Just how do regulators work anyway?

In today’s high-tech world of paintball, almost all of us use a pressure regulator of one kind or another. One of the first in the industry was, of course, the AIR valve in the Automag, introduced almost a decade ago. Now, we have multi-stage “pressure balanced” HP nitrogen systems, inline regulators, more paintguns have regs as part of the operating system... the list is endless.

So how do they work?

First off, in the very basic design, the pressure regulator is essentially a spring-loaded check valve. Fig. 1 shows a simple, basic regulator. This design is used, in one shape or another, in the Automag line, Air America’s HPA systems such as the Raptor and Apocalypse, and even the ANS ‘JackHammer’ pneumatics reg for the Autococker, among several other applications.

Fig. 2 shows an RG-1 type reg design. The concepts are essentially the same, but for simplicity's sake, the majority of this article will be in reference to the fig. 1 system.

In this example, lets start with the ‘adjuster’ backed off, so there is no tension on the ‘reg piston’. What is happening here is, the high pressure (supply) air is pushing the ‘reg seat’ against the ‘seal’. This seals the HP air from escaping, and probably getting into trouble somewhere.
This seal is made, because the ‘supply’ air is at a higher pressure than the ‘output’ air, which keeps the seal shut. So now, we crank down on the ‘adjuster’, which begins to put mechanical pressure on the ‘reg seat’. However, the ‘supply’ pressure is still greater than the spring pressure against the ‘seat’, so it remains closed.
But if we keep cranking down on the spring, eventually the spring tension will overcome the ‘supply’ pressure, and force the seal open. So now, air is allowed to flow between the ‘seat’ and the ‘seal’, and begins to fill up (pressurize) the ‘downstream’ side of the reg. (Toward the gun, assuming nothing leaks.) At a certain point, because the ‘reg piston’ is in a sealed area on the ‘low’ pressure side of the reg, the additional pressure in the downstream side also begins to push on the reg piston, helping the supply air pressure force the reg seat closed.

This is the tricky part. Assume the ‘supply’ air is X psi. Assume the output (or downstream) side rests at less-then-X psi. Once you start cranking down on the ‘adjuster’, the spring pressure on the ‘reg piston’ gradually forces the ‘seat’ open, allowing the ‘supply’ pressure to flow to the ‘output’ side. This begins to pressurize the output side, which in turn begins to push against the ‘reg piston’ against the force of the spring. At some point, the supply pressure against the ‘reg seat’ and the pressure against the ‘reg piston’ from the output side overcome the spring’s pressure and force the seat closed again. At this point, everything is in a state of balance.

Now, do something stupid like fire the paintgun or crank down on the adjuster harder, and things happen all over again.

When you fire the paintgun, that reduces the pressure in the ‘output’ side of the reg, so that the spring tension can again force the ‘reg seat’ open. This allows a small burst of air back into the output side, and as soon as pressures equalize again, the reg seat closes. (This is known as "recovery" and faster recovery is better, to prevent velocity drop during rapid fire.)

Or, in the other example, you crank down on the adjuster, which adds spring pressure which forces open the ‘reg seat’ again. And again, the seal allows a small volume of air through, and as soon as pressures equalize again (This time at a higher pressure) the ‘reg seat’ closes again.

The action of the reg seat opening a fraction of an inch and repressurizing the output side happens each and every time you fire the paintgun or alter the velocity. The reg could also be having to constantly work very slightly if your system leaks, as it tries to maintain downstream pressure.

Now, this is a very simple, basic description of how a regulator works. There are a lot of other factors to consider, such as how the loss of the ‘supply’ side pressure can increase the output pressure. Once the tank pressure drops, it becomes easier for the spring to push the seat open,and
that’s the equivalent to increasing the spring pressure, so the output pressure rises, even though the adjustment is unchanged. Also, as most ‘Mag owners will testify, the condition of the reg seal can become critical; if the seal/seat leaks, there is nothing to stop the full tank pressure from passing through to the rest of the gun. A dangerous situation in some cases. (That’s why HPA systems have burst discs on the output side.)


There are quite a few different designs of regs in Paintball, though most can be classified as one of two types: The most common type has the adjuster vary the tension on a spring, which acts on a reg piston and seat, against a fixed reg seal. This design is used in UniRegs and Automags, among others.
The other design has the adjuster press directly against the reg piston and movable reg seal, which acts against a “fixed” spring pack. This is the basic design of the RG-1, Angel foregrip reg and WGP reg.

There is, of course, far more to pressure regulator technology than this little article can hope to cover. But the basics are here, and hopefully, this will help you to better understand the inner workings of most regulators.