16 replies to this topic

[Lt Stefan]

When I first made my PVAT, I used a quick connect fitting I bought from Home Depot. When I tested the tank, it was leak free except for that fitting. the air came out of where the tube went into it. Was I doing something wrong? Was the fitting not meant to handle pressure? I've seen people use these kind of fittings before and they have worked so I don't know what is going on.

[Split]

Are you sure you pushed the tubing in all the way? You shouldn't be able to pull it out without pushing down on the collar. I've used them to hold normal nerf gun amounts of pressure just fine though.

[Lt Stefan]

Yeah I used the specified tubing size and pushed them in all the way. The tube couldn't come out without holding the rings down.

[roboman]

When you use those fittings, you have to make sure the tubing ends are as square as possible, or else the fitting may not seal properly. If the ends are at all chewed up, it may also inhibit a proper seal.

Had the fitting ever been used before? Often, they begin to leak after 5-10 insertion cycles, and must be replaced.

EDIT: After re-reading the PVAT thread, I noticed you used a hose barb on the tank, instead of an actual quick-connect. Is this what you were referring to as a "quick connect fitting?"

Edited by roboman, 29 March 2010 - 04:56 PM.

[Lt Stefan]

It was a virgin fitting. The tube I inserted had a clean end as well. I cut it with a razor, and was about as close to 90 degrees as humanly possible.

Did I maybe get the wrong type of fitting or tubing? (i.e. made for water?)

[roboman]

What kind of tubing was it? Was it pressure rated, and meant for pneumatics?

[Fome]

It may just be defective. Goop could make a nice seal, however that sorta defeats the purpose of the instant tube fitting.

[Lt Stefan]

It was vinyl tubing that I got from Home Depot. That's what most everyone else uses.

Where do you guys find your quick connect fittings?

[roboman]

I get my tube and fittings from either Ace, Monster Guts, McMaster, or Grainger. I love the Monster Guts tubing, since it's black, shiny, and really flexible.

[Draconis]

When I first made my PVAT, I used a quick connect fitting I bought from Home Depot. When I tested the tank, it was leak free except for that fitting. the air came out of where the tube went into it. Was I doing something wrong? Was the fitting not meant to handle pressure? I've seen people use these kind of fittings before and they have worked so I don't know what is going on.

A picture would be helpful, so that we know exactly what you are using.

[CaptainSlug]

It was vinyl tubing that I got from Home Depot.

That soft of a tubing is not compatible with quick-disconnect fittings. I prefer to not use vinyl tubing because it has a low pressure rating, and it kinks
Quick-disconnect fittings are made for a certain family of tubing. The most common tubings that are compatible are polyurethane, Nylon, polyethylene, PEX, and polypropylene. All of which are a higher durometer rating (stiffer).

Edited by CaptainSlug, 29 March 2010 - 10:27 PM.

[Lt Stefan]

It was vinyl tubing that I got from Home Depot.

That soft of a tubing is not compatible with quick-disconnect fittings. I prefer to not use vinyl tubing because it has a low pressure rating, and it kinks
Quick-disconnect fittings are made for a certain family of tubing. The most common tubings that are compatible are polyurethane, Nylon, polyethylene, PEX, and polypropylene. All of which are a higher durometer rating (stiffer).

Which one would you recommend for our applications? And is there a specific type of fitting for high pressure or will anything do?

[roboman]

Which one would you recommend for our applications? And is there a specific type of fitting for high pressure or will anything do?

Personally, I use polypropylene. At Ace, it costs ~$1.15/foot, and is rated to 150 psi. Nerf usually doesn't use "high pressures," so just about any fitting will do.

[Lt Stefan]

In case anyone wants to know, this is the fitting. Where do you guys get yours?

[roboman]

I really like Mcmaster fittings. They're relatively inexpensive, and are made of stainless steel.

Edited by roboman, 31 March 2010 - 08:35 PM.

[CaptainSlug]

I tend to prefer polyurethane tubing because it has a good mix of kink resistance while still having a fairly narrow bend radius.

I really like Mcmaster fittings. They're relatively inexpensive, and are made of stainless steel.

That's a rather vague suggestion. McMaster supplies a complete variety of quick-disconnect fittings, available in several different materials and suitable for different tubing materials.

Edited by CaptainSlug, 31 March 2010 - 09:34 PM.

[Lt Stefan]

I think polyurethane tubing and fittings to go with it are going to be my new choice from now on.