Can you use Nitrogen in a HPA tank

[MorganL]

I'll start off with I'm a complete HPA noob, I've just bought a conversion kit for my TM MWS CQB Block 1 & hence have a small HPA tank now that I need to fill up, there are a couple local dive clubs near me and obviously I can fill it up at my next game but outside of that I'm thinking what is an easier way to fill it up, I have access to an absolute ton of Nitrogen (I own a Fibre Laser) so on hand I have around 1,000L of 300 bar Nitrogen, what would the implications of using nitrogen instead of CO2 in the HPA tank? 

 

[Dan Robinson]

Well you're only losing 21% oxygen,  so barring potential condensation issues (cant recall hpa users mentioning this), the only other advantages would be convenience for you.

You have it for free so great... otherwise it's like having the premium air option for you car tyres ?

 

[Rogerborg]

CO2 in the HPA tank? 

Air in the HPA tank.

Which handily illustrates that we already use (at least) three kinds of compressed gas in our spud-guns.  I can't think of a reason why the type of gas particularly matters, just the expansion.

 

[Lozart]

As long as you keep on top of your maintenance (not sure if the nitrogen would be better or worse for any seals in the system) then I see no reason why not. It can't be any more aggressive than the propane you'd have been using prior to converting it to HPA!

 

[MorganL]

As long as you keep on top of your maintenance (not sure if the nitrogen would be better or worse for any seals in the system) then I see no reason why not. It can't be any more aggressive than the propane you'd have been using prior to converting it to HPA!

That was my thinking, nitrogren is actually a non-reactive gas it doesn't interact with anything, you can fill your car tyres up with it infact I'm sure racing car tyres are filled with it. Also as it's innert its safe to vent into the atmosphere unlike propane also in most cases it prevents oxidisation so should in theory be really good for the internals. 

Mainly I was making sure I wasn't being completely stupid in why we use compressed air apart from the fact its easier to produce with a compressor etc... 

 

[Lozart]

its easier to produce with a compressor etc... 

That's literally it.

 

[Tommikka]

Just to be sure as you mentioned CO2……

You are using an actual HPA cylinder aren’t you as opposed to a CO2 cylinder ?

View attachment 134299

HPA cylinders are topped off with a regulator assembly incorporating burst discs, pressure gauge, fill nipple and output valve.

Whereas CO2 cylinders have a combined input/output valve with potentially an on/off.

Assuming it is HPA then nitrogen will be fine, it’s cleaner than air (of which nitrogen makes up the majority)

Back in the day as paintball (mostly) migrated from CO2 to compressed air nitrogen was often used instead from bulk cylinders until sites invested in HPA compressors.

 

[MorganL]

Just to be sure as you mentioned CO2……

You are using an actual HPA cylinder aren’t you as opposed to a CO2 cylinder ?

View attachment 134299

HPA cylinders are topped off with a regulator assembly incorporating burst discs, pressure gauge, fill nipple and output valve.

Whereas CO2 cylinders have a combined input/output valve with potentially an on/off.

Assuming it is HPA then nitrogen will be fine, it’s cleaner than air (of which nitrogen makes up the majority)

Back in the day as paintball (mostly) migrated from CO2 to compressed air nitrogen was often used instead from bulk cylinders until sites invested in HPA compressors.

this is my tank 

Got my wording mixed up meant shop air not CO2. 

From what I can see apart from the risk your life aliexpress compressors HPA compressor are dead expensive. 

 

[Tommikka]

this is my tank 

That’s good for HPA and / or nitrogen 

Got my wording mixed up meant shop air not CO2. 
 

From what I can see apart from the risk your life aliexpress compressors HPA compressor are dead expensive. 

Yep.  The optimum is to fill on site with a ‘proper’ high pressure, filtered & maintained compressor which runs into the thousands of £

Cheaper compressors are available now (not workshop ones) can do the job these days without killing you, there are also 

Your plan to use existing nitrogen facilities is a fair one

Viable alternatives for those who need their own fill system are typically a scuba cylinder rig or a ‘shoebox compressor’ which takes input from a workshop type compressor then boosts up to 3000psi etc - but that is slow & noisy

A compromise is a high pressure stirrup pump - relatively cheap (ensure a filter is added) but takes time and effort 

Your existing nitrogen is a good call, clean & convenient 

 

[MorganL]

That’s good for HPA and / or nitrogen 

Yep.  The optimum is to fill on site with a ‘proper’ high pressure, filtered & maintained compressor which runs into the thousands of £

Cheaper compressors are available now (not workshop ones) can do the job these days without killing you, there are also 

Your plan to use existing nitrogen facilities is a fair one

Viable alternatives for those who need their own fill system are typically a scuba cylinder rig or a ‘shoebox compressor’ which takes input from a workshop type compressor then boosts up to 3000psi etc - but that is slow & noisy

A compromise is a high pressure stirrup pump - relatively cheap (ensure a filter is added) but takes time and effort 

Your existing nitrogen is a good call, clean & convenient 

Now I just need to work out the best way of getting it from the regulator into the tanks filling nipple, I'm sure google has some sort of adapter . 

 

[Tommikka]

Now I just need to work out the best way of getting it from the regulator into the tanks filling nipple, I'm sure google has some sort of adapter . 

This sort of thing is used as a fill rig for scuba to paintball / airsoft cylinders 

https://www.bzpaintball.co.uk/hk-army-a-clamp-yolk-fill-station-blue

If filling from low or empty then fill a little, stop and pause, fill a little more and repeat.  That ensures it’s nice and slow and reduces heat generation 

If you fast fill from empty then not only are you increasing the risk of overfilling but gas expands when hot - when it cools the pressure will drop which means a fast hot fill ends up with less of a fill

 

[MorganL]

30 minutes ago, Tommikka said:

This sort of thing is used as a fill rig for scuba to paintball / airsoft cylinders 

https://www.bzpaintball.co.uk/hk-army-a-clamp-yolk-fill-station-blue

I've seen those scuba adapters on a youtube video that was the cheapest method I could find if you had an old tank kicking around but even on FB or ebay you can pick them up pretty cheap. 

The nitrogen bottles have a 5/8" fitting on which then goes off to the regulator, 

However this that one in question is £800 lol I'll give my supplier a ring on Monday and see if they'll loan me one or chuck me a freebie, that reg is a high pressure the one we use is a High Flow which cost 3x as much and its massive as it has a heat exchanger when cutting full speed even the bottles start freezing up lol. 

I know these tanks are designed for the pressure but they must be dead thick 1800psi is not to be sniffed at. 

 

[Tommikka]

I've seen those scuba adapters on a youtube video that was the cheapest method I could find if you had an old tank kicking around but even on FB or ebay you can pick them up pretty cheap. 

The nitrogen bottles have a 5/8" fitting on which then goes off to the regulator, 



However this that one in question is £800 lol I'll give my supplier a ring on Monday and see if they'll loan me one or chuck me a freebie, that reg is a high pressure the one we use is a High Flow which cost 3x as much and its massive as it has a heat exchanger when cutting full speed even the bottles start freezing up lol. 

I know these tanks are designed for the pressure but they must be dead thick 1800psi is not to be sniffed at. 

That does look similar-ish to a 5/8” DIN fitting, but DIN fill rigs don’t have that nipple.







A word with your supplier is the best option 

 

[Rogerborg]

this is my tank

There are many others like it, but this one is yours.

 

[Tommikka]

There are many others like it, but this one is yours.

….: and some of mine

View attachment 134327

In the order of dead, nearly dead and their baby

Dead had a final of 2019/09

Nearly dead has a final of 2025/01 but is out of test so I’ve sacrificed it as not worth testing for the number of games planned

Their new baby awaits a new regulator (I was half considering a regulator transplantation but have opted for brand new giving me the benefit of fresh lightweight, customisable output, and peace of mind that burst disks won’t be giving up the goat)