So it is allright to charge the rifle with cold air?
PCPs change temperature in proportion to the ABSOLUTE (Rankine) temperature.... where (*R = *F + 460).... 20*F is 480*R and 70*F is 530*R.... If you charge a PCP to 3000 psi at 70*F and cool it to 20*F the pressure will drop to (3000 x 480 / 530) = 2717 psi.... It will then shoot a shot string like you started at 2700 psi (ie fewer shots).... If you charge it outside to 3000 psi at 20*F and bring it inside and let it warm up to 70*F, the pressure will increase to (3000 x 530 / 480) = 3313 psi.... Over that temperature range (50*F) the swing in pressure is about 10%....Bob
Quote from: rsterne on December 11, 2011, 09:47:02 PMPCPs change temperature in proportion to the ABSOLUTE (Rankine) temperature.... where (*R = *F + 460).... 20*F is 480*R and 70*F is 530*R.... If you charge a PCP to 3000 psi at 70*F and cool it to 20*F the pressure will drop to (3000 x 480 / 530) = 2717 psi.... It will then shoot a shot string like you started at 2700 psi (ie fewer shots).... If you charge it outside to 3000 psi at 20*F and bring it inside and let it warm up to 70*F, the pressure will increase to (3000 x 530 / 480) = 3313 psi.... Over that temperature range (50*F) the swing in pressure is about 10%....Bobyou are the man, every time i read on of youre posts where you start breaking it down to the math. it makes me feel like a 5th grader all over again learning fractions and other stuff i cant remember now that im 27
Would have to fill to 3K...lit it sit for a time to cool down to 20F...fill the dopped pressure back to 3K..let it sit...top it off.