Discussion in 'General Airgun Chat' started by DeanB, Feb 6, 2019.
Can anyone tell me the volume of an EV2 reg?
That's pretty hard to do, as the chamber is made up both of the closed end of the reg and also of the closed end of the action, one has the firing valve in and the other the reg piston. Also there is the firing valve return spring which will take volume aways and in unmolested MK1's there is also a large plastic 'top hat' looking spacer on the end of the firing valve return spring.
Thanks for that explanation. How much air do you think is used to propel a pellet?
Depends on the pressure... ( i know that's not much help, but it does )
You can work it roughly for your gun by filling to say 200 bar and then firing 50 shots, then seeing what's left. Depends how precise your gauge is to read though. We did it with a digital one a while ago. From memory it was about 1 cc at 200 bar, but I might be wrong on that.
yep thats what our fag packet maths came up with .
More or less ........
100 shots from a 200 ish cc cyl toook us down from 200 to 100 bar ..................more or less .
so more or less 1cc per shot @ reg pressure of say 85 bar uses 85cc of air at atmosphere. ...............about double many springers !!!!
super approximate yes .........but it still made my brain ache
Thats the rule of thumb I've always gone by. It seems to roughly work on any PCP, regged or not and with any volume cylinder. I guess that means its the volume used per shot that is an indicator of its efficiency. Electronic Daystates for example will do 100+ shots for 100 bar used but the cylinder capacity is only about 140cc.
Made my brain ache as well, Phil, but...
200cc @ 200BAR = 40,000cc at atmosphere.
100 shots from 1cc regulator @ 85 BAR = 8,500c at atmosphere.
Residual air in cylinder = 31,500 at atmosphere.
Therefore, if the reg. was 1cc, residual cylinder pressure would be 157.5 BAR, rather than 100BAR.
200cc @ 200BAR = 40,000cc at atmosphere.
200cc @ 100 BAR - 20,000cc at atmosphere.
Air used = 20,000cc at atmosphere.
100 shots = 200cc air at atmosphere each.
200cc at 85 BAR = 2.35cc regulator volume.
I'll have to beg everyone's forgiveness if all this is wrong.
Agree with 2.35 cm3. That's just blown my calculations out of the sky. Unless the friction losses etc are high.
Just had a quick look at your calculations, Dean, and they're way over my head, but I did notice you had 21J equalling 28.5 ft. lb.
I've not looked at any calculations because the battery on my calculator is flat, but an EV reg will be running at 98 bar or above.
They can function at 85 but you are better off starting at around 100.
You are correct. Should be 15.5 ft lb. I'll correct it.
my airwolf fac when running at 12ftlb would use .3bar per shot, useless i know but at least i knew exactly how many shots i had left
Bob, do you know what is the reg pressure of the Airwolf when delivering 12 ft lb?
Fuckin hell Dean why are you asking Evo that he doesn’t know tomorrow is Friday.
Is it ?
Blimey that came round quick .
What’s scary mate is it’s already tomorrow in some places today.
I seem to remember this.. 100 shots used 100 bar on a 200cc bottle at 200 bar
As you say 100 cc at 200 bar is 20,000cc at atmospheric
So each shot uses 200cc at atmospheric
And if we say the reg is 85 then we end up with 2.35 cc which is much less than the regged chambers on the 12ft-lb rifles I’ve come across.
That said i think of it not as the volume doing the work but the pressure and the volume is needed to keep the pressure high while it does the work. If the volume was smaller the pressure would drop lower and push the pellet with less gusto.
It’s also important to remember that valves bounce so the amount going down the barrel might not be actually ‘used’ by the pellet, it might just be wasted.
Also another thing to bear in mind is flow doesn’t occur at the same time as a pressure wave/pulse which travels much faster and needs to propagate before flow occurs.
I don’t know what the calculations are but I can imagine the temperature affects how much energy the air has. If in reality we are only taking small amounts then perhaps that has a bigger effect than something which uses a lot more.