Filling PCP's and " Dive cylinders"

[Scub]

I have noticed that there are some questions about charging PCP's that keep popping up, so I thought that I'll give you my take on things.

Bottle or pump ??

For all the guns with a small ish tank, it is not realy worth getting a scuba cylinder as charging them up is not going to take more then 2 minutes. That is of course when it has been filled for the first time from zero bar and just needs to be topped up from say 120 to 190 bar.
The guns that I am on about for using a pump are the likes of BSA ultra and its relatives and the AA 200 and 400 series and the like. One important thing about getting a pump is, that it should have a decent filter and a so called " dry pack " as this stops dust and moisture getting in the internals of the gun that will cause corrosion and may damage the valves and seals.
For guns with larger tanks on them, a dive bottle is the better option, unless you write the sport as in sport shooter in capital letters because filling one of them is like an evening pushing weights at your local fitness studio. In my case ..... after filling one of them with a pump, I just want to go to bed and sleep for a week and leave the hunting for the next week end. So that's not an option.
What bottle to get??
There are a multitude of different cylinders on the market these days, ranging in size from 3, 5, 7, 10, 12, 15 and 18 litres and working pressures are 200 and 300 bar. IMHO a 300 bar 10 or 12 litre cylinder is out of that lot the best choice, because they are not that heavy compared to the 15 and 18 litre bottles that can be a straight 12 on the hernia scale ( and that only goes to 10 ) but you still get a decent number of fills out of them. If you have some cash and don't know what to do with it, you could get a 5 litre 300 bar bottle to take along to top up your gun after you have shot your 300 th wabbit on a Saturday afternoon and your shots start to drop a bit.
Keep in mind though, that not all dive shops will be able to fill to 300 bar, so it would be a clever thing to do to go and ask them before you go out and by a 300 bar cylinder. If they can't fill to 300 bar, get a 12 0r 15 litre 200 bar cylinder. On most of them it states 234 bar. The trick here is, that they will as a rule fill a 200 or 234 bar cylinder to around 210 to 220 bar and depending on how fast they fill it, by the time it has cooled of you are going to be left with around 200 to 210 bar when you take it home. So you are not going to get as many fills out of it as you may think.
There are two kinds of valves on air cylinders. the A clamp and the DIN fitting. A clamps a used on cylinders of up to 232 bar and the DIN for anything above that. You can however find DIN on the cylinders of 200bar and up but you should not use A clamps on anything above 232 bar as they are not rated for higher pressures but you can get inserts that will convert a DIN valve to A clamp. They are just threaded bungs that can be screwed in to the valve using a 8mm alan key.
When using a 300 bar cylinder, do not under any circumstances use the pressure gauge on your gun to check the pressure of your fill, because the gauges on most guns have such a small hole in that back to measure the pressure that they respond in a rather slow way and ou may well get way to much air in there and ruin your gun while filling. So a gauge at the dive cylinder side is a must.
No matter what cylinder size or pressure rating you get, you will have to have it inspected and tested 5 years after it has been made and thereafter every 2 years. That can cost anything up to 40£ per test. Prices for filling a dive cylinder vary from 5 to 15£ a pop so you will have to go and find that out for yourselves.
No matter if you fill your gun from a cylinder or pump it up, the last thing you want in the internal workings is those M & M's....... no the coloured ... not sweets. I am talking about Muck and Moisture. So keep all the bits like connectors and the like clean.
Another question that keeps popping up is " How many fills do I get out of a dive bottle." here is one example to work it out.

You have 300 bar in a 12 liter bottle of that you can use 100 bar as you are filling to 200.

So 12l X 100 bar is 1200l

The AA410 has i think a 150 cc tank, so 150cc times 100 bar is 15l ( because you are filling from 100 to 200 bar )

so 1200l / 15l = 80 fills

Now if the cylinder size of your gun or your diving cylinder is different just change that in the math bit and you are sorted.
Now Albert Einstein and Co will say " Hang on a minute I am filling the hose from zero every time I fill my gun up so where does that go" It goes PPPFFFFFFTTTT as this is only a guide and not a way of working it out right down to the last fill so give it plus minus 10 fills or so. Because most of us fill to 190 bar from 110 etc. But working it out this way is a start when you have a look at what bottle you want to buy.

Hope that cleared up a thing or two about filling PCP's

[macka_smacka]

Hi mike that is a good write mate and deserves a sticky IMO one thing i would like to know... Do you know anything about CO2 filling ? i ask because ive found some 88gram refillables on the net. i know they have to be weighed as they are liquid CO2. just wanna know if its cost effective as those "use once" can be pretty pricey if you use it a lot.

Cheers

Macka

[HW100 Hunter]

That's some good info there mate much appreciated.

[Scub]

Hi mike that is a good write mate and deserves a sticky IMO one thing i would like to know... Do you know anything about CO2 filling ? i ask because ive found some 88gram refillables on the net. i know they have to be weighed as they are liquid CO2. just wanna know if its cost effective as those "use once" can be pretty pricey if you use it a lot.

Cheers

Macka

To be quite honest, if you are doing a fair bit of shooting, CO2 is not the way forward.
If you use air to fill them, the shot count is very much on the naff side.
If you have them filled a technical gas supply place, its not that cheap either and the costs involved, decanting of you own jay bottle is over the top as well.

[i8allthepies]

Thanks for an interesting read. Good stuff

[Brecks]

I have the FX fast pump for My Daystate MK4S and it does take a bit of effort over the last few bars but no big deal.

[simply james]

the pumps are ok if you fit enough

[D4V1D]

I've just brought a pump and was surprised how easy it was to pump up to 200 Bar. I got a bit sweaty though.

[r33ryan]

ive got a hills pump, easy enough to get to 190 bar but get a bit warm. good for those cold winter mornings

[Tonto]

Not knowing anything about pcp guns how do you know when the correct pressure is in the tank? Is it a case of 'how many pumps' or are there guages built in to the gun/pump? This may seem like a stupid question but I am of the old school, 'If you don't know, ask!' I have also seen mentioned filters, and 'dry packs' can someone explain this to me. (Email if you prefer) Thanks for looking Kimosabe - Tonto