The most common 20 oz CO2 tank sits at room temp with 800-850 psi. Most gauges that size are too small to get any decent level. And CO2 tanks show that same psi gaugeadingull down to a couple of ounces before it starts to drop. CO2 is measured by weight.
Nitrogen, or HPA (High Pressure Air) comes in 3000 & 4500 psi steel/aluminum and carbon fiber. 3000 psi tanks are almost exclusively steel. 4500 psi tanks are carbon fiber wrapped with aluminum bladders. HPA is measured in volume. Common tank sizes are 45, 48, 68, 70, and 88 cubic inches. HPA needs a step down reg.
This info is based on paintball use.
Hard to see how that regulator would fit on a 5 lb tank. The 5 takes the same connector that the 50 lb cylinders.
Nikon Pimp #084
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