Different check valves

[mr. dude]

I'm redesigning my APH, as the original design was such a failure. So that got me thinking, should I change the check valves as well? The kind I have is the one that relies on gravity to shut the valve, meaning I can't point the gun downward, otherwise the check valve will open.
I definately want to change the one that starts the PC to the spring-loaded kind, but is it really worth it to spend that extra money for the second valve? There's a huge price difference, 1" brass (gravity-relying?) valves are $17cdn, while 1" brass spring-loaded are $40cdn. Please note I don't actually want to use 1", I use 3/4" (couldn't find any 1/2").
Is it worth it to shell out the extra money, or does it not matter with the pump?

[C-A_99]

What was your homemade design? And why do you have to use brass instead of PVC?

[Silence]

PVC seems a lot cheaper, so I'd try to get ahold of that. But spring-loaded valves are definitely better. I'm actually surprised the pressure on the other end doesn't keep the valve closed, at least not once pressure has managed to build up.

You can make your own valves; take a look at the designs Waterzooka and I were discussing. I'm pretty sure brass valves are swing valves, which is why they're shorter.

You might be able to get cheap valves from McMaster-Carr. Shipping probably won't take too long, and they have a wide selection.

[mr. dude]

What was your homemade design? And why do you have to use brass instead of PVC?

My design used a 3/4" pump and 1" PC, so I couldn't build any pressure with it. I use brass because it's all I can find. The only other thing I could find was 1 1/4" ABS, but that's not what I'm looking for.

You might be able to get cheap valves from McMaster-Carr. Shipping probably won't take too long, and they have a wide selection.

Not an option. I need a credit card for that, my parents won't use theirs, and I'm 4 years too young to have a credit card.
I'll try to find PVC, but that still doesn't answer my question, should I replace both or will the pump-reservoir one be fine?
Also, is all schedule 40 PVC pressure rated? If not, then I will need to do some searching for it.

[Silence]

Not all PVC is pressure rated. If it says "cell core" on the side, then it isn't. If it says "Schedule 40" or "Schedule 80" or something, and if it has a number saying the max PSI, then it is pressure rated.

I'm sure there are some plumbing or hardware stores that carry it. But yes, it will probably take some looking. I'd use the yellow pages in the phone book.

On second thought, gravity check valves should work perfectly fine. Why do I suddenly say that? Because you'd have a problem when upside-down even with spring-loaded check valves--with the PCs. The PCs are designed for the water to be on the bottom. If you shoot while upside-down, then only air will come out anyway.

Not that you'd be upside-down while pumping or shooting anyway. It might be a good idea to have the second check valve spring-loaded, in case you're carrying the gun upside down.

[mr. dude]

My local home depot has schedule 40, but only the ball valves have a number on them (150 psi).

[C-A_99]

Most, if not all of the sch40 PVC at Home Depot should be pressure rated. I think it was around 260psi at 73 F/23 C. At Lowe's, anything around 2" or above is cellcore. (I'm not sure exactly where they start using cellcore) You can still use any cellcore pipe for the reservoir, unless you're using a pressurized reservoir setup. (the cellcore pipe is lighter of course)

[mr. dude]

Looking through my pvc, it's all schedule 40, but only the ball valve has a pressure rating (150psi at 73 degrees). I'm going to resort to asking my friend for some.
As for the swing valve, I'm going to use it for another refill station I guess.

[Silence]

It should be pressure rated well enough if it's Schedule 40. However, I'm not sure of that, so I would advise asking for friend.

EDIT: I know CROC resorted to using metal tubing and fittings, and you guys live in the same place. So I doubt you'll be able to find PVC if you can't go to a plumber's place or something.

[CROC]

Technically, we dont live in the same place, or I would have been slapped for something over on WaterWarfare forums already

I got the metal fittings because of a few things
a)There is no such thing as 3/8" PVC
b)The closest plumbing store was closed on that day

I would recommend trying to make the homemade check valves on the second page of my "Idea for a homemade" thread. If you must have the PVC though, then go to the plumbing store on any weekday other than Sunday
Mr. dude, if I go to the plumbing store I will pick you up some check valves- what size do you want?
~CROC

[Silence]

Yeah, it might be worthwhile to make your own check valves , if you can find the parts. Brass is far more expensive than PVC, and it sounds like you can get smaller sizes in PVC (3/8" exists, it's just too uncommon for most stores to carry it).

[mr. dude]

I checked today (by phone), and the plumbing store Croc referred to does have pressure-rated PVC, though it's only 125psi. And they have PVC check valves, so I'm happy.
And since when was it dangerous to have pressurized air in PVC? That's what the man at the store said.

[C-A_99]

^It isn't, you just have to watch the PSI level, as it's safer to limit pressurized air to a lower PSI than you would with water.

If it was dangerous, there would be no APH's, no air pressure WBL's, etc.

[mr. dude]

Exactly, that was the whole point when I said that. Plumbers are supposed to know about water guns, jeez!
What pressure levels do APH's normally get to? I know that XP's get 40psi, but that doesn't help me at all.

[Silence]

The warning about using pressurized air only applies to industrial applications--involving powerful pumps. Each time such a pump cycles, a surge of pressure is created. The water hammer effect can top the stress capability of PVC easily. That's why they'll suggest metal tubing for applications involving industrial pumps.