O Rings vs swell sealing

[Flash]

Newbie here, just checking to see what your friends like best, heating and swelling a PVC lunch rod to make seal with bottle opening or using the O-ring design, and why please.

Thank you!!!
Flash

[bugwubber]

I have both styles of launch tubes. Each does a fine job. When I wanted something quick and didn't have o-rings and 1/2" cpvc on hand, I went with the swell design. When I wanted to precisely place where the seal was positioned, I went with o-rings.

The o-ring design also allows for some movement of the rocket into your release mechanism.

Bugwubber

[Flash]

Thank you very much!
I like the idea of movement that you mentioned. Things under use to get out of adjustment that is for sure.

[Nick B]

mostly the tapered, swelled tube.

Dunno about the heating to swell. Do you have a link?

[Tony]

I like the concept behind the o-ring, and there is a tutorial on the Air Command youtbue site that makes it simple, but I have never used it. I needed to build my launcher as cheaply as possible, so I went with heat swelling, and it has worked great for me for over 100 launches.

When I rebuild my launcher I will probably go with the o-ring design.

[bugwubber]

mostly the tapered, swelled tube.

Dunno about the heating to swell. Do you have a link?

Just take your tube, draw a straight line around it
Insert a dowel to keep the pipe straight or plan for a straight edge with a gap in the middle
Using a candle or heat gun, evenly heat your line.
When the PVC softens, push the pipe ends towards each other while keeping the pipe straight.
This should create a slight bulge(don't need much)
Hold the pipe straight until it hardens again.

This type of seal can be used like a cork release or you can add cable tie release.

[Nick B]

mostly the tapered, swelled tube.

Dunno about the heating to swell. Do you have a link?

Just take your tube, draw a straight line around it
Insert a dowel to keep the pipe straight or plan for a straight edge with a gap in the middle
Using a candle or heat gun, evenly heat your line.
When the PVC softens, push the pipe ends towards each other while keeping the pipe straight.
This should create a slight bulge(don't need much)
Hold the pipe straight until it hardens again.

This type of seal can be used like a cork release or you can add cable tie release.

Interesting.

I just tap and NPT nipple mine to get the tapered expansion of the bottom dia, and the launcher mating.

I'll need to try that some time.

[U.S. Water Rockets1]

I have both styles of launch tubes. Each does a fine job. When I wanted something quick and didn't have o-rings and 1/2" cpvc on hand, I went with the swell design. When I wanted to precisely place where the seal was positioned, I went with o-rings.

The o-ring design also allows for some movement of the rocket into your release mechanism.

Bugwubber

A drawback of the swelled pipe seal is that it will usually leak after time and use, and it is easier to jam so the rocket will not release. We prefer the -ring seal because the seal can be replaced if it gets worn out.

Our tutorial on adding o-rings to a launch tube is located at this link:
http://www.uswaterrockets.com/construct ... torial.htm

[Nick B]

I have both styles of launch tubes. Each does a fine job. When I wanted something quick and didn't have o-rings and 1/2" cpvc on hand, I went with the swell design. When I wanted to precisely place where the seal was positioned, I went with o-rings.

The o-ring design also allows for some movement of the rocket into your release mechanism.

Bugwubber

A drawback of the swelled pipe seal is that it will usually leak after time and use, and it is easier to jam so the rocket will not release. We prefer the -ring seal because the seal can be replaced if it gets worn out.

Our tutorial on adding o-rings to a launch tube is located at this link:
http://www.uswaterrockets.com/construct ... torial.htm

I still cannot get a reliable o-ring seal at higher pressures with the o ring launch tube setup. Depending on the rocket, I get a good seal, or a seal leak, blow by at around 180 to 220 or higher psi.
I am also having failures of the three piece launch tube design. I am switching to NPT nipple for my joining of the assembly, so that I do not have PVC glue failure, and rockets launching with half their launch tube onboard. lol

[bugwubber]

I have both styles of launch tubes. Each does a fine job. When I wanted something quick and didn't have o-rings and 1/2" cpvc on hand, I went with the swell design. When I wanted to precisely place where the seal was positioned, I went with o-rings.

The o-ring design also allows for some movement of the rocket into your release mechanism.

Bugwubber

A drawback of the swelled pipe seal is that it will usually leak after time and use, and it is easier to jam so the rocket will not release. We prefer the -ring seal because the seal can be replaced if it gets worn out.

Our tutorial on adding o-rings to a launch tube is located at this link:
http://www.uswaterrockets.com/construct ... torial.htm

I still cannot get a reliable o-ring seal at higher pressures with the o ring launch tube setup. Depending on the rocket, I get a good seal, or a seal leak, blow by at around 180 to 220 or higher psi.
I am also having failures of the three piece launch tube design. I am switching to NPT nipple for my joining of the assembly, so that I do not have PVC glue failure, and rockets launching with half their launch tube onboard. lol

Have you tried the #90 hardness rating o-rings? Would expect you'd need to cut the groove in with a lathe on a double wall pipe section so the o-ring is fully supported

[Nick B]

[

Have you tried the #90 hardness rating o-rings?

Not sure anymore.

I lost the packaging on the rings. I have three types at this time. The first ones were thicker and harder.

[U.S. Water Rockets1]

Since our o-ring design he retained by the cable ties, the pressure in the rocket is not pulling any of the o-ring components apart, so there's no chance of the design launching itself due to pressure in the launch tube. We suggest you use a method like ours, instead of whatever you're currently using.

http://www.uswaterrockets.com/construct ... torial.htm

[Nick B]

Since our o-ring design he retained by the cable ties, the pressure in the rocket is not pulling any of the o-ring components apart, so there's no chance of the design launching itself due to pressure in the launch tube. We suggest you use a method like ours, instead of whatever you're currently using.

http://www.uswaterrockets.com/construct ... torial.htm

Dunno.

It has happened on three launchers. The cross pin, the cable tie, and the swelled taper when using the three piece design. albeit, less often with the retention ones. I think it has more to do with an incompatibility with the pcv cement, since I use a piece of cpcv for the inner segment.

Another thought, Mine has no downward pressure on the pipe during launch like yours may with your upper cup/sleeve/tube receptacle in your X12

[bugwubber]

I use primer and "all purpose" cpvc/PVC cement. Although I do not operate at the pressures you do, the bonds have been excellent.

[Nick B]

I use primer and "all purpose" cpvc/PVC cement. Although I do not operate at the pressures you do, the bonds have been excellent.

Yeah.

We don't always use primer, or sand our surfaces for a better grip. I think we just suck at pvc adhesive work. lol


I still think the swelled tapered tube is a better option of the two.