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MikeSD · Member

I posted a thread about filling from a scuba tank. I think I got what I needed in that thread but have some general questions about high pressure.

1) What is the best procedure for filling your gun to a known point?

I suppose one could just get an expensive guage and use it at the tank. But I'm equally sure that most don't go to that bother. I also suspect one could just fill to the maximum, chrono every shot, and mark the guage, where you got the best results, and then fill to that point from then on. But you wouldn't then know the real pressure.

2) All guns say to fill to a certain pressure. But if these guages aren't very accurate, how do you comply with the requirement to fill to a specific pressure?

3) Is the pressure the same, in all parts of the system?

On the face of it it might seem like "duh!". I mean, once everything is stabilized, I would expect all guages on a volume would measure the same reading, if they were all accurate (i.e. calibrated). But during the fill process, even with calibrated guages, would the pressure be the same, during the fill process? I suspect it might be higher on one guage than another, at least during the fill process. Is that a true statement?

3) What mechanism is there for setting a maximum air pressure on a pistol (i.e the Marauder)? Is it just a safety factor rule that says don't fill beyond? Is it a pressure release valve that prevents overpressure? What actually prevents over filling?

4) I have seen comments about tuning a pistol to work at a higher fill pressure. Is that even possible? I know you can tune them to perform at their peak performance point but can you actually make them take more pressure, within the mechanical limits of the gun, that is. Obviously if the seals leak at a specific point, you'd have to change the seals. But with regards to any mechanical adjustments on a gun can they be tuned to increase the pressure?

The reason I ask this question is because, like I mentioned in my other thread, my pistol only shows 2800 psi. I don't know which of my guages might be off. Assuming the pistol was actually reading 2800 psi and that was the actual pressure, is it possible that any adjustment would be making it limit at 2800 psi?

SMP · Silver Status Member

1) A regulator with an accurate gauge is the most accurate way to fill any pressure vessel. Connect tank to regulator to fill hose to gun. Turn the regulator down to it's lowest setting. Crack open the tank and gradually turn up the regulator until the gauge shows the pressure you require. Lock the regulator at this point. You wouldn't want to know what a regulator of this rating would be worth.

There is usually two output ports on a good regulator. One would normally have a burst disc safety install in it

2)I assume they are not concerned with +/- 5%

3) within seconds the pressure will equalize on any system not having a very tight constriction some where. When I have 200bar on the main tanks in a ship they will have 200 bar in the anchor pocket 400 or 500 feet away. For realistic purposes you can assume that pressure differential waves will travel at Mach.

3.1) Yes it's a safety factor of 3/5. There is no mechanical device that would prevent overfilling inside the gun

4) yes it's possible to overfill anything if your determined enough to put a concerted effort into killing yourself. Realistically I see no advantage performance wise to exceed the 3000psi working pressure. At that pressure the gun already has more untapped resource than you could realize given the other restraints such as valve potential

MikeSD · Member

SMP · Silver Status Member

WhitleyStu · Veteran Member

I think most of your questions have been answered thoroughly, but it needs to be stated that you do need a good gauge(s) in your fill system. I've worked around 10,000 psi systems and have a great respect for anything and everything under pressure. I opted for two liquid filled gauges on my tank valve; one of the tank side of the valve and the other on the line out side. Know the proper working pressures of your equipment and have accurate control of it. Exclamation

MikeSD · Member