SpudFiles

I'm looking to replace the schrader valves on my guns because they are too slow to attach to my pump....
I got a few questions related to quick disconnects so bear with me...

Witch quick disconnect can act like a schrader valve?
Can you disconnect them under pressure?
How much pressure can they hold?
Should I be looking for pneumatic or hydraulic fittings?

FighterAce wrote:Witch quick disconnect can act like a schrader valve?

Not sure what you mean by that.

Can you disconnect them under pressure?

Yes, although most do not have a built in check valve.

How much pressure can they hold?

Totally varies with model. I've seen pneumatic ones anywhere between 7 bar and 70 bar. (Presumably to roughly correlate with 100 and 1000 psi).
Really don't know about hydraulic ones - never looked for them, wouldn't even be certain they exist.

Should I be looking for pneumatic or hydraulic fittings?

Mostly depends on what pressure you need, but I'd go pneumatic unless you have to.

It depends what pressure you want to use. I'm not sure about QCs with check valves but I always add a ball valve to control how much air gets through and when. You can also pilot guns through the ball valve if you want. Disconnecting them and connecting them gets hard after 100 psi for me, but it can be done. If you are looking at like fridge compressor pressures then you need a venting system to make it easier.

Thanks!

Ragnarok wrote:

FighterAce wrote:Witch quick disconnect can act like a schrader valve?

Not sure what you mean by that.

As I understand it, there are 2 types of quick disconnects... ones that have built in check valve and ones that dont... not sure if they have any specific names. How can you tell witch is witch?

I'm gonna be using a pump like I said... it goes up to 40 bar.

And I'd really like to avoid ball valves as much as possible.

If you have a female QC on our gun It will work exactly how you specifically need it to work, but in order to connect it to an air compressor you would need a male QC adaptor

Please, stop mentioning air compressors I dont have one and dont plan on getting one anytime soon.

So... the female QC on the gun and male QC on the pump hose I guess.

Any word of advice on reliability? Will I need to open it up (if I even can) and replace any O rings after a while?

nope, they hardly ever break down, I've never had one break on me or even leak.

FighterAce wrote: So... the female QC on the gun and male QC on the pump hose I guess.

correct

Guess I'm locked n loaded to go shopping

Thank you all for the help.

Be careful with the cheap ones you get for like 2.50 from Home Depot. If you wiggle the connection it will leak and they are rather cheaply built. I reccomend the 8 dollar ones with the 3/8" connection. They are universal and don't leak and are much stonger and well built.

As long as you keep them under 250 psi, you should be able to disconnect them without draining the hose of pressure. Otherwise, you have to have a ball valve on the gun (even female QDs don't have a check valve, so if you try and drain the line without closing of the guns chamber with some sort of valve, the pressure will exit the guns chamber, because when a female and male QD are connected, the air has a straight path through) and a
Drain valve.

my 1/4 Qc valve from home depot was 5 bucks for both a male and a female part, i have used them up to 850 psi many many times.

You WILL need a ball valve, because you simply can not disconnect them under more than 200psi. ... at least.... not with your hands.

@BeaverRat, FQCs definitely have a check valve. They close themselves when there is no male QC inserted. (TWSS)

FighterAce wrote:Witch quick disconnect can act like a schrader valve?

Umm.... None. Schrader valves act like schrader valves.

Can you disconnect them under pressure?

Most of them, yes, but there are QDs that are designed to NOT be disconnectable under pressure. These tend to be specialized parts, however, and not something you're likely to find unless you're looking for them.

How much pressure can they hold?

It all depends... I've got some hydraulic QDs at the office that are good to 7,000 psi.

Should I be looking for pneumatic or hydraulic fittings?

It entirely depends on what you're trying to do... Which you haven't really stated. My money is on pneumatic, however. The demands of spud guns aren't particularly demanding.

I use s pneumatic QD with check valve on my hybrid. It shoots around 200psi and has held up fine to hundreds of shots with no leaking.

Gun Freak wrote:@BeaverRat, FQCs definitely have a check valve. They close themselves when there is no male QC inserted. (TWSS)

I never said they didn't close themselves when there is no male QC I simply stated that if you are at pressures above say 300 PSI, where it is nearly impossible to remove a QD female from a QD male, you must first drain the line pressure. Since the check valve is forced open when the male is in the female socket, draining the line before disconnecting will also drain the chamber. Where if there was a true stand alone check valve, the pressure couldn't leave the chamber, even if there was a male QD in the female socket. I stated (very messily) that an alternative to buying a check valve, would be to put a ball valve behind the female (or male) QD on the cannon, and a line drain somewhere else.