HW seat update.
I finally got a chance to dig around, find some stuff and do some testing. I found a HW single hose reg that uses the same HP seats, both hard and soft that the DH regs use. It is much easier to tinker with and allows me to check and adjust IP as opposed to a DH which will not allow me to do any monitoring of the IP.
First off, does anyone have any experience with the HW single hose regs that use this seat? What I am interested in is how they "normally" perform, I would hate to be chasing a huge increase in performance over what is normal, at least at first. More on this later.
I checked the HP seat that was in the reg, it would not hold IP, then I replaced the seat with a NOS seat I had, it was a little better but not much. I found the hard seat was not well machined and had a lot of machining grooves in it. This was part of the unstable IP, I polished the seat to remove the grooves which helped, the NOS one I have has the same grooves so I suspect these seats were never close to performing the way we expect of a modern reg to seal. Next the IP was not real stable, it jumped around a lot and was difficult to set with the adjustment screw. I suspected the diaphragm had gotten hard and was contributing to the problems. I took it apart and replaced the rubber with a USD diaphragm. The replacement is easy and it helped stabilize the IP a good bit.
With that done, I moved to making a replacement seat. I had a piece of 1/2 nylon rod that I used. The angle on the seat face turned out to be 45 deg which is pretty easy to duplicate. I turned the stock down to the correct diameter to fit in the reg, cut the 45 angle on the end, drilled a small hole and inserted a short piece of SS pin. The piece was cut off, turned around in the lathe, and bored for the spring. To increase the flow area around the seat, I sanded flats on 4 sides, basically the same way a Mistral seat is made.
With the seat made, I moved to testing it. It seems to work a good bit better than the NOS OEM ones but it still does not lock up well. With the IP set to 120 and tank pressure around 2500, it locks up but creeps up another 15 psi over a minute of so then appears to stop. This is at higher tank pressures. At around 500 psi I can not get it to stabilize, the IP locks up but then continues to creep up until the second stage opens. I am wondering if this is "normal" for this type of seat. While not ideal and no where close to acceptable by modern standards, it would work OK. Going back to my earlier question, does anyone have any experience with these regs from back in the day? Is it "normal" for the IP to be unstable at low tank pressures?
Bottom line on what I have so far. It is fairly easy to reproduce these type seats but I need a better understanding of how well they can be expected to work. A slightly different material that is a bit softer may work better. The material I am using appears to be roughly the same hardness as the OEM seats.
I am not/will not be making them for use, this is just an exercise in "can I make them" for my own interest but thought some of you might be interested in what I have found out.