solution for D-series poppet seat DIY?

[Kupu]

When comparing the old D-series seats to an oring chart, I noticed the seat was close in size to the -105 oring. So I decided to order a few orings to test as seat replacements, going with 50 shore -104, -105, and 4mm X 8mm as possibilities.

When the orings arrived, the -104 appeared to have the best ID for the poppet stem and so gave it a try. I chose an AIR1 to play with, it is a little bit easier to reassemble and tune vs the D-series. For the first attempt, the small oring (approximately 1mm X 2.5mm) was left out, as I was not sure it had a purpose in this DIY configuration. The result was almost success, but I could not eliminate a very slight leak. I was out of time for the day, and set to project aside.

It occurred to me that the leak could be from a poor seal where the -104 oring meets the poppet shaft. When I returned to the project today, the leak seemed to be gone at first. I assume the oring had compressed and created a better seal after sitting for a few days, but dunking the AIR1 in water revealed a slight leak that could not be detected by my ears.

The 1mm X 2.5mm was then installed on the poppet stem, followed by the -104. Initial results are good, the leak is completely eliminated. The AIR1 has been pressurized for a few hours and cycled around 200 times. It breathes perfectly, as if it has original seat. Time to let it sit pressurized overnight and check again in the morning.

Has anyone else tried using orings for D seat substitutes?

 

[rsingler]

I have wrestled with this problem myself. See this thread:
For D-series lovers!
Interestingly, the original hardness of the patented seat was Shore A55!

The problem that I ran into is that air tends to leak along the shaft of the poppet stem despite the knife edge sealing well. So, you not only have to seal against the knife edge but also prevent air leakage at the center of the O ring. I could seal at 0.5" water column at a low IP without difficulty. I thought I was doing great! But when I tried for higher cracking efforts and higher IPs, the leaks would appear.

I believe that is why the factory seats are molded together with a metal disc, as a single item which presses rigidly against that tiny O ring at the top of the stem.

 

[lexvil]

My newest D350 came with a seat that I was able to flip over and so far it’s working fine.

 

[Kupu]

I have wrestled with this problem myself. See this thread:
For D-series lovers!

The problem that I ran into is that air tends to leak along the shaft of the poppet stem despite the knife edge sealing well. So, you not only have to seal against the knife edge but also prevent air leakage at the center of the O ring. I could seal at 0.5" water column at a low IP without difficulty. I thought I was doing great! But when I tried for higher cracking efforts and higher IPs, the leaks would appear.

I believe that is why the factory seats are molded together with a metal disc, as a single item which presses rigidly against that tiny O ring at the top of the stem.

Thanks for the information. My DIY seat setup was cracking at .5" and IP of 140, which is same as an AIR1 with normal seat I have been successfully diving. After reading your comment, I adjusted IP to 150 and cracking at 1.1" and there is still no leak.

I installed the tiny oring under the -104 oring rather than above, thinking it would seal the poppet shaft better in that position. Only time will tell if the hack holds up, but for the moment it works great.

Reading the thread you linked, it appears Timothy Moran had a solution but it was a bit of a process. The -104 oring takes all the work out of the process, press and play. And if I am understanding correctly, your punched seats work fine if appropriate IP and cracking pressure are used?

Apologies if I am being obtuse, but I am curious about your above comment of leak issue when trying for higher IP and cracking pressures in the context of DIY seats. I understand how higher IP can lead to leaks (then setting cracking pressure higher trying to compensate), and am thinking that is the correct way to read your comment. Or are you saying setting the cracking pressure higher could result in a leak independent of the IP?

My newest D350 came with a seat that I was able to flip over and so far it’s working fine.

Thanks to rsingler and ebay, I have a lifetime supply of D poppets and parts. I also picked up a few individual seats from VDH, but haven't found any flipable seats yet. A DIY seat solution would be the final key to keeping my D and AIR1 collection running for the rest of my days.

 

[Kupu]

I bought a 10 pack of the -104 orings, if anyone would be interested to try one out I will send a tester at no cost. Be aware that not all D poppets allow the seat to be replaced. (But you probably already know that if you are reading this thread).

 

[Kupu]

Keeping the AIR1 submerged in water to verify no leaks, went up to 170 IP and no bubbles.

 

[lexvil]

I would love to try the oring. I had t given it much thought before but I did notice if I had a marginal seat with a very small dribble, many times turning the spring in (tighter) with result in a much bigger leak, I’ve yet to even ponder the why of it.

 

[rsingler]

I'm very impressed!
What material did you use for 50 shore?
Nice work!

 

[Kupu]

I'm very impressed!
What material did you use for 50 shore?
Nice work!

This is the silicone oring used. My original thought was to attempt using heat and weight to flatten and reshape the orings, and perhaps apply a sealant where the oring meets the shaft. But all that may not be necessary, I took the oring out of the bag, installed it on the poppet, & done.

I left the regulator pressurized overnight at 160 IP but first stage shut off. Everything stayed locked up with zero leakage, still at 160 this morning. Looks good.

 

[lexvil]

So cool if this is the answer to the seat issue, and the thin poppet base o-ring and the majority of the moving parts are covered, now for diaphragms...