DIY Nitrogen Tank and Refill Kit

Maybe I missed it, but I have yet to find a decent thread on this site discussing how make your own nitrogen refill kit. Here is how I went about it.

1. Get a 20 or 40 cu. ft. nitrogen tank - Size of tank depends on whether you are planning to use it for personal use to keep shocks at proper pressure and rebuilds (20 cf tank), or want to also help out your friends to do the same (40 cf tank). You can buy these online, or buy the tank with the nitrogen in it from a welding supply store. It is my understanding (possibly wrong) that if you buy an empty tank, you run the risk of the gas re-filler refusing to fill the tank without it being inspected first. You might also have to wait a few weeks to get the tank filled. As such, it might we worth the cost to just buy a tank (generally pre-used, usually empty tanks get turned in for filled tanks) with the nitrogen in it.

2. Get a nitrogen regulator that has a rated working pressure of at least 400 psi. While most shocks run at 150 to 250 psi, if you are going to rebuild, you want to be able to set the pressure higher (350 to 400 psi) for at least 24 hours after a rebuild to check for leaks. Don't cheap out here and get the cheapest option off Amazon, as you will just end up spending more money in the long run (see below on discussion of a fill tool), and a cheap regulator might not be able to function to its supposedly rated working pressure or fail early. I got the following from my welding supply store. It seems like a good bang for the buck, considering you can spend over $300 on a regulator. MD Nitrogen regulator, 0-450 PSIG | MillerWelds

3. Get a air hose. The hose needs to be rated for a working pressure up to 400 psi. As such, you can't safely use standard air hose. Furthermore, most nitrogen regulators (including the one listed above) have an output that is a male 1/4" flare connection (most air hoses interface with 1/4" NPT). These regulators are meant to be used with A/C charge hoses, which are rated well above 400 psi. I ended up getting the following off Amazon

$30 Yellow Jacket 21060 Plus II Hose Standard 1/4" Flare Fittings, 60", Yellow

Yellow Jacket 21060 Plus II Hose Standard 1/4" Flare Fittings, 60", Yellow: Industrial Hvac Components: Amazon.com: Industrial & Scientific

4. Get an air chuck that will interface with a female 1/4" flare connection. I got an air chuck from TSC with a female 1/4" NPT thread, and then bought the following off Amazon to convert from 1/4" NPT to 1/4" Flare

$6 JUWO 1/4" Flare x 1/4" NPT Male Reducer Adapter, Brass Gas Fitting for Natural Gas, Propane, Fuel, Half-Union (1-Pack)

Amazon.com: JUWO 1/4" Flare x 1/4" NPT Male Reducer Adapter, Brass Gas Fitting for Natural Gas, Propane, Fuel, Half-Union (1-Pack)

Side Note: You might be able to locally source Items 3 and 4 at a HVAC supply store and/or propane supply store for cheaper.

5. (Optional) Get a fill tool. This is basically a tool that attached to your shock with a no loss air chuck, has a pressure gauge, possibly a bleed valve, and a connection for your air hose (might be a schrader valve or flare fitting). This YT video shows a King version How to fill shocks with nitrogen. (youtube.com). If you buy a quality regulator, you really don't need the fill tool to check pressure. You can set the pressure at the regulator and just use an air chuck to top off or refill. From what I have seen, a quality regulator should be get you within 5 to 10 psi of where you need to be, which is plenty accurate for our purposes. Given that these tools cannot tell you what the pressure is in a shock, without reducing the pressure in the process of trying to measure it, and that the bleed valves can end up being too coarse to reduce pressure accurately, I don't really see the need for them. If you want to reduce pressure, just bleed the shock and then refill to the pressure you want using the regulator.

Below is a picture of the 20 cu. ft. setup I have currently. All done and said, I put about $300 into this, with the most expensive item being the regulator. Just rebuilding your shocks on your own once, will more than pay for the cost of this. To have the capability to immediately modify or maintain your shocks from the comfort of your home...priceless.

 

Gonna grab a no loss fill valve and flare adapter then see if I have any HVAC friends that can give me a fill.

 

solid post.