Nitrous Oxide Tank / Cylinder or Bottle Refilling,
How its done!

Vets, Manufacturing Industry, Welders (welding suppliers), Aerosol manufacturers, Hospitals, Dentists, Breweries and dozens of others all use Nitrous Oxide for various things. Ask them if they will supply you as well? Its often the cheapest option.

Or ask them where they get their Nitrous Oxide locally?

This is often the best way to find out.  I used to buy my Nitrous Oxide gas at very favourable rates in 100lb cylinders from Kingston Medical Gasses in Hull in the UK but they have now disappeared unfortunately! There's always plenty of places advertising online if you get stuck. But its likely you also have someone in your hometown that offers a refill service like a tuning shop and its quicker.  Don't worry there are more options.

It is also possible to buy Luxfer cylinders complete with VTI Diptube valves at reasonable rates from www.nitrousoxidesupplies.co.uk as well as Nitrous delivered.

You can rent a large refill cylinder from your local branch of Lynde Gas, Contact the Head office 0121 500 1000 for your local supplier. There is another large UK supplier but the name eludes me at the moment! (This is UK only of course, you well need to find your own supplier in other countries)

Then you can refill your own bike/car at home as needed. This is the best way, if not quite the cheapest.

You can also try your local branch of "Air Products" or "B.O.C." but don't tell them it is for automotive use because they seem to have a completely irrational fear of using it for this purpose!  Depends who you speak to and how you put it... And remember it has a bad rep for other reasons too! (some people "sniff" the stuff to get high).

Or you can try THIS guy, he will deliver, pick up, and supply your gas in the UK.  Read HERE for full info.

Refilling your own bottles from a large rented one at home

So you have sorted out a supplier of refills or somewhere to get your small car/bike bottle filled? That OK then! 

But if like me you find it inconvenient to keep getting your bottle filled, or cheaper to buy bigger quantities then you will need to fill your own!  Find someone such as Linde (Above) to "rent" you a huge "fill" bottle (100lb or above) that they will collect / deliver to and from your home. Then you can fill your smaller bottles from this.

My bike's) had a small 2 1/2lb polished alloy bottle, and my Cars had 15lb bottles. These were refilled sometimes every evening (I am addicted!) especially on bikes!

I didn't rent a big bottle as most people do, but used an old Argon bottle (I think) 100lb+ that was found at the back of my mates workshop!  This is rated at much higher pressure than needed for Nitrous, so safe. Kingston Medical Gasses (now closed down sadly!) used to fill this for me when I needed it very cheaply!

All you need to fill your own bottles is:

• Something to accurately weigh the empty and full bottles.
• A fill loop (a bit of pipe to connect the full bottle to the empty one) - this can be cheap 4mm Nylon, with some simple end fittings.
• A spanner
• A brain...
• You do NOT need a pump!

1. Check out the big bottle you are filling from. Does it have a siphon tube inside of it? Most do not.  You need liquid Nitrous so you may need it upside down or at least angled down by 15 degrees.  Bottles or Cylinders with siphon tube generally have a white painted line on the side to show this.

If it has a siphon tube leave it somewhere on the floor or preferably higher up and upright! With the valve at the top. If it's higher up than the bottle to be filled it will flow more easily into it. Nitrous flows from warm to cold, and from higher to lower! Remember that its important!

Remember you want the LIQUID out of it not the gas so if like most bottles it DOES NOT have a siphon tube, this fill bottle MUST be upside down!  It does not need to be completely upside down, but the valve will need to be a little lower than the "bottom" of the bottle. Maybe 15 Degrees is enough. However you organise this, it must allow the LIQUID Nitrous to come out not the Gaseous Nitrous.

2. Connect a pipe (small bore nylon 4mm O/D, bit of braided hose, or whatever you like that can take the 1000 psi that will be in it! that is 1 to 2 meters long to the valve. Ready to connect up to the bottle you intend to fill up - but don't connect this yet!

3. Take the EMPTY bottle you need to refill and weigh it!  Write it down.  Learn it, and in any case it should be stamped on the bottle... But you MUST KNOW IT!  Don't get it wrong!

4. Now stick it in your deep freeze! Preferably the night before. Seriously. You need the bottle you are filling up to be colder than your big fill bottle is. Because you need LIQUID Nitrous!  Since they will be connected together, the pressure in both will be almost the same.

The bottle to be filled will be lower down physically, (on the floor?) so its pressure will be slightly higher when the valves are opened. The pressure and temperature difference will ensure that your bottle will fill properly with liquid when you open the two valves. If its not cold enough filling will stop or really slow down. Use your scales or weighing device to see this.

5. Take you ice cold bottle out of the freezer, and connect it up to the big fill bottle that's waiting!  Lay it on your "Bathroom Scales", or Spring Balance so you can see the weight... 

6. On the bottle will be stamped the "full" weight, or the amount it holds... Open the valves, you will hear the Nitrous rushing in. When the CORRECT amount of Nitrous has filled your once empty bottle STOP!  And disconnect.

DO NOT OVERFILL!
Its actually very easy to get say, 3lb in a 2.5lb bottle or 18lb into a 14lb bottle, but its not big and its not clever!  The extra space is DESIGNED to be there!  Its expansion space and its important!  

You don't want to see what happens if a blow off / overpressure valve fails to work...
Your house will be no more...  You will be no more!

If the bottle stops filling before you get your 2.25 Lb in it then turn off valves. Disconnect the small bottle. Vent vapour to atmosphere until the bottle is ice cold!  Not liquid! Vent gas only.

It will get to extremely cold doing this as the liquid inside tries to turn to vapour. Very quickly. You may lose 10 percent of the contents doing this though. But it works and its faster than the freezer. Reconnect and continue filling.

*Technically the term NOS is incorrect as this refers to an specific company (called Nitrous Oxide Systems, in the US)