HP vs. LP : efficiency

[dinger]

my local pro shop has told me that when my bko is running at 90psi, it will actually use up more air than if my gun was working at 700 psi.

his facts of backing this up was that even though the gun takes less pressure, it will still need the same amount of volume, if not more, to shoot the ball at 280fps rather than using more pressure

not much of that made sense to me though... and it is contrary to what i thought. i thought that lp would actually use less air due to a lower pressure needed, but im not too sure.


the point of topic:
does running a gun at lp really use up more air [or volume] than running a gun at hp?

or is it all a lie?!

[nippinout]

Take two 12grams of CO2. Pop open one of them and let the gas expand a balloon. Compare the balloon and the pressureized 12gram. They both contain the same amount of air. The difference is the volume and pressure.

The 90psi gun will use a larger volume of air, but that will be at a much lower pressure than the 700psi air. The same amount of energy, however, will be used.

[dinger]

so would that mean operating at a lower pressure actually uses up more air than operating at a higher pressure?

[nippinout]

A)1 cubic inch of air at 1000psi = 1000 in-lb of energy

B)10 cubic inch of air at 100psi = 1000 in-lb of energy

Example B uses more volume of air than A. But you must remember that B is an expanded volume of air.

Both have the same exact potential energy to propel a paintball. Both have the same amount of molecules of air.

[dinger]

ah ha i see

so that means what my shop said isn't exactly true. b/c he said that lp guns would actually use up MORE air than a gun running at a higher pressure.


time to show him up with the intelligence of AO

[Xyxyll]

On some markers (the Spyder for example), the efficiency of low pressure goes down once you hit a certain point. It is almost like a bell curve. Going down from 800psi stock, it goes up and up and then starts going down. What is important is finding that ideal pressure. One day (well, would probably take more than a day) I'll sit down and draw out my own bell curve. I'll probably need a compressor for all that air and consistancy of fill that I'd be dryfiring (emptying a tank per set pressure).

[athomas]

All guns use low pressure behind the ball. Its the ability of the gun to deliver any available air to the ball that makes the difference whether a gun is efficient or not. Higher pressure allows increased flow even if there are flow restrictions. This maintains efficiency. A gun that uses low pressure may also have good efficiency if it can deliver a high volume of air to the ball in a timely manor the same as a high pressure gun.

[AzrealDarkmoonZ]

LP and HP are largely irrelavent when dealing with most poppet valve markers. The dwell and flow are the two largest increasers to efficiency.

Az

[ezrunner]

AZ is getting there

Every gun / valve combination has a flow path.

The flow path is the path the air must take to reach the ball.

It takes a certain amount of force to expell a ball from your marker at 300 fps.

For every flow path there is one optimum efficieny setting, and several that are close.

You can open the valve for a short time with a high pressure or a long time with a low pressure, depending on your flow path you will have better efficiency with one choice than the other.

The Mag uses a chamber of air regulated to about 450 psi to 550 psi depending if you have level 10 or not and what configuration you have for power tube spacers, orings, etc

This air is routed down the power tube , around and through a bolt, then to the ball. The air is about 90psi when it hits the ball, due to the path the air travelled to get there.

The MacDev Sonic Valve in a bushmaster from ICD runs best at about 165 psi. The air runs in a line straight up, then turns and through an open face bolt hits the ball.

Same effect, a blast of 60 - 90 psi hits the ball and pushes it out the barrel.

The best effieciency is when you open the valve and get the required volume through without any excess. For the BKO to run at 90 psi they have to hold that valve open until the ball has started moving and is well into the acceleration. At 160 psi the valve can shut much earlier and the air volume in that space will push the ball out and expand to do the same job, with less total volume than the 90psi setup.

The lower pressure is not necessarily "easier" on paint. A lot of that has to do with feeders, timing, and LPR pressure as that affects bolt speed.

Bolt speed and shape of the bolt face can dramatically affect the handling of paint in your marker as your bolt can damage the next ball in the stack as it slides past to load the current ball.

There is a best setting for each gun, then several other good settings. Find a good setting that does what you want. My advice is the lowest setting that gets you to the efficiency range you want. That way your lpr is low, your bolt is travelling nice and slow so it isn't abusing paint, and the recoil of the gun is lower.

The level10 in the mag works great because the bolt is slow going forward when you can damage paint, and fast going back where you aren't going to hurt anything.

-rob