Wich gas use?

Lentamentalisk · Sat Mar 07, 2009 12:33 pm

oops sry, I misthought sry sry sry.

Yes, air may be "better" but that is qualitative and unspecific. First of all, it is not one of the 3 choices we were offered. Second, it may be cheaper, if you have a scuba or paintball shop around, but it also requires a heavy high pressure tank, or a $200 carbon fiber tank, if you want to store a reasonable amount of gas. Also, you need a paintball or scuba shop, which it seems like our man here doesn't have, seeing as how he wants to use gases from the hardware store. Last but not least, CO2 and HPA both require an expensive regulator, because they run at such high pressures, unlike propane, which runs at 50-180psi depending on temp.

In some cases it is better though. For example, anything stored as a liquid, though more dense, will vary pressure dramatically with temperature, and will begin to freeze if you use it too quickly, because the gas needs to boil off.

Demon · Sat Mar 07, 2009 12:35 pm

By air you mean oxygen?

Lentamentalisk · Sat Mar 07, 2009 12:39 pm

by air, i mean HPA. Oxygen is something entirely different. the air we breathe is only 21% oxygen

Oxygen is not one of your options. It either will have next to no air in it at all, or will cause something to detonate in your face.

As for the fire hazard of propane, it depends on what your conditions are. If you are playing outside, then you are fine. Even the slightest breeze will blow it all away. I would not use it inside though.

john bunsenburner · Sat Mar 07, 2009 12:40 pm

No by air we mean air 20%oxygen 79%nitrogen and 1%argon(some other gasses are also in this mixture)

Demon · Sat Mar 07, 2009 12:52 pm

There is a refuelling port on the side of the bottle, is it an standard one so i can refill in paintball stations or an special fitting one?I mean by special that its hard to get.

What psi can handle the cylinders?

john bunsenburner · Sat Mar 07, 2009 12:54 pm

Which cylinders?

roboman · Sat Mar 07, 2009 1:40 pm

@John: I'm guessing he's asking about HPA/CO2 cylinders. And yes, if you use a paintball tank, they have a standard fitting for refills.

If I were you, I wouldn't use mapp or propane in a pneumatic. They smell really bad, and if you plan to use bottles from the hardware store it can get really expensive. HPA or CO2 are your best options here. At Harbor Freight, they sell a cheap CO2 regulator for ~$45. Also, you can get CO2 for that at Lowes or Home Depot.

ramses · Sat Mar 07, 2009 1:52 pm

hpa tanks can take up to 4500psi, but the pressure drops with use CO2 pressure varies with temperature, and the pressure doesn't necessarily drop with use. CO2 tanks get cold with use, and should be used with a metal expansion chamber, as coldness makes pvc brittle.

john bunsenburner · Sat Mar 07, 2009 2:43 pm

HPA pressure varies with pressure too of coarse, but not quiete as much. And you cannot control the pressure you get from tank refills for HPA and CO2, so i was not sure if that was the cylinder ment

Lentamentalisk · Sat Mar 07, 2009 2:48 pm

practically, HPA doesn't vary with pressure. A drop in temperature from room temp to freezing will decrease the pressure by ~7%, where as with propane, going from room temp to freezing is at least a 50% drop in pressure. Besides, if you are using HPA not regulated down to more practical pressures, then you have much bigger problems to worry about than temperature changes.

Back on topic, your best choices are either propane, or splurge and go for a nice CO2 setup.