Transparent Air Tank

[Knufire]

Does anyone know/have a source for a transparent air tank? I've been looking for one for a different competition; they want to be able to see within the tank to make sure we're not adding anything to the air. It'll be storing air around 100psi, so anything rated for 120psi or more should be fine. Volume would be around typical FRC usage as well (~500mL).

[Taylor]

Would an aquarium work?

[Wren Hensgen]

You're not going to find many of these, sadly. There aren't many clear plastics that play nice with high pressure. You can MAKE one of transparent ABS, but that has a nasty habit of exploding under too much pressure.

Which competition is this? Would a glass or plastic porthole into the tank be acceptable? A sight glass is a very easy way to add visibility to a process. They're designed to add a visible port to watch oil levels in systems where that's required.

https://www.amazon.com/Compressor-Fi.../dp/B00880DXQC

https://www.amazon.com/Thread-Diamet...YG6E 2RZQG0H7

https://www.amazon.com/W-Anderson%C2...7KC8 D5N41ADP

[Knufire]

Originally Posted by Wren Hensgen

Which competition is this? Would a glass or plastic porthole into the tank be acceptable?

Shell Ecomarathon. The tank would be providing pressure to the fuel injector for a small engine. The rationale behind the rule is to ensure that we're not premixing fuel with the air, though the implementation seems to be poor.

Originally Posted by SHELL ECO-MARATHON
2017 OFFICIAL RULES. CHAPTER I

b) It is permitted to pressurise the liquid fuel tanks, in order to feed the engine, only under the
following conditions:
i. Pressurisation is done by means of a translucent compressed air bottle fitted with a safety
valve set to 5 bars maximum – or the lower operation pressure of the vehicle system.

Most teams seem to be jerry-rigging something out of a 20oz soda bottle; seems less safe to me than just letting use COTS storage tanks.

[MrForbes]

you could make one, using aluminum end caps, and Lexan™ round tube, sealed with O rings. We used them on our underwater robots (link below), you'd have to do the engineering necessary to make sure it's safe, of course.

[Wren Hensgen]

Originally Posted by Knufire

Shell Ecomarathon. The tank would be providing pressure to the fuel injector for a small engine. The rationale behind the rule is to ensure that we're not premixing fuel with the air, though the implementation seems to be poor.



Most teams seem to be jerry-rigging something out of a 20oz soda bottle; seems less safe to me than just letting use COTS storage tanks.

I would absolutely just put a sight glass or two into the bottom, so they can see that there's no liquid in the tank. See my last post for some examples.

[Chris Fultz]

I have one of these on my compressor to keep moisture out of nail guns.
You can plumb it directly into the system and not have to modify the tanks.


https://www.amazon.com/Water-Separat...sor+water+trap

[ctt956]

Originally Posted by Chris Fultz

I have one of these on my compressor to keep moisture out of nail guns.
You can plumb it directly into the system and not have to modify the tanks.


https://www.amazon.com/Water-Separat...sor+water+trap

I had the same idea. It would also filter water out, though water may look like fuel...adding a transparent section of pipe may also work.

[RoboChair]

Originally Posted by Knufire

Shell Ecomarathon. The tank would be providing pressure to the fuel injector for a small engine. The rationale behind the rule is to ensure that we're not premixing fuel with the air, though the implementation seems to be poor.



Most teams seem to be jerry-rigging something out of a 20oz soda bottle; seems less safe to me than just letting use COTS storage tanks.

2 liter bottles are good to about 120psi before failure, 20oz is probably a fair bit higher. You can do some destructive tests first. I would suggest clear polycarbonate tubing which you can buy from McMaster as you can use pipe fittings with it.

Alternatively just use a long piece of clear hose.

[Bob Steele]

Depending on volume you might try a soda preform. See below
https://www.amazon.com/Soda-Bottle-P.../dp/B008MB1QNY

[IKE]

Originally Posted by RoboChair

2 liter bottles are good to about 120psi before failure, 20oz is probably a fair bit higher. You can do some destructive tests first. I would suggest clear polycarbonate tubing which you can buy from McMaster as you can use pipe fittings with it.

Alternatively just use a long piece of clear hose.

I too was thinking along these lines. Most safety standards with regards to pressure vessels want a 2.3 Safety factor, so if the burst pressure is 120 PSI, then filling up to 50 PSI would be the responsible thing to do. I know for water rocket competitions, a lot of folks regularly fill them to 70 PSI (about a 1.5 SF).

The stresses should be lower on a 1 liter bottle which may be able to get a higher rating.

[Andy Brockway]

Many air filters are similar to the water separator already mentioned, you could remove the filter if needed.

[Wren Hensgen]

If you're talking about a standard rectangular tank, you'll just blow out the side walls because of the pressure. If you're modifying something, you'll have to be extremely careful, as the glass is not pressure rated, and is likely to shatter under stress.