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Thread: Handy tables and charts.

  1. #31
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    And it's Rich, by the way, not Rob.

  2. #32
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    Quote Originally Posted by Rich View Post
    The 232 bar point would indeed be near enough, an error of about 3 percent I think.
    The error at 300 bar is still only around 8 percent.
    Sorry Rich, but I don’t know where these percentages came from (or to what they refer). As I mentioned before, thermodynamics isn’t really my thing but, ‘Standard’ air behaves as the Ideal Gas that your model assumes at around 232 Bar. Above or below that pivotal pressure a mass-to-pressure error exists - below 232 Bar, the vessel’s pressure drop is slightly less than the Ideal Gas assumption anticipates; at higher pressures then the pressure drop is progressively much greater than your assumption would anticipate. Unfortunately, in the real world, the greater-than-anticipated pressure-drop means that at every iteration (fill) the pressure discrepancy increases and so, by cascading that error, there are considerably fewer fills to be had.

    Quote Originally Posted by Rich View Post
    As I said, it hasn't led to complaints from users - only yours, Dave.
    I haven’t complained. Far be it for me to complain. I’m just flagging an error.

    Quote Originally Posted by Rich View Post
    Compressibility is actually also temperature dependent so unless yet another input parameter is called for, it's going to have to be an approximation.
    Indeed it does but the temperature range we’re considering is comparatively small. Any temperature variation would apply equally to both models anyway.

    Quote Originally Posted by Rich View Post
    And it's Rich, by the way, not Rob.
    Noted and corrected. Sorry about that.

    ATB
    Dave
    "Only two things are infinite, the universe and human stupidity, and I'm not sure about the former." Albert Einstein.

  3. #33
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    Perry's Chemical Engineers' Handbook. I can't give you a page reference, I no longer have a copy. It was a useful document when I was in industry.

    Compressibility varies by around 5 percent between 250K and 300K, say one percent per 10K variation. 232 bar at factor 1.0 is true at 250K, maybe 3 percent adrift at "room" temperature. That is why I estimated a 3 percent error at the "base" point.

  4. #34
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    It's academic when you don't know the length of line used to fill the cylinder. We also don't shoot at a fixed temp... i think last year I covered 35 degrees.

    I don't think anyone is going to get upset about the fill count not meeting x person's predictions... the benefits of 300 are that if your shooting at 200 bar you can hold a lot more air in the same volume for a longer amount of fills.

    Reminds me... I need to get my 3L filled... i've forgotten how many fills it's done... but it's down to 185 and i'm scrounging air. Even though I shoot almost every weekend, and regularly each week, I can't for the life of me remember how many fills I get out of my 4 pcps... all with different sized cylinders.

    Rob, not Rich

  5. #35
    tomosmond is offline My name's Osmond and I've got a little Jimmy
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    will they open with open office. Im downlading it at the moment and just wanted to know.
    AA S400 (LH) - Tasco Custom Shop 8-40x56 - Rowan engineering trigger - UK Neil hamster & air stripper
    Steyr LG100 (LH) - MTC silver viper 3-12x44

  6. #36
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    Tom, yes, I just tried it and it seems to work OK

    Number of fills does not contain any macros.

  7. #37
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    Am I Legal also seems to work fine.

    I haven't checked them side by side with Excel but no error messages came up.

    Am I Legal also has no macros, the maths is done with Excel built-in functions.

  8. #38
    tomosmond is offline My name's Osmond and I've got a little Jimmy
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    thanks snock and rich
    AA S400 (LH) - Tasco Custom Shop 8-40x56 - Rowan engineering trigger - UK Neil hamster & air stripper
    Steyr LG100 (LH) - MTC silver viper 3-12x44

  9. #39
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    As you shoot an EV2 I am surprised it is not in the list.

  10. #40
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    At the moment I'm waiting for some more details to come in from one or two manufacturers and when I have it I will be releasing a version with more current rifles in the list. The EV2 will be included.

    For the moment, anyone with an EV2 can "pretend" it is a S400 classic for this purpose as they share the same reservoir tube.

  11. #41
    carld41 is offline I deserve everything I get
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    Good thread

    Brilliant Thread Rich, Lot of work for something that's FREE.
    I for one applaud you
    All the best
    Carl

  12. #42
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    Thumbs up

    Quote Originally Posted by snock View Post
    OK, thanks to Rich for creating and providing the following excel spreadsheets for general use.
    He created this spreadsheet so that anyone can input the appropriate data to find out how many fills per scuba tank they'd get from their kit.

    How many fills.

    The second link gives the user the chance to see, with any given variation, how likely they are to exceed the 12ft lb legal limit.

    Am I legal?

    Pete.

    Pellet list table 1.
    Pellet list table 2.
    Pellet list table 3.
    V.handy...thanks very much

  13. #43
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    |Thank you for the very useful charts I've printed them off to take to the club.

    ken

  14. #44
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    Thumbs up

    Quote Originally Posted by BSAlightning_XL View Post
    V.handy...thanks very much
    I second that great job......

    Noticed that just the EV2 missing on the fill chart but i worked round that and can add this test i have done myself on my EV2 resulting in :-
    300bar bottles all 3 sizes 3lt, 6ltr, 12ltr, bottles
    fill upto 200 use untill 95 then refill to 200
    from my 3ltr bottle i got 10 fills
    from the 6ltr bottle i get 22 fills
    and from the 12 ltr bottle i get a whooping 36 fills

    hope this adds to the already impressive list compilled for anyone that has an EV2 might be my gun but these were tested over last week and this week as i thought why not combine the two with my new scope setup to get them setup right and i had nothing else to do so thought why not add something to this forum also averaged 112 shots per fill and had a lot of fun dropping targets and woodies and a few rabbits over 2 weeks all useing the same gun but keeping a check on the shot count and refill count
    cheers Andy
    Not enough space to write the collection but 5 gun cabinets and a big shed does the trick
    "SHOOT IT, SKIN IT, COOK IT, EAT IT " and my favourite only a blind man says "i cant see the target in my scope" and is telling the truth

  15. #45
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    I'm co-operating with another party to do a significant expansion of the list of rifles. We rely upon manufacturers supplying timely and accurate data; I don't want to make lots of little changes and additions, just one big one to bring it all up to date and fresh.

    Version 22 is the latest and has the EV2 included, as well as the Steyr LG110 and the BSA Ultra.

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