Divers bottles

[Guest Scuba1]

Right buddy I have added the bit you wanted to know to my original post on PCP filling joys.

 

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.

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 = fills

 

Around the neck of the cylinder there are some numbers and other markings.

On the top line there is the serial number of the cylinder and the name of the manufacturer. In essence there are only 2 companies that make steel diving cylinders on a large scale. One of them is Faber and the other is PST / Pressed Steel, so chances are that you will find one of those two names on your cylinder.

On the first part of the top line it states what the cylinder is used for and what working pressure it has. something like ( Compressed air or breathing air ) followed by the working pressure in bar.

The line below. states the empty weight of the cylinder in litre. followed by the material number and the test pressure. Then in the same line is the interesting bit. Makers stamp and moth and year of manufacture. The following tests it has undergone will as a rule be stamped into the the cylinder under this date, together with a stamp from the test centre.

The worst thing that can happen to a cylinder is to take it diving. So if you use yours on land only they are rated to have 10.000 filling cycles. That means that you can fill them to the working pressure and then empty them to 10 bar and fill them again to the working pressure. Taking into account, that most of you unlike me never empty your cylinders, you are going to get pretty much unlimited use out of them and providing that it gets filled with dry air, it should last you a life time if you don't keep it stored in the garden under some bush and let it rust away.

 

Some of you may moan at the 40 squid that they charge on average to test a cylinder but there is a bit of work involved and just for not letting anything out on this post, I'll give you a short sum up. First the cylinder to be tested has to be emptied. Then they have a look inside the thing with a light and a little mirror to see if there is any rust pitting. Then it is cleaned on the inside and filled with water right to the top then a valve is but into place and the cylinder's diameter is measured with no pressure on it. Now they put it into a water bath and put it under its test pressure and measure the cylinders diameter again. If it has not expanded to much it will have past its test now and has to be emptied and dried on the inside. Then the valve gets a new o-ring and is put back into place. If it does not pas the test it is cut in half to prevent it from being used again.

So that is where your 40 squid end up when you hand it over to the shop. Ohhh and they have to send it to a recognised test centre and back.

 

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.

One other thing: never ever use compressed oxygen to fill a PCP or you could find yourself in hunters heaven sooner then you may think, as oils and grease will explode when in contact with pure oxygen.

 

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

 

 

Happy hunting

 

 

Michael

[stealthy1 3,964]

Thats better, now people know how to sort the bottles exspiary date out, and can give it the spiel to dive centers, and maybe stop them from getting ripped off

[Guest Scuba1]

Thats better, now people know how to sort the bottles exspiary date out, and can give it the spiel to dive centers, and maybe stop them from getting ripped off

 

All we have to do now is get this thing dirty so it becomes sticky and I don't have to dig it out of the catacombs of thl every time a question about air cylinders gets asked.

So now its your turn stealthy to add some dirty stuff

 

ATB

 

Michael

[stealthy1 3,964]

Thats better, now people know how to sort the bottles exspiary date out, and can give it the spiel to dive centers, and maybe stop them from getting ripped off

 

All we have to do now is get this thing dirty so it becomes sticky and I don't have to dig it out of the catacombs of thl every time a question about air cylinders gets asked.

So now its your turn stealthy to add some dirty stuff

 

ATB

 

Michael

 

After the water shed

[Guest Scuba1]

Any other add ons you can think off stealthy?? As with the weather and myxi I am not getting out that much at the moment.