# Before I go asking more AC questions

Joined: March 1st, 2002, 12:22 am

gonna spend a couple days searching and reading up..... at least try to get a good back ground going.

dr_subsonic's pneumatic research lab

the Lunatic Fringe of American Airgunning
Southwest Montana's headquarters for Airgunning Supremacy

Joined: April 28th, 2010, 12:23 am
good , ive been researching foster connection checkvalve systems for days , although the info is severly limited thus far...They are really simple , i just cannot see why they are not sprung shut

Joined: August 5th, 2006, 11:55 pm
On a Foster fitting with the sealing rod, think of the air pressure in the air cylinder as the return spring.

So, you have pumped 1000 psi into the rifle's air cylinder. When you exhaust the pressure at the Foster connection, the air inside the air cylinder tries to rush out to atmosphere. The rushing air applies force to the area of the check valve and moves it forward. Once the sealing surfaces mate, you have the full force of the trapped air pressing on the area of the sealing surface.

So, on an M-rod, you have about 1/4 inch OD since the guide pin is facing towards atmosphere.

This takes you to the formula of, F = (pi * Rsquared) * cylinder pressure, which leads you to the amount of force applied to the face of the check valve.

Pretty good return spring.

Have Fun!

Chris

Joined: September 23rd, 2002, 6:16 pm
good , ive been researching foster connection checkvalve systems for days , although the info is severly limited thus far...They are really simple , i just cannot see why they are not sprung shut
best system IMO.

Joined: September 23rd, 2002, 6:16 pm
On a Foster fitting with the sealing rod, think of the air pressure in the air cylinder as the return spring.

So, you have pumped 1000 psi into the rifle's air cylinder. When you exhaust the pressure at the Foster connection, the air inside the air cylinder tries to rush out to atmosphere. The rushing air applies force to the area of the check valve and moves it forward. Once the sealing surfaces mate, you have the full force of the trapped air pressing on the area of the sealing surface.

So, on an M-rod, you have about 1/4 inch OD since the guide pin is facing towards atmosphere.

This takes you to the formula of, F = (pi * Rsquared) * cylinder pressure, which leads you to the amount of force applied to the face of the check valve.

Pretty good return spring.

Have Fun!

Chris
repaired four Sam Yangs that were problematic especially for the hand pumpers

spring loaded the check, no more troubles