Reg pressures relationship with cylinder pressure.

[Fram]

Hi all,

This maybe a noob question but just trying to get my head around it.

Am I correct in thinking that, if for example, your reg is set to 100 bar, as long as your cylinder pressure is above 100 bar your reg works as intended, but when your cylinder pressure drops below 100 bar then the reg drops off as it can not maintain its set pressure

I imagine the above scenario is very simplistic but in essence is that generally how it works

Many thanks
Fram

 

[Meal Dot]

In simplistic terms, you are correct.

 

[Wing Commander]

Yes, you are correct.
Some rifles have twin gauges to show the different pressures in the reservoir and the regulator.

This one is from Prophet 2.
The main bottle can be charged to 300 bar. . The regulator runs at about 48 bar.
As long as there is sufficient pressure in The main tank, it will keep running at 48 bar.

 

[Fram]

Ahh, that explains the double gauges

so basically I would refill rifle before it gets to 100 bar in the cylinder to maintain regulated shots or realistically count how many shots I get on reg.

Many thanks chaps

 

[Pete2]

If set up correctly, when the cylinder pressure drops below reg pressure, there will not be a spike in velocity and it will remain at the same FPS as when on reg for the next few shots then start to drop.

 

[Fram]

That’s interesting, if the reg needs a certain pressure to “open” to let in the air from the cylinder, does the gun stop firing when this pressure drops too low to open the reg?

 

[E30_318is]

That’s interesting, if the reg needs a certain pressure to “open” to let in the air from the cylinder, does the gun stop firing when this pressure drops too low to open the reg?

No - once the reg can't maintain the pressure it's set to (because that pressure isn't available) the reg essentially becomes bypassed, the gun will shoot as it would if the reg isn't there, so you'll be able to fire until the valve can no longer be kept closed (usually hammer preload overcoming EV return spring, with no pressure on the cylinder side to push it back) then it'll dump it's air.

I believe it's the desired target pressure that closes the reg, rather than opening it. Once the output pressure is high enough to compress the belleville washers, the reg closes.

 

[rockdrill]

That’s interesting, if the reg needs a certain pressure to “open” to let in the air from the cylinder, does the gun stop firing when this pressure drops too low to open the reg?

It's the other way round, the regulator closes off when the plenum (firing) pressure reaches the regulator setting.

When cylinder pressure fall below reg pressure it won't close off the plenum from the main cylinder.

 

[Fram]

Brilliant thank you chaps that makes perfect sense.

Especially the reg opening and closing thanks rockdrill

 

[Balders]

Beware that firing after the reg pressure is below the set pressure that the gun may vent the cylinder.
If that happens it's because the hammer spring can now open the exhaust valve as it's not fighting the pressure.

 

[zZ WIGGLY Zz]

And also depending on hammer spring tension you can damage the valve if you run to low reg presure. Manufactures don't normally advise running below reg presure..

 

[Fram]

Good to know chaps thank you, when I get my rifle in a months time I will spend quite a bit of time getting to apply this stuff in a practical way, just trying to get a head start on the theory

 

[sagalout]

Simples guide

 

[Fram]

That’s really helpful thank you