So you know what the pressure going through your marker is by reading the gauge on your reg or VA but really don't know what the actual output pressure of your tank is? You've read that it's supposed to be this or that but how do you know for sure? Let's make a simple tool that'll give you a relative idea of how much output pressure is really being exerted from that tank.
Different Types Of Propellant Tanks
There are a few different types of propellant tanks you can choose from to run your paintball marker with. I'd venture to say that C02 being the most widely used and compressed air or nitrogen a close second. A C02 tank has an unregulated output pressure while N2 or CA have integral regulators built into them that can either be adjustable or regulate to a specific output pressure, or so it seems. This is why the cost factor of N2 tanks are much more than C02 tanks. All N2 tanks have a gauge installed on them but this gauge shows the internal pressure, not the output pressure of the tank. You can fill an N2/CA tank with C02 but cannot fill a C02 tank with N2/CA. Nitrogen(sometimes the name confused with nitrous or nitrous oxide) and compressed air can both be filled into the same type of bottle or tank. All a bit confusing?
Here's more:
C02 tanks are composed of either aluminum or steel. The most common C02 tank capacities are anywhere from 3.5oz to 20oz. There are disposable 12 gram C02 cartridges used in stock play paintball as well. The capacity of a C02 fill is measured by weight. For more information about filling with C02, see 'Making a C02 fill adapter' in the SPPS tech section.
N2 tanks are made either of steel or fiber wrapped aluminum and are normally a bit heavier and carry more bulk than C02 tanks. Their size designated by cubic inches and pressure capacity. These tanks most commonly run anywhere from a 47 cubic inch 3000psi(47/3000) to a whopping 114 cubic inch 4500 psi(114/4500). The capacity of an N2 fill is measured in pounds per square inch(PSI) which is noted on the gauge that is attached to them.
Shot Count
There is a relative formula for calculating how many shots you should get from any of these tanks but I will not bother to feed you that information because it really depends on what type of marker you're shooting. You cannot compare the shot count that you will acquire from a Tippmann 98 Custom which is normally a gas hog compared to a Phantom pump which is very conservative on propellant consumption. We could even base this on the same marker: you could take an Impulse right from the box and get just under 1000 shots from a 68/4500 N2 tank but if you added an LPR, some new internals and valve, you might get twice the shot count afterwards. I haven't even thrown in the tuning factor but I suppose you get my point. Another factor is that when using C02, the bottle will yield more shots on a hot day than a cold day because C02 expands and contracts depending on the atmospheric environment it's being utilized in. This is one reason that C02 is labeled, 'the unstable gas'. There are so many variables, let's just leave shot count as an individual marker and source determination rather than a general formulated estimate.
Making The Pressure Test Gauge Tool
Never thought I'd get to the core of this article did you? The parts you'll need to make this test tool may be laying around in your spare parts box. If not, they can be purchased used or new for a relatively modest cost. You'll need a bottom line air supply adapter(BL ASA), 0 - 1200psi or 0 - 1500psi pressure gauge, teflon tape, a small piece of wood, plastic stock or metal stock and a couple of wood or machine screws. A BL ASA with an on/off is ideal for this tool because you'll have the option of shutting off the supply of pressure or purge the excess pressure in the BL ASA before screwing the tank to and from the test tool. The tools you'll need would be a wrench to tighten the gauge down, a screwdriver, a drill and a tap for the machine screws if you choose metal stock as the material for the testing tool hand brace.
I will be using a BL ASA from a Tippmann 98 Custom for the main tool body and a piece of Tik wood for the hand brace on mine. Cut and shape the small piece of wood, plastic stock or metal stock to fit flush against the BL ASA. The measurements and shape are up to you. It will be used as a brace for your hand when turning the bottle onto and off the testing tool. This article is just a guide, so your testing tool may differ from the one shown here. Some decisions like design, parts and measurements will be of your own choice.
Now that you have shaped the hand brace material, you'll need to drill 2 holes in it to attach the hand brace to the BL ASA with the 2 screws. You need to use the correct size drill bit for the screws. If they are too small for a wood piece for instance, it may crack the wood when you turn the screws in. There is a proper hole size needed when tapping holes in metal as well, so you'll need to research that information prior if you use metal stock. Plastic is pretty flexible, so using the correct hole size isn't so detrimental but a good idea anyways. Just be careful not to drill the hole too large for any material that you use. Be sure the screws are long enough to withstand the torque exerted when screwing the bottle on especially when using wood. If the screws are too short, there's a chance they may strip and break the hand brace from the BL ASA. Once you have completed this part of the task, screw the 2 pieces together.
The only thing left to do now is screw the gauge into the BL ASA and you're done. Most pressure related accessories pertaining to paintball have a 1/8" NPT thread size including the pressure gauges. Spyder markers on the other hand use a metric thread size. If you try to screw an inch thread gauge into a BL ASA with metric threads, the threads will mismatch and therefore not mesh together. Check all of this before starting your project to be sure everything fits together properly. Wrap a few layers of teflon tape around the threads of the gauge in the opposite direction that you will screw it into the BL ASA. There are 2 types of teflon tape, white and yellow. Yellow is a bit thicker and easier to work with than the white. Leave 1 or 2 threads bare at the end of the gauge so the tape doesn't fray. A piece could inadvertently block the inlet hole of the gauge. Screw the gauge into the threaded hole that you would normally screw the pressure line into. You don't need to torque the gauge down extremely tight, just enough for it to seal well into the BL ASA. The tape will take care of any possible leaks. I simply hand tightened mine and it sealed just fine. Voila........you're done!!!
Using The Test Gauge Tool
Using this test tool is quite simple; twist the tool on your tank and the gauge will show the output pressure of the tank. These gauges we use in paintball aren't entirely accurate. That's why they are so modestly priced. A fairly accurate pressure gauge might cost you an excess of $50 or more. The small inexpensive gauges we use for paintball will suffice for our purposes though. Unless the o-ring on your tank is bad and leaks, there should be no pressure released while turning the tool on the bottle. You might think about putting a small bit of oil or better yet, a little Dow33 on the tank o-ring and inside the ASA before turning it on. This will aid with installing and removing the tool. If the BL ASA you are using does not have a purge or on/off, it will spew a small poof of pressure when turning the tank from the test tool. The hand brace is attached to give your hand a little leverage when turning the tank on and off. It will help you do this a bit more quickly otherwise the BL ASA may have a tendency to just slip in your hand.
Fixed regulated N2 tanks are available in either low pressure or high pressure output configurations. Low pressure should have a relative output pressure of 400psi. High pressure should be relatively 800psi. C02 tanks on the other hand may range between 400psi on an extremely cold day to 1200psi on a hot day. When testing my tanks; the HP 68/4500 N2 tank had an output of just above 800psi. The 3.5, 14 and 16oz tanks all had a consistent output pressure of 1000psi. This was all in a relatively 75* environment. I left the 14oz in the freezer for about an hour and the output pressure was just below 400psi. A 600psi variation in pressure output between 75* and 32*.
All the different types of tanks available come equipped with a safety burst disk in case pressures become exceedingly high. The excessive pressure simply breaks through the small copper disk and purges the pressure through a small removable orifice attached to the tank. This would be more prone to happen with the unstable nature of C02 than nitrogen. This is why it's not a good idea to leave a C02 tank in direct sunlight or in a hot enclosed area. If you play paintball continually for a while, you will most likely experience this outburst of excess pressure at one time or another. Not a real danger but quite shocking to say the least.
Technical Information
