Bladder Fuel Tanks
02-27-2006, 10:27 PM
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Bladder Fuel Tanks
Hello All
I am new to racing, actually just getting started, and I see that most use bubbleless bladder tanks in their planes. I have a couple of questions regarding their use.
1. I see that there are special syringes that are sold by a few suppliers, Jett and H&M Racing, but I am wondering if I need one? Will a regular big syringe do the trick?
2. Is there a special procedure for filling the tank?
3. Is there any advise on what not to do to avoid damaging them.
Al
I am new to racing, actually just getting started, and I see that most use bubbleless bladder tanks in their planes. I have a couple of questions regarding their use.
1. I see that there are special syringes that are sold by a few suppliers, Jett and H&M Racing, but I am wondering if I need one? Will a regular big syringe do the trick?
2. Is there a special procedure for filling the tank?
3. Is there any advise on what not to do to avoid damaging them.
Al
02-28-2006, 07:59 AM
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RE: Bladder Fuel Tanks
1) There is nothing special about the syringes you mentioned other than the fact that Jett and H&M has them available. Any syringe will do as long as it is fuel proof and a piece of fuel tubing can be attached to it without continually blowing off.
2) the basic procedure is to completely collapse the bladder by sucking every thing out using the syringe. Then, without allowing any air to re-enter fill the bladder with fuel.
All filling and emptying is done through the fuel feed line. How this is done is determined by the size of the syringe. Ideally the syringe should be twice the tank capacity. So, into the syringe put enough fuel to fill the tank. Hook up to the tank and completely evacuate the bladder. Then refill the bladder with solid fuel taking care to not allow bubbles to enter. When filled pinch the fuel line and remove the syringe. hook up the fuel line to the engine and leave pinched until ready to start. The emptiness or fullness of the tank can be felt by resistance when pulling or pushing on the syringe. When the tank is full pull back a bit on the syringe, do not leave the system under pressure. If you do the engine will be flooded when the pinch is removed.
If a small syringe is used then the line must be pinched every time the syringed is removed, to prevent unwanted air from entering.
3) On some of the older Tettra tanks the metal pressure fitting sometimes caused a very small tear in the bladder. There is now a piece of tubing over the end to prevent this. Apart from the usual precautions taken with fuel tank installation and care there is not much else that can be done.
Ed S
2) the basic procedure is to completely collapse the bladder by sucking every thing out using the syringe. Then, without allowing any air to re-enter fill the bladder with fuel.
All filling and emptying is done through the fuel feed line. How this is done is determined by the size of the syringe. Ideally the syringe should be twice the tank capacity. So, into the syringe put enough fuel to fill the tank. Hook up to the tank and completely evacuate the bladder. Then refill the bladder with solid fuel taking care to not allow bubbles to enter. When filled pinch the fuel line and remove the syringe. hook up the fuel line to the engine and leave pinched until ready to start. The emptiness or fullness of the tank can be felt by resistance when pulling or pushing on the syringe. When the tank is full pull back a bit on the syringe, do not leave the system under pressure. If you do the engine will be flooded when the pinch is removed.
If a small syringe is used then the line must be pinched every time the syringed is removed, to prevent unwanted air from entering.
3) On some of the older Tettra tanks the metal pressure fitting sometimes caused a very small tear in the bladder. There is now a piece of tubing over the end to prevent this. Apart from the usual precautions taken with fuel tank installation and care there is not much else that can be done.
Ed S
02-28-2006, 12:13 PM
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RE: Bladder Fuel Tanks
Umdadum:
Have used both Tetra and Jett tanks. Like the tetra tank, seems tougher, plug design is superior. Frequently remove the bladder and use them as a conventinal tank, never any leaks, or plug popping out. Lost a wonderful Hanson "Runarround" from a tank failure. For racilng and general convenience, I use the Jett tank. When filled, the jett tank does not seem to produce as much pressure. Jett uses a high streingth plastic bladder that I first thaught would be a reliability problem. After several years of use, they have proved to be rugged and reliable in the long run. ENJOY
Have used both Tetra and Jett tanks. Like the tetra tank, seems tougher, plug design is superior. Frequently remove the bladder and use them as a conventinal tank, never any leaks, or plug popping out. Lost a wonderful Hanson "Runarround" from a tank failure. For racilng and general convenience, I use the Jett tank. When filled, the jett tank does not seem to produce as much pressure. Jett uses a high streingth plastic bladder that I first thaught would be a reliability problem. After several years of use, they have proved to be rugged and reliable in the long run. ENJOY
