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Thread: Foster Style Check Valve?

  1. #21
    Senior Member SeanMP's Avatar
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    Do you know the swept volume off the top of your head.

    Every extra 0.010 of groove will add 0.1cc
    Sean

  2. #22
    Moderator rsterne's Avatar
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    The swept volume is over 50cc.... However, the headspace should be a small as possible as it has a HUGE effect on the compression ratio.... The headspace around the stem of my check valve will only be about 0.05 cc.... so adding 0.1cc would be a 200% increase.... trippling the headspace will cost me about 60 psi inside the valve at 10 pumps.... and take an extra 2 pumps to reach 1500 psi....

    Bob
    Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
    Airsonal: Too many to count!

  3. #23
    Member Gippeto's Avatar
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    I see you've been busy with the math there Bob...have you calculated what effect a 6mm increase in stroke length would have?

    Al

  4. #24
    Moderator rsterne's Avatar
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    A 6mm increase in stroke would increase the pressure 28 psi in 10 pumps.... or take about 0.6 strokes less to get to 1500 psi.... Can you tell I made a pumper spreadsheet?....

    Pump swept volume is obviously important.... Headspace is more important at higher pressures.... It is the primary reason an F-T-P outperforms a conventional piston in a 13XX....

    Bob
    Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
    Airsonal: Too many to count!

  5. #25
    Senior Member SeanMP's Avatar
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    Quote Originally Posted by rsterne View Post
    A 6mm increase in stroke would increase the pressure 28 psi in 10 pumps.... or take about 0.6 strokes less to get to 1500 psi.... Can you tell I made a pumper spreadsheet?.... Bob
    I should have guessed that
    Sean

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