber and a spring. I had a VDH reproduction purge cover and I also found the adjustment knob from a G250 - the one with a plastic knob molded over metal shaft. But the other things were missing.

I found a broken M50 which had some plastic bits cracked in the case so it was garbage. But it still had some parts usable. Plastic orifice was in a great shape no visible nicks under 10x magnification even and my nail ran over the edge smoothly.

The lever and the diaphragm were in a great shape - the diaphragm was a bit dirty but after washing it well it looked brand knew. Stretching it did not uncover any holes or irregularities either.

After assembly the reg works well, just like any other 250v and BAs I have. My worry is whether I might get any issues with the diaphragm down the road because it does look slightly different more dome shape than those on BAs. It does properly fit however and I was able to tune it easily just like other BA/250.
The lever seems to be the same as used on G250Vs per SP schematics (2010) so I think it should not be an issue.

What do you think, should I look for a 250 diaphragm or just dive it as is. I will take it for a test dive sometimes next week.

Thanks in advance,.

 

[elan]

Here is a pic of my frankenstein 109

 

[Julius SCHMIDT]

Great. What's an M50

 

[Jcp2]

Scubapro M50...Any good?

I am curious about this second stage as I have seen a few lately floating around. So far I have been able to find out that it was paired with the MK20 first stage and seems to be a primary and not an octo. It also uses the same parts kit as the G200, which is still supported by Scubapro...

scubaboard.com

Seek and ye shall find.

 

[lexvil]

Hi everyone,

I had some leftover 109 with many parts missing - a diaphragm, purge cover, adjustment knob, lever and the orifice also had a bunch of nicks on it. The case was in a good shape however.

I finally decided to dig through my parts box and try to make something working out of it. I dug out some S wing poppet which was left from another reg - I think one of the older 250 ies with a balance chamber and a spring. I had a VDH reproduction purge cover and I also found the adjustment knob from a G250 - the one with a plastic knob molded over metal shaft. But the other things were missing.

I found a broken M50 which had some plastic bits cracked in the case so it was garbage. But it still had some parts usable. Plastic orifice was in a great shape no visible nicks under 10x magnification even and my nail ran over the edge smoothly.

The lever and the diaphragm were in a great shape - the diaphragm was a bit dirty but after washing it well it looked brand knew. Stretching it did not uncover any holes or irregularities either.

After assembly the reg works well, just like any other 250v and BAs I have. My worry is whether I might get any issues with the diaphragm down the road because it does look slightly different more dome shape than those on BAs. It does properly fit however and I was able to tune it easily just like other BA/250.
The lever seems to be the same as used on G250Vs per SP schematics (2010) so I think it should not be an issue.

What do you think, should I look for a 250 diaphragm or just dive it as is. I will take it for a test dive sometimes next week.

Thanks in advance,.

I would dive it, probably with a shut off valve in line just as a precaution but I doubt those parts will have any issues.

 

[elan]

I would dive it, probably with a shut off valve in line just as a precaution but I doubt those parts will have any issues.

Yeah thats what I’m thinking. Its a reg on my doubles so I can shut it down in case of an issue.

 

[rsingler]

I think you're going to be just fine! The extra height of the M50 diaphragm will probably get collapsed by the back of the rubber cover, and the tiny feet on the 11.250.141 lever will make no difference inside the barrel of the 109. The slightly increased foot size may help increase poppet opening, and that's a good thing.
You can assess this with a lever height check. With the barrel assembly complete, lay the diaphragm on the case and assess the distance between the back of the diaphragm and the lever with a gentle "tap tap" on the center disc. Now do the same thing with a thin dowel through the central hole in the rubber cover with it pressed in place. If the "tap tap" distance seems to lessen, then the rubber cover is probably pushing on those big rubber dots or the center disc and squashing the height to approximate a 109 diaphragm. Once you're under water, hydrostatic pressure will balloon in the floppy sides of the diaphragm and it will act normally.
If, in contrast, the tap tap distance disappears completely when you press the rubber cover (and faceplate) into place, then the diaphragm disc may be starting to press on the lever already. It it doesn't freeflow, it's about to, and you may find the reg less stable under water. As I recollect, the M50 diaphragm is less than 1mm thicker at that center point than a 109/250 diaphragm, so I doubt this will be a problem. And recall that the lever drops a millimeter or so when the reg is pressurized, so check this under pressure as well.
But if normal lever height can't be maintained without screwing in the orifice to maintain a seal (indicated by a higher than desired cracking effort), you may not have enough lever excursion for safe diving at depth.

 

[elan]

I think you're going to be just fine! The extra height of the M50 diaphragm will probably get collapsed by the back of the rubber cover, and the tiny feet on the 11.250.141 lever will make no difference inside the barrel of the 109. The slightly increased foot size may help increase poppet opening, and that's a good thing.
You can assess this with a lever height check. With the barrel assembly complete, lay the diaphragm on the case and assess the distance between the back of the diaphragm and the lever with a gentle "tap tap" on the center disc. Now do the same thing with a thin dowel through the central hole in the rubber cover with it pressed in place. If the "tap tap" distance seems to lessen, then the rubber cover is probably pushing on those big rubber dots or the center disc and squashing the height to approximate a 109 diaphragm. Once you're under water, hydrostatic pressure will balloon in the floppy sides of the diaphragm and it will act normally.
In, in contrast, the tap tap distance disappears completely when you press the rubber cover (and faceplate) into place, then the diaphragm disc may be starting to press on the lever already. It it doesn't freeflow, it's about to, and you may find the reg less stable under water. As I recollect, the M50 diaphragm is less than 1mm thicker at that center point than a 109/250 diaphragm, so I doubt this will be a problem. And recall that the lever drops a millimeter or so when the reg is pressurized, so check this under pressure as well.
But if normal lever height can't be maintained without screwing in the orifice to maintain a seal (indicated by a higher than desired cracking effort), you may not have enough lever excursion for safe diving at depth.

Thank you, Sir, for such a detailed answer. I will check the cranking effort tomorrow, finished late last night and did not have time to measurе. I did not notice anything abnormal with the lever height yesterday but your tap tap method will provide more instrumental measurement.