New data/info for my regulator.

Ok, this concerns the spring-washers.

Firstly I decided a firing pressure of 2000psi was adequate for each shot, from a volume of approx 19 cubic CM. If that is in the ball-park…

The compressed air has to flow from the main bottle into the regulator chamber. When the pressure in the regulator chamber reaches 2000psi the flow from the main bottle needs to be shut off. I devised a design where this was to be done by the pressure in the reg-chamber acting upon a piston in a shaft that would force a block across the inflow from the main bottle.

The main consideration in this was a spring that would fully compress and shut the gate at 2000psi. All of this needs to fit in a tube no greater than 16mm diameter (the space in the neck of the bottle).

Given that, the valve inside the reg-chamber needs to be no bigger than 10mm diameter.

A coil-spring of that OD would need to be approx 18″ long to compress and give sufficient travel to a shut-off pin at 2000psi. Not viable at all.

So, spring-washers.

One spring-washer at 10mm OD x 5mm ID x 0.5mm thick requires a force of 325N to deflect 75% (the max recommended deflection for this washer). 2000psi is 1100N. Three washers = 975N, a bit too low, so have to go up one to x4 washers = 1300N (a bit more than 2000psi, but close enough).

To get the neccesary travel, at least 2mm at 75% deflection, 56 washers are required, mounted in 14 series of 4 (alternate facing). This causes all the washers to deflect at only the force needed for four.

Still with me? 😯 😆

Free space required for 56 washers: 31.5mm
At 15% pre-load (required): 30.94mm
At 75% deflection (recommended max): 28.84mm

Add 3mm for the piston and that’s a total valve-area length of approx 35mm inside a reg-chamber tube measuring approx 25cm in length (at 16mm OD).

If the volume lost to the valve area (approx 0.75cm radius x 3.5cm length = approx 6 cubic cm) is deducted from the total reg-chamber area (0.75 radius cm x 25cm length = approx 19 cubic cm) it’ll leave approx 13 cubic cm at 2000+psi. Enough for a good shot?

Anyway, that’s where I’m at right now. Comments welcomed as always. 🙂