Clunk Tank flexible tubing

[Allen Eshleman]

What are the best flexible tubings available for inside a clunk tank?

Hayes tanks have black (surgical??) tubing.  Is that good stuff?  Then there's blue silicone tubing available at Brodak and also a brownish or yellowish surgical tubing available at Brokak - only in large or small.  (These are for reference of things I have already looked at.  However, there may be others.

A related question is - how often should that tubing be changed or updated?

Thanks ahead of time.

[Windwalker]

I just changed the tubing in the clunk tank on my engine test stand.. I used the blue tinted tubing from Brodak.. It's more flexible than the others.. lI've got some tubing that is over 20 years  old.. It's on my fuel can, but I wouldn't trust it on an airplane..

Nick

[Dave Moritz]

Allen:

Texas Timers sells a very flexible line in two small sizes. The larger size works well for the clunk tanks feeding the motors I run (.20 and below, even with a one-ounce tank). If the fuel draw isn't too great, then it might even work for larger engines but I've no experience there.

It takes a little work, but the small size will go onto a 1/8" pipe if the external pipe edge is chamfered a bit. As far as clunks go, fittings on them tend to be too large. The solution is either a bit of filing or drilling and soldering in a short length of 1/8" pipe.

Dave Mo...

[George Truett]

Allen,  Ever since I first tried it around 1980, I have used nothing except Prather products fuel tubing for all of my fuel lines.  It was not available for a while but a quick search finds it in stock at several hobby shops.  For .15 all the way to .60 and bigger, the Medium tubing works well, it's a pinkish/red color.  I plumb inside the tank with it and also the fuel line to the engine.  For a vent or pressure line, I use blue tubing so that my lines are color coded.  I liked the blue Aerotrend but it's long gone, my latest roll is Venom I believe.  I like and use Kraft tanks whenever possible but I am not a fan of the black tubing that comes with them, it didn't last very long for me.  My experience with the Prather tubing shows it lasting many years.  If it does not seem flexible enough for you, replace the middle portion of tubing inside the tank with 1/8" brass tubing.  You will end up with brass tubing through the tank stopper, a short piece of Prather line, a couple of inches of brass tubing, another piece of Prather line and finally, the clunk.  That configuration will always flop to the appropriate side of the tank but will not let the clunk go to the front of the tank if you have an abrupt stop ( I have had that happen and it will have you scratching your head).  The brass tubing submersed in fuel will probably deteriorate faster than the Prather tubing so keep an eye on it or replace every few years.

[Dan McEntee]

Allen,  Ever since I first tried it around 1980, I have used nothing except Prather products fuel tubing for all of my fuel lines.  It was not available for a while but a quick search finds it in stock at several hobby shops.  For .15 all the way to .60 and bigger, the Medium tubing works well, it's a pinkish/red color.  I plumb inside the tank with it and also the fuel line to the engine.  For a vent or pressure line, I use blue tubing so that my lines are color coded.  I liked the blue Aerotrend but it's long gone, my latest roll is Venom I believe.  I like and use Kraft tanks whenever possible but I am not a fan of the black tubing that comes with them, it didn't last very long for me.  My experience with the Prather tubing shows it lasting many years.  If it does not seem flexible enough for you, replace the middle portion of tubing inside the tank with 1/8" brass tubing.  You will end up with brass tubing through the tank stopper, a short piece of Prather line, a couple of inches of brass tubing, another piece of Prather line and finally, the clunk.  That configuration will always flop to the appropriate side of the tank but will not let the clunk go to the front of the tank if you have an abrupt stop ( I have had that happen and it will have you scratching your head).  The brass tubing submersed in fuel will probably deteriorate faster than the Prather tubing so keep an eye on it or replace every few years.

     I will echo George's comments and recommend regular fuel line is all that is necessary, and although I have not heard about it, if there is indeed a new source for Prather fuel line, it is my preferred fuel line also. I have experimented with the colored stuff that Du-Bro sells pre-packaged in 2 or 3 foot length and they have some that looks and feels just like the Prather line but is yellow in color and it works well, better than their standard blue silicone fuel line. The plastic tanks are cheap, easy to set up and serviceable, but once you have them set up and working correctly, you hate to disturb things just to change fuel lines. If you use stuff that is to soft and loosie goosie, you can get the problem of it falling forward in the tank and getting stuck there. The softer, looser tubing doesn't last as long either, and part of the problem with that is if you don't fly the model very often, or it sits un-used for long periods of time, it can deteriorate a little faster. The trick, I find,  is to keep the copper tube through the cork for the pick up to a minimal length. The longer the pick up fuel line is, the better it will move around.
    Type at you later,
      Dan McEntee