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Number of Pressure Chambers
Posted: Sat Apr 04, 2015 1:22 pm
by SEAL
I got this idea from a conversation on Facebook. I think most of us would agree that two (or more) air pressure PCs are better than one. After all, aside from maybe the XP 105, most dual-chamber guns outperform singles. However someone said that one large chamber would work just as well. Does anybody know if that's true? I feel like more than one PC would give you higher pressure with the same amount of water. I may be studying engineering, but that don't mean I'm good at it, so maybe someone smarter like Ben could provide some insights on the benefits of multiple chambers vs. only one. At the very least, it could make for a good discussion.
Re: Number of Pressure Chambers
Posted: Sat Apr 04, 2015 2:47 pm
by HBWW
From Ben's past posts, I'm pretty sure it was a matter of surface area of the amount of water exposed to the air. Adding a 2nd chamber that's identical will double that surface area, improving the performance. Of course, the pressure will be lost more quickly as well.
There's probably a practical limit somewhere, but I'm not sure where that is.
Re: Number of Pressure Chambers
Posted: Sat Apr 04, 2015 3:09 pm
by the oncoming storm
From a logical standpoint if total chamber volume is the same (including air) and you force the same amount of water into each, then the pressure will be equal in the single and dual chamber guns. Shot times till drop-off on the same nozzle (with equal pre-charge) would also be identical between them as the water/air ratio's are the same.
Actual reasons to use one instead of the other likely come down to ascetics, the ability to mold a shape, and the amount of plastics required to make a given chamber shape safe.
Re: Number of Pressure Chambers
Posted: Sat Apr 04, 2015 5:27 pm
by SSCBen
You can ignore everything technical that I said before 2009 or so. In the past I did say force mattered, so the surface area on the water was important and this would make two chambers work better than one, but this thinking is totally wrong. You can look at Bernoulli's principal and whatnot and see that the pressure is what matters.
I'm not entirely sure, but one important factor comes to mind. Two chambers could support higher flow rates more easily. Larger pipes mean slower flow, which means less turbulence. This effect becomes less important as the pipe sizes increase, but for guns with smaller pipes like XPs, it is likely critically important.
the oncoming storm is right that there may be manufacturing concerns as well.
Re: Number of Pressure Chambers
Posted: Tue Apr 07, 2015 8:57 am
by marauder
I thought the 105 had decent sized pipes. The reason, and this is just a guess, that I think the 105 has poor range is because it's second PC is so small in relation to it's pump volume. I think the smaller PC only holds like 3 oz and it ends up becoming less pressurized than the larger pc.
Re: Number of Pressure Chambers
Posted: Tue Apr 07, 2015 10:02 am
by the oncoming storm
Marauder if someone has two 105's then we could test this hypothesis with some shell modifications, I developed the same theory quite separately from you back last year.
My theory was that due to the low volume of the chamber compared to the nozzle aperture size that the pressure drops so much while the valve is opening that by the time it is fully opened firing pressure has been reduced and thus range
Re: Number of Pressure Chambers
Posted: Tue Apr 07, 2015 10:57 am
by marauder
Rob has a 105 and Scott has a 105. I'm sure there's more on the forum.