View Full Version : A tube burst-What happened?
parkedraccoon
20-05-2012, 16:00
We had an outreach event for our team yesterday, and we were displaying our robot, driving it around, running the shooter, etc. Then we heard a very loud pop and one of our team members immediately pressed the power switch. We went over to take a look and found this:
http://i.imgur.com/gf2CB.jpg
Something crazy must have happened here. By looking at the whole, it looks like the tubing melted, which made the tubing thinner. Would the heat from that compressor (I believe it's the small one that is prone to overheating) be able to weaken the tubing enough to have it pop?
We were using the compressor for extended periods of time, due to using large amounts of pressure for our center wheels, which use up like 1-2 large PVC tanks of air per full cycle.
Tom Line
20-05-2012, 16:09
The new compressor isn't prone to overheating - but you do have to pay attention to its duty cycle and not run it all the time. That's true of all compressors though.
I have seen the compressor (run constantly) melt pneumatic tubing. It's a good bet that's what happened.
Was it hot out? I heard (from across the tent) this happening to 469 at IGVC last year. The 100 degree heat combined with the short match turnarounds caused the tubing near the compressor to melt and burst.
parkedraccoon
20-05-2012, 16:31
Was it hot out? I heard (from across the tent) this happening to 469 at IGVC last year. The 100 degree heat combined with the short match turnarounds caused the tubing near the compressor to melt and burst.
I wouldn't say it was extremely hot out, but it was warm. And we had been running the robot for something like an hour when this happened.
Compressors make heat. Hot enough to cause serious burns even under normal usage.
It's important to not use a push-on fitting connected directly to the compressor like that. Get some brass (t-fitting or extension tube) between the compressor and that fitting to help dissipate the heat before it gets to the hose.
Compressors make heat. Hot enough to cause serious burns even under normal usage.
It's important to not use a push-on fitting connected directly to the compressor like that. Get some brass (t-fitting or extension tube) between the compressor and that fitting to help dissipate the heat before it gets to the hose.
What he said! We had the tube burst thing happen a lot with our practice robot this year, too, until we put some "insulation" between the outlet and the first push in tube. The new "little" compressors do run quite hot, enough to cause what you saw happen. Definitely need to cool the output side however you can manage to do it.
PV = nRT
hot gas coming out....
RayTurner1126
20-05-2012, 17:35
same thing happened to our 2011 bot when running demos. just over-ran it a bit, bet that's what happened here.
JonathanZur1836
20-05-2012, 20:39
Yeah, the above posts are probably correct in that heat from the compressor caused the rupture. I would definitely suggest either brass or nylon fittings anywhere near the compressor, brass being the safer but mildly heavier bet.
Heat defiantly was the murderer but also replace that T just in-case there is a weird constriction.
Gotta love the internet.
There's even a website (http://www.d-e-f-i-n-i-t-e-l-y.com/) for that :)
Gotta love the internet.
There's even a website (http://www.d-e-f-i-n-i-t-e-l-y.com/) for that :)
It was the right spelling, just the wrong word.
Al Skierkiewicz
21-05-2012, 08:30
Same thing happened to a team at Midwest last year. The team had been checking for a problem leak and couldn't find it. They had the compressor running continuous for about 15-20 minutes. When the tubing let go it was like a firecracker.
I have to ask, it looks like your compressor is discolored. Is it covered in something? Did it get contaminated?
If you are going to run the compressor for long duty cycles, especially out in the heat, maybe you should put a length of copper tubing, preferably with cooling fins, out of the compressor for a couple of feet.
Because of PV=nRT the gas is coming out very hot and directly hitting the tubing.
I would bet in commercial applications the air is already cooled before it is distributed around a plant and delivered to systems using the flex tubing. In commercial plants that has to deliver a lot of air they may even push the air through a heat exchanger to cool the gas before storage and delivery.
If you have a shop air compressor you can, but SHOULD NOT touch, the copper tube from the compressor head to the storage tank. After it runs is is very hot, and if you touch it may burn your hand.
The air in the tank now has a new set of dynamics and moisture will condense, rain, into the bottom of the tank. That is why there is a valve on the bottom of the tank, so you can drain the condensate, but I digress.
PV=nRT
Al Skierkiewicz
21-05-2012, 10:20
I would bet in commercial applications the air is already cooled before it is distributed around a plant and delivered to systems using the flex tubing. In commercial plants that has to deliver a lot of air they may even push the air through a heat exchanger to cool the gas before storage and delivery.
Ed,
Just received a new scene shop compressor that will be used for tools in building sets. It is a two stage compressor where the output of one piston enters a second piston. That pipe is finned and passes in front a fan that also passes air through the output heat exchanger. I have been asked several questions about "radiator" on the new compressor.
Our 100 HP plant air compressor discharge is 190 F @ 100ish psi. It goes thru an air to air cooler & is about 120F before the dryer. Discharge of the dryer is about 90F. It goes into a steel storage tank. By the time it gets to the process it is more or less ambient. The expansion acts in the other direction & cools it.
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