Low pressure/small capacity shots per fill...

[DavidBoren]

I know that you can get about 150 shots from your typical 13/3000 tank with a ~750psi output pressure.

But what about if you have a 450psi output pressure on the same 13/3000 tank?

How about 450psi on a 22/3000 tank?

[coyote]

Depends on the valve train you are feeding. Nelson valves and automags will starve much sooner than markers with lower operating pressures.

[DavidBoren]

How about a ~300psi STBB or 'cocker?

[Jordan]

Where'd you get the 150 shot count from?

[Memornix]

Sounds like this is a question of Boyles law. If you decrease the pressure by half you will require half the gas to fill the same volume. The problem here is that it doesn't translate well to feet per second. If you cut the pressure in half in a marker and kept the same volume per shot you wouldn't get the velocity required so it is really a balancing act to find the sweet spot for your particular setup.

In short, less pressure would require more volume per shot to get the same fps. The only real way to know is the sweet spot the marker and see what you get.

[grendal50]

I think it depends on what the paintball gun requires per shot. A regged Spyder using 300 psi isn't going to use any more air if the tank outputs 850 psi or 500 psi

[jerryjjackson69]

There have been lots of tests regarding the claims of low-pressure tank outputs gaining more efficiency on markers. It really comes down to the marker and when that marker and all the regulators in the system start to experience drop off. A lot of the older systems would start to have issues when the tank output dropped below 700-500 PSI even if the marker was operating at 200 PSI, so setting your tank to 400 PSI and chronographing the marker with that input pressure would mean you could get more shots out of that setup before experiencing drop off at the end of the tank. Most of the modern regulators on both tanks and markers as well as modern bolt systems do a much better job of just working until the air runs out, but some require or recommend a lower pressure to prevent seals from blowing out or to just make the marker feel or sound better when shooting.

If your nelson only chronos with 850 PSI, then you start to get hosed when your tank drops below that, but if you can make adjustments and reach velocity at 500 PSI, then you get more shots before your tank runs low (as long as you're not just using a bunch more air per shot to get that velocity). This is a simplified example ignoring additional regulators on the marker, which may have differences in output pressure when input pressure changes.

An example from the other end of the spectrum: We took an Emek and tested how many shots it got on a cold fill 13/3k tank several times (this initially started as a test to see how "consistent and repeatable" efficiency was), and we had 177,175,176, and 179 shots. It was easy enough to drop the output pressure of that tank from 800 PSI down to 350 PSI and run the test three more times, and the numbers were 172, 174, 175. Basically the same numbers, definitely no increase. The test was done by setting the velocity to ~285 before all the tests with no adjustment in between, filling that tank until the regulated 3k station stopped, then letting it cool and repeating the fill twice, at which point even when cooled the tank would not open from the fill station input to accept any more air, counting out 200 paintballs using 10 rd tubes, then shooting until drop off appeared. After shooting until drop off appeared, we then got the chronograph back out and fired one ball at a time until two consecutive balls were below 250 FPS, then counted the remaining paintballs to figure out exactly how many were shot. (This was much easier when we tested markers with shot counters, but we never ran the test with different output tank pressures on the high-end markers). It wasn't a perfectly controlled test in terms of paint, exact fill pressure, etc, but it does prove that lower pressure tank output doesn't always get better efficiency like many companies and online paintball gurus claim and that markers do have repeatable results in terms of efficency. We have the same results in terms of repeatable efficiency on a geo3.5, LV1.1, CSR, NT11, Clone VX, an autococker, and M2. I wish I still had easy access to where I had the resources to run these tests, it was a lot of fun and you could ballpark a marker being more or less efficient than another one, but it wasn't perfect with the tests being months apart with different batches of paint, different chronographs, etc. And the Emek was the only marker we tested on different tank output pressures.

More fun: A marker that gets 175 shots on a 13/3k will consistently get 650 shots on a 48/3k. We didn't get the chance to get a 68/4500 number to compare that too, as the shop air didn't go past 4100, but since the numbers are repeatable you can run the test with a 13/3k and a 68/45, do the math, then test all your markers on a 13/3k and run the math again to get an accurate efficiency number for any marker on a 68/4500 without having to get a good 4500 fill, waste all the paint, etc. It could become the standard efficiency test instead of everyone having a different size 4500 tank with a random fill pressure getting different numbers in every video. All you need is 3k air.

TL;DR - Dropping your tank output pressure won't automatically increase the number of shots you get. It can in certain circumstances, but not in the way that marketing and self-proclaimed master techs want you to believe.

[DavidBoren]

Wow. Thank you.

[MrKittyCatMeowFace]

Thank you for the very clear info

[DavidBoren]

I should have clarified exactly what it was that I am interested in.

I was under the impression that you could use more of the tank with a low pressure system... the lower output pressure on the tank regulator allowing you to "drink" deeper into the tank. I am not exactly sure how I came to this conclusion, but I figured I'd ask the experts to either confirm or crush the theory.

The ~150 shots per fill is from my own experience with 13/3000 tanks on the various STBB markers I have ran them on. I generally use 50-150(ish) capacity hoppers, so I don't have an exact count, but judging by the number of balls left or how many reloads I got... yeah, about 150...? All this was with the standard ~750psi output from the tank.

I have been using a VS3 balance valve, an Evil valve, and there might have been a 32* Magnaport valve in use for a while. It's all been regulated (Evil Detonator or ANS GenX). Not exactly sure what the final regulated input pressure to the markers was but it was hitting velocity easy enough with relatively light springs. The GenX was reading around 300psi when I had the VS3 balance valve in the Vexor, and I didn't mess with it to try get it any lower... didn't honestly trust the GenX to go any lower, either.

Anyways, I was hoping to milk a few extra shots from my little 13/3000 tanks by dropping the output pressure. If that's not the case, oh well, it's not going to ruin my day either way.

[Seajay]

...

Anyways, I was hoping to milk a few extra shots from my little 13/3000 tanks by dropping the output pressure. If that's not the case, oh well, it's not going to ruin my day either way.

Yes... usually. If the marker is reasonably efficient then by dropping the operating pressure you would be able to get more out of the tank. Dropping the Tank reg pressure further down would also allow you to "drink deeper into the tank" so to speak. Or the other way to think about it still have shots at velocity (drop off point).

The air volume needed to still hit velocity, and cycle the marker for some, does have an impact and you tend to use more volume at lower pressures, however if the marker is reasonably efficient the extra volume shouldn't matter. A marker that wastes a lot of air to function vs one that does not will have a pretty big impact the lower pressure you go because dwell times tend to increase.

The Balance valve you should easily be able to lower the Tank reg to 500/550 PSI and shoot normally. That alone would let you get some more shots off because the balance valve is 200-300 psi valve.

I've got a 500 Ninja Tank that powers my balance valve marker at 200psi just fine. Switching to my 800 Ninja or my 900psi FS 13ci doesn't change the velocity or reg pressure (Palmers female stab).

[jerryjjackson69]

The concept of "drinking deeper into the tank" is correct, but it only works if your marker stops functioning correctly when your tank output gets low. Some markers have problems when the input pressure drops, so you build them around LP input then get more shots on an LP tank. But if you have a marker that shoots the same on HP or LP input, and just shoots until you run out of air as opposed to having problems when your tank output drops off, then lowering the input pressure won't by default gain more shots. Typically a quality HPR on your marker will have a minimal variance in output as input changes or drops, same for your tank regulator, so everything should shoot until the air runs dry.

Assuming volume and mechanical dwell is the same for your different valves (its probably not, but it is for the sake of example), then whichever valve chronographs correctly at the lowest pressure will let you continue to shoot more as your tank runs low and pressure drops (because the pressure will still be above what the valve needs).

My 220 PSI pump gun is an air hog, really inefficient, but it will still shoot at velocity when my tank has 300 PSI left in it, as long as my regulators haven't started leaking with such a low pressure not sealing the o-rings correctly.

[DavidBoren]

In the case of my STBB, it will shoot with 0psi in the tank... one of the many wonders of a mechanical marker. But that's just me being difficult.

Say that a STBB marker is sprung and sweetspotted to 300psi at the HPR. It's slinging at 290fps. 100% reliable operation.

Does dropping the tank regulator from 750psi to 450psi allow this example to drink further into the tank?

Lowering the tank regulator any lower than 450psi and the variance between the tank and the HPR is too low for the HPR to accurately do its job... that's why I chose 450psi for the 300psi example.

I don't think the marker gives half a crap about the air on the other side of the HPR, honestly, but it will be interesting if the air in the tank cares about the efficiency of the marker.

How do either ever "see" the other through the HPR?

Doesn't the HPR translate both ways...? The marker only "sees" what the HPR shows it, and the tank only "sees" the efficiency of the HPR.

[jerryjjackson69]

With your given example, that change in output pressure would not typically allow for any additional shots, unless your tank regulator or marker regulator either start do have drop off when their input pressure drops. Every regulator will have a drop in output pressure as input pressure drops, but it is usually not noticeable until you are so low on air that everything stops anyway. The HPR doesn't "see" whats in the tank, it only "sees" what the tank reg puts out, (which is 750 or 450 PSI depending on which example) until the tank pressure drops below that, then it "sees" whatever air is left until it runs out. Does your HPR act differently with 750 or 450 PSI coming into it? If not, then you probably won't see any change in efficiency with that example, which is pretty standard for most setups or examples these days.