Handy tables and charts.

[snock]

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.

[bmhill]

how good is that?
cheers rich and snock

[snock]

Thanks.

Feel free to save them onto your PC.

[A16NS V]

Out of interest is there any way of adding guns to the drop down list? I assume they ar ein a look up table somewhere?

EDIT : I've just found them. Although I don't understand how the formulas work to insert an Ultra. It's resovoir is 50cc IIRC

[big gav]

I dont have xcel , any chance of posting it up in Word mate?

[snock]

Out of interest is there any way of adding guns to the drop down list? I assume they ar ein a look up table somewhere?

EDIT : I've just found them. Although I don't understand how the formulas work to insert an Ultra. It's resovoir is 50cc IIRC

The program was written some time back, so certain newer models won't be listed, I'm afraid.

I dont have xcel , any chance of posting it up in Word mate?

Sorry mate, not by me there isn't.
If you post what gun, hose, pellet, fill pressure etc., someone will input the date and give you a reply.

[Andy Bee]

Am I legal?

Thanks,
Excellent spreadsheet. I added another tab to build a database for my rifle. I'm shooting a Co2 rifle (first time with Co2). The spreadsheet has been invaluable to track performance vs the pressure changes as I use the gas, or prove/ disprove what I've read about Co2.

I've got the fps/ ft/lbs/ joules (energy) logged for different pellet gr weight. Next job for me is to make something to measure the pellet energy at the poi 20yd - 40yd.

Now my of knowledge of physics ends and my experimental mind starts starts. 1 lb weight / 12 inch pendulum, a pencil to describe an arc.

[Harry's Lad]

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.

That’s a reasonable first guess but a little naïve. It assumes that air is infinitely compressible and behaves as an Ideal Gas . Unfortunately, that is not the case. Consequently, the model will slightly underestimate the number of fills if the bottle pressure is less than ~232 Bar and progressively overestimate if it is greater.

e.g.,

‘Calibrating’ the spreadsheet with bottle volume=6 Litre, Bottle Pressure=232 Bar, Rifle Fill Pressure = 200 Bar, Rifle Bottle Volume=200 cc (AA S410 Standard), ‘Empty’ Pressure = 120 Bar and ‘Standard’ hose type (10 cc) gives an estimated 10 fills. Changing the only Bottle Pressure to 300 Bar suggests 33 Fills.

Entering the same data into FillCalc (which has the Van de Waal corrections applied) yields 10 fills and 24 Fills @ 232 Bar and 300 Bar respectively.

I guess that most folk use 232 Bar bottles anyway (so the increasing discrepancy above 232 Bar is fairly academic) but please be aware that, if you’re considering a 300 Bar set-up, you’ll get considerably fewer fills than this spreadsheet suggests.

ATB
Dave

[snock]

Naturally you're going to suggest Chairgun is more accurate, Dave (), but as I'm not so inclined to trawl through volumes of physics books to discover which table is more accurate, I'll let the creator of the table speak for it.

[Harry's Lad]

Naturally you're going to suggest Chairgun is more accurate, Dave (),

Sorry, I tried not to make it read like that. An earlier version of FillCalc used the same model as the spreadsheet and – although I was vaguely aware of air’s compressibility issues – I didn’t consider them particularly relevant (but then thermodynamics was never really my thing ). However, as demonstrated, the differences above ~240 Bar are too big to be ignored. ….

. . . but as I'm not so inclined to trawl through volumes of physics books to discover which table is more accurate, I'll let the creator of the table speak for it.

No need for any books (or trawling through same), just Google ‘Van der Waal’, it’s there for all to see. Consider the post as a simple warning that the number of fills from 300 Bar may be found to be misleadingly high.
Having said all that, the Van der Waal model is a pig to work with (assuming the linear relationship is much simpler) and the differences are pretty much irrelevant under the magical ~232 Bar level.

HTH
Dave

[Edit] By the way, did you ever wonder why 232 Bar is/was a popular working pressure for a pressure vessel? Why 232 Bar; why not 225 Bar or even 250 Bar? It turns out that 232 Bar is the pressure (for air) where the Ideal Gas approximation holds true. At pressures below that you get slightly more than you expected; at over 232 Bar you progressively get a lot less; the compressibility ensures that the Law of Diminishing Returns takes hold with a vengeance.

[Rich]

Being the original author, let me say that I am and was at the time aware that the maths were simplified and ignored the Van Der Waal issue, rather like the earlier versions of Chairgun and other ballistic software had simplified approaches to residual energy and trajectory.

Number of Fills was released at a time when money was being raised by members of this forum to support breast cancer charities, and the spreadsheet was given away on the basis that recipients who found it useful would make an appropriate donation. I have the papers on file somewhere, as I dare say the posts and threads from that era have long gone. We made about £170 for breast cancer charity on the first evening; I recall sending about 75 emails with a copy of the spreadsheet attached, before I went to bed at 2am.

There seems to be little point in re-releasing number-of-fills as pretty well everyone these days will choose a 300 bar bottle over a 232 so long as they can get it refilled relatively easily. The cost of getting to the filling shop is for many the largest single factor, so it makes sense to buy the biggest and highest pressure bottle you can manhandle.

If I were to update it, I would not bother with a true Van Der Waal correction, but simply use the present elementary maths substituting an arbitrary value of something like 285 bar whenever the user thought they were selecting 300 bar. That would give a closer approximation. In any event the accuracy is affected by whatever allowance is made for dead volume in the hose and gauge, and experience has shown me that some decant sets are far more wasteful than others.

The other factor to consider is that number-of-fills has a look-up table with the reservoir capacities for several popular rifles (and that's out of date now too.) Readers may think that getting the reservoir capacity from the manufacturer only requires a phone call. In practice one firm steadfastly refused to let me have the information declaring it was a trade secret. I ask you, how can it be a trade secret of any worth when firms such as Theoben specify the size of the buddy bottle?

The example of the S410 with 200cc is actually incorrect as later information has shown this reservoir to be 216cc. The carbine and export models have also been amended.

If I could move to the am-I-legal spreadsheet, I do commend this to all members especially in the light of current issues regarding rifles approaching the legal limit. This time the maths part does not rely on any science or engineering, it's purely a matter of statistics, more specially probability.

An over-the-counter chronograph will have an accuracy of something like plus or minus 1 percent of reading. The owner will not know whether his chrono reads high, low, or spot on. The chrono used by the Home Office testing station will be a precision piece of kit and will have a calibration certificate, with a tolerance of something like 0.4% of reading.

It would be possible for your domestic chrono to be at one end of its limit and the testing station chrono to be at the other end of its limit, a variation of 1.4%. Remember that the chrono measures velocity, but it is muzzle energy that is specified by law. As there is a square function from velocity to energy, 1.4% variation in velocity equals 1.96% variation in power.

The maths part looks not only at the rifle's velocity but the consistency of that velocity. It is the case that a rifle that is inconsistent is more likely to throw a rogue high value at some time. That is why the spreadsheet can give you the surprising and maybe unwelcome answer that ten or even twenty shots close to the limit (but all under it) bring a risk of failing a Home Office test if the rifle is inconsistent. When it says, there is a 3 percent risk of failing a test, think of it this way. You and 32 friends line up to have your rifles tested, all supremely confident that your trials at home have kept you under the limit, albeit close to it. One of you will be disappointed to learn that you are in possession of a section 1 firearm, without a licence.

Rich

[Harry's Lad]

Being the original author, let me say that I am and was at the time aware that the maths were simplified and ignored the Van Der Waal issue, rather like the earlier versions of Chairgun and other ballistic software had simplified approaches to residual energy and trajectory.

The first ChairGun version, as it evolved through several iterations, was an adequate model of airgun ballistics as used in the context of airgun usage at that particular time. ChairGun2 evolved from a different ballistic model that more accurately met different (and more challenging) criteria – mostly driven by the requirement of long-range shooting in Oz and the USA. In both cases, the software operated accurately within its stated restraints.
That’s the difference; your spreadsheet is capable of giving results that, because of the known and ignored oversimplification, are erroneous. I was simply pointing out that, given the deficiencies of the simple model used, the 232 Bar + results may be seriously in error.

There seems to be little point in re-releasing number-of-fills as pretty well everyone these days will choose a 300 bar bottle over a 232 so long as they can get it refilled relatively easily. The cost of getting to the filling shop is for many the largest single factor, so it makes sense to buy the biggest and highest pressure bottle you can manhandle.

Perhaps that’s a good reason for re-doing/releasing the spreadsheet since it is the > 232 Bar predictions that are in error. The conjecture was, on acquiring a 300 Bar bottle on the basis or your spreadsheet, that the punter could be very disappointed in the number of fills realised.

If I were to update it, I would not bother with a true Van Der Waal correction, but simply use the present elementary maths substituting an arbitrary value of something like 285 bar whenever the user thought they were selecting 300 bar. That would give a closer approximation.

You could do that . . . or you could do it properly although writing an accurate working algorithm in VBA could be quite challenging.

In any event the accuracy is affected by whatever allowance is made for dead volume in the hose and gauge, and experience has shown me that some decant sets are far more wasteful than others. The other factor to consider is that number-of-fills has a look-up table with the reservoir capacities for several popular rifles (and that's out of date now too.) Readers may think that getting the reservoir capacity from the manufacturer only requires a phone call. In practice one firm steadfastly refused to let me have the information declaring it was a trade secret. I ask you, how can it be a trade secret of any worth when firms such as Theoben specify the size of the buddy bottle? The example of the S410 with 200cc is actually incorrect as later information has shown this reservoir to be 216cc. The carbine and export models have also been amended.

True. But then, we can only use the data that we’re sure of. Otherwise it’s just GIGO again.

ATB
Dave

[BSAlightning_XL]

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

[pcken]

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

ken

[madandy]

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