Results 1 to 15 of 15

Thread: Does temperature affect pressure in pcp rifles?

  1. #1
    Inactive Member

    User Info Menu

    Default Does temperature affect pressure in pcp rifles?

    Hallo everybody. I've heard that when a rubberduck boat is inflated while the temperature is cool, you have to check the pressure of the pontoons as the day gets warmer. As the temperature increases it will increase the pressure in the pontoons of the boat. Does the same rule apply for pcp's? For example filling your pcp at home in the morning while it is cool and driving with it in a vehicle, will the pressure increase as the temperature increases or is the volume of air to small to make a difference? This is my first pcp and i don't want to learn the hard way. Thanks.
    Sign Up To Air Rifle SA Forums

  2. #2
    Sharp Shooter
    SAFTAA FT Colours '10

    User Info Menu

    Default

    mmm.. yes temperature does cause change in ap but.. and you guys need to help me here.. a CO2 rifle works differently to a PCP. in CO2 the presure falls of rapidly and one of the rifle's inherent qualities is that CO2 is self regulated (at about 750-800 psi?). Less Expensive PCP's (ones that dont use regulators) use the air presure to control the amount of air let out the valve. sooo yes temperature does effect air pressure but where as, on a cold day it would be like you start on your second shot with a PCP and on a hot day maybe fill it a fraction less so you start at the presure your first shot usually starts, CO2 will have a bigger diffrence as the CO2 is used as a regulator.

    so in other words. on a pcp change in ap is neglagable to shot consistancy but on a co2 it will have an effect
    Sign Up To Air Rifle SA Forums

  3. #3
    Marksman
    The Guru

    User Info Menu

    Default

    unfortunately Co2 being self regulated on the one hand is very temperature sensitive and the regulation goes out of the window due to very significant velocity shifts with temp changes.

    Air PCPs will not shift in varying temperatures due to cylinder pressure changing...this is entirely negligible.
    They may have velocity and POI shifts for other mechanical reasons when the temp changes though
    Sign Up To Air Rifle SA Forums

  4. #4
    Sharp Shooter
    SAFTAA FT Colours '10

    User Info Menu

    Default

    so.. guido, you aggree the best way to go with a co2 rifle is to use hpa cause that, by being high presure air that is regulated down to co2 level will always be consistant in the presure it delivers. and on a pcp it does nto realy matter ( depending on the quality of the internals..) but if you want to go overboard you can add a regulator to the pcp to simulate the HPA benifits?
    Sign Up To Air Rifle SA Forums

  5. #5
    Sharp Shooter

    User Info Menu

    Default

    Rowan, to date there have been very few accidents with PCP's and those that did happen could usually be attributed to idiots filling with alternative gases. Use the real stuff and you'll be fine, if your worried about it, blow off a couple of Bar when it gets hotter.
    Sign Up To Air Rifle SA Forums

  6. #6
    Inactive Member

    User Info Menu

    Default

    Thank you for the replies. Something less to worry about when out plinking. Brian, for sure, only air!
    Sign Up To Air Rifle SA Forums

  7. #7
    Sharp Shooter
    Doctor BAM

    User Info Menu

    Default

    Rowan
    I see you are from Oudtshoorn..... Now that is a place that can get warm, make no mistake....!!!!! Whatever has been said by others, I can tell you it will make a difference if you fill the PCP in an air-conditioned room and then start shooting in bright sunlight at 12 o'clock in the summer in Oudtshoorn.....!!!!!
    It all depends how the rifle is tuned and how close to 'valve-lock' you were when you charged the rifle..... Keep the rifle in as much shade as possible when shooting, but be awawre of the fact that temperature will have an effect on the pressure.....
    If you think PCP's are sensitive, then multiply that factor by 10 for CO², because they are a nightmare, both for heat as well as cold......

    malan
    Sign Up To Air Rifle SA Forums

  8. #8
    Sharp Shooter

    User Info Menu

    Default

    it is not that bad malan.
    Sign Up To Air Rifle SA Forums

  9. #9
    Sharp Shooter
    Doctor BAM

    User Info Menu

    Default

    When last were you in Oudtshoorn, my friend.....????
    I was there on the 11th and 12th of January this year.....
    You cannot sleep at night, you just sweat your way through the dark period.....

    malan
    Sign Up To Air Rifle SA Forums

  10. #10
    Sharp Shooter

    User Info Menu

    Default

    I wasn't talking about the heat
    Sign Up To Air Rifle SA Forums

  11. #11
    Protea FT Team '07/'08/'09/'10/'11/'12/'13
    National FT Champ '09/'13

    User Info Menu

    Default

    The cylinder on your rifle is designed to withstand the variations in press due to temp changes, although I suppose you can push it close to the limits, in our harsh African conditions, if you leave it in a closed car in the sun, for long periods.

    My personal experience though, suggests that change of point of impact, is caused more by humidity, combined with cold temp, and barometric press ( air density), than by a " hot" rifle, but that is a science on it's own.
    Sign Up To Air Rifle SA Forums

  12. #12
    Inactive Member

    User Info Menu

    Default

    Thanks for your inputs, what i understand from your comments is that heat can have a influence on the pressure inside a pcp's cylinder, but it is designed to withstand the variations.

    But malan's point taken as well, do not take unneccesary risks. Thanks.
    Sign Up To Air Rifle SA Forums

  13. #13
    Protea FT Team '12/'16/'17

    User Info Menu

    Default

    i have put it to the test, filled the air cylender to 150 bar and put it into the over at 75Deg for 30 min the preasure only went up by 10 bar. our rifles and cylenders should never get to 75deg so the preasure change is nothing to worry.

    i did not shoot it at that tempreture so i dont know what the poi would be, tooooo scared of a boooooom.

    tempreture affects the stock more and with wood and alluminium the stock worps in fully ways so this should be the thing to look out for.
    Sign Up To Air Rifle SA Forums

  14. #14
    Sharp Shooter
    Doctor BAM

    User Info Menu

    Default

    Total DOM

    Thanks for clearing that up in the oven....!!!! Now the temperature in a car in Oudtshoorn can easily go up to 70 degrees in the sun, when you leave the rifle on the shelf inside the rear window.....
    If your fill value is close to your valve lock value, the extra 10 bar could easily show in the initial velocities you get out of the rifle.... For a regulated PCP, I can see that it would not be such a big issue and I agree with Guido that there could be other factors influenced by temperature, apart from the pressure inside the tube....
    Why are you scared to fire the Walther at 160 bar.....???? I thought you can normally fill to 200 bar, the regulator should be able to take care of it......?????

    malan
    Sign Up To Air Rifle SA Forums

  15. #15
    Protea FT Team '12/'16/'17

    User Info Menu

    Default

    i was scared to re attach the cylinder back to the rifle at 70 deg
    Sign Up To Air Rifle SA Forums


Similar Threads

  1. Low pressure pcp.
    By Froggy in forum Airgun Discussions
    Replies: 1
    Last Post: 13-09-13, 17:48
  2. Air pressure regulator for PCP
    By audriusize in forum Airgun Discussions
    Replies: 64
    Last Post: 27-02-12, 20:34
  3. Storage pressure of PCP
    By SarelCrause in forum Airgun Discussions
    Replies: 5
    Last Post: 14-01-11, 13:16
  4. Temperature effects on air rifles
    By Shayne in forum Airgun Discussions
    Replies: 5
    Last Post: 15-10-10, 09:04
  5. High Pressure Cylinders for Air Rifles
    By Janine in forum Airgun Discussions
    Replies: 69
    Last Post: 04-06-09, 21:50

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Friends of Air Rifle SA