Problem with UAT tank. how to correctly set up fuel system
02-06-2013 | 07:11 AM
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From: Lanark, UNITED KINGDOM
Problem with UAT tank. how to correctly set up fuel system
Hi all,
I would appreciate some help and advice.
I tested my JetsMunt VT80 for the first time and wow! what a great turbine.
I primed the fuel line and the turbine started without any problems. The turbine was running for a short while until I noticed a lot of air bubbles, so I shut the turbine and let cool down.
I noticed the UAT tank was only half full (or empty
and was not filled up by the main tank.
I don't understand this as I fill the main tank through the UAT tank.
My setup is as follows:
Main tank has a vent tube (exiting through the bottom of fuselage) and a tube to the UAT tank.
UAT tank has a tube to the pump and a filler plus the tube from main tank
When I fill the tank I see that the UAT is filled up to the top and then that main tank gets filled. I have no air in the system.
As I mentioned I started the turbine and the turbine was running until the UAT tank was down to half full and then bubbles appeared (probably that is where the clunk sits)
Maybe I am missing here something stupid but why is the fuel not drawing from the main tank to the UAT? The main tank is filled through that tube.
I hope you understand my problem. Sorry if I can't explain it better.
Any advice and help would be appreciated as usual.
Ulrich
I would appreciate some help and advice.
I tested my JetsMunt VT80 for the first time and wow! what a great turbine.
I primed the fuel line and the turbine started without any problems. The turbine was running for a short while until I noticed a lot of air bubbles, so I shut the turbine and let cool down.
I noticed the UAT tank was only half full (or empty
and was not filled up by the main tank.I don't understand this as I fill the main tank through the UAT tank.
My setup is as follows:
Main tank has a vent tube (exiting through the bottom of fuselage) and a tube to the UAT tank.
UAT tank has a tube to the pump and a filler plus the tube from main tank
When I fill the tank I see that the UAT is filled up to the top and then that main tank gets filled. I have no air in the system.
As I mentioned I started the turbine and the turbine was running until the UAT tank was down to half full and then bubbles appeared (probably that is where the clunk sits)
Maybe I am missing here something stupid but why is the fuel not drawing from the main tank to the UAT? The main tank is filled through that tube.
I hope you understand my problem. Sorry if I can't explain it better.
Any advice and help would be appreciated as usual.
Ulrich
02-06-2013 | 07:18 AM
#2
RE: Problem with UAT tank. how to correctly set up fuel system
Hi Ulrich
For straters try these:
1 - Do not use a screw in the fuel fill line. Threads will allow air to get in.
2 - Change the tygon tubing for PU. DO Not use tygon pluged in Festos
3 - Change the Festo filter. They tend to brake and let air in. Keep using the filter and manual valve in the pressure side.
4 - Make sure there are no restrictions and filter in the clunk
Regards
Nuno
For straters try these:
1 - Do not use a screw in the fuel fill line. Threads will allow air to get in.
2 - Change the tygon tubing for PU. DO Not use tygon pluged in Festos
3 - Change the Festo filter. They tend to brake and let air in. Keep using the filter and manual valve in the pressure side.
4 - Make sure there are no restrictions and filter in the clunk
Regards
Nuno
02-06-2013 | 07:25 AM
#3
RE: Problem with UAT tank. how to correctly set up fuel system
Hi Uli,
Welcome to the world of jets! Your CAT (its not a UAT) is drawing air in somewhere. The first thing to check is the cable ties round the black tube between the main tank and the CAT. These are a bad idea as there can be a small gap where the ends of the tie meet which can allow air to be drawn in between the OD of the solid tube and the ID of the flex tube. Replace these (and I would do the outlet side of the CAT too) with stainless tie wire wrapped twice round the tube before twisting off.
Next thing to check is your clunk and clunk line inside the main tank. Is it a felt clunk? There is no problem with these provided they are clean and you use well filtered kero (fit a couple of filters in your fill line from your kero bottle outside the model) but if they get dirty they clog and the pressure drop across them will accentuate any air leakage into the clunk tube and the tubing from the main tank to the CAT.
Lastly I would check with Marc at GBR Jets that it is OK to mount the CAT vertically. It may be that your air margin is reduced by doing this as the pleated element in the CAT may uncover sooner. Marc will let you know.
Also I wouldn't personally have a shutoff valve on the suction side of my pump. This is another source of air into your fuel system but it isn't causing the air in the CAT. I would re-fit it on the pressure side of the pump - but you must remember to open it before starting!!!
Hope this helps.
Malcolm
Welcome to the world of jets! Your CAT (its not a UAT) is drawing air in somewhere. The first thing to check is the cable ties round the black tube between the main tank and the CAT. These are a bad idea as there can be a small gap where the ends of the tie meet which can allow air to be drawn in between the OD of the solid tube and the ID of the flex tube. Replace these (and I would do the outlet side of the CAT too) with stainless tie wire wrapped twice round the tube before twisting off.
Next thing to check is your clunk and clunk line inside the main tank. Is it a felt clunk? There is no problem with these provided they are clean and you use well filtered kero (fit a couple of filters in your fill line from your kero bottle outside the model) but if they get dirty they clog and the pressure drop across them will accentuate any air leakage into the clunk tube and the tubing from the main tank to the CAT.
Lastly I would check with Marc at GBR Jets that it is OK to mount the CAT vertically. It may be that your air margin is reduced by doing this as the pleated element in the CAT may uncover sooner. Marc will let you know.
Also I wouldn't personally have a shutoff valve on the suction side of my pump. This is another source of air into your fuel system but it isn't causing the air in the CAT. I would re-fit it on the pressure side of the pump - but you must remember to open it before starting!!!
Hope this helps.
Malcolm
02-06-2013 | 07:46 AM
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From: Lanark, UNITED KINGDOM
RE: Problem with UAT tank. how to correctly set up fuel system
Hi Malcolm, Hi Nuno
thanks for your advice. I really appreciate it.
With regards to the shut off valve.
I consulted several forums and people were discussing where to put the shut off valve - on the suction side or the pressure side of the pump.
Opinions are quite divided between the two. I decided to put it on the suction side as on the pressure side I am not sure how much pressure the pump would generate in the case of shutting that valve.
I only know I don't want to run the turbine without a shut off valve.
With regards to the CAT tank.
I thought it is an UAT tank. Anyway, the manual actually states that you should (if possibly) mount the CAT vertically as it makes sure that no air is in the tank.
The screw in the fill line I will definitely replace.
The clunk in the main tank is kind of ceramic material but was recommended for turbine use.
I will also replace that black tube from the main tank.
I am sure I will get the problem sorted. Must be a simple plumbing problem.
Thanks again for your help.
Ulrich
PS: Malcolm, would it be OK if I come over to your place and you could have a look. Just would make me feel better to have it checked out before the maiden.
thanks for your advice. I really appreciate it.
With regards to the shut off valve.
I consulted several forums and people were discussing where to put the shut off valve - on the suction side or the pressure side of the pump.
Opinions are quite divided between the two. I decided to put it on the suction side as on the pressure side I am not sure how much pressure the pump would generate in the case of shutting that valve.
I only know I don't want to run the turbine without a shut off valve.
With regards to the CAT tank.
I thought it is an UAT tank. Anyway, the manual actually states that you should (if possibly) mount the CAT vertically as it makes sure that no air is in the tank.
The screw in the fill line I will definitely replace.
The clunk in the main tank is kind of ceramic material but was recommended for turbine use.
I will also replace that black tube from the main tank.
I am sure I will get the problem sorted. Must be a simple plumbing problem.
Thanks again for your help.
Ulrich
PS: Malcolm, would it be OK if I come over to your place and you could have a look. Just would make me feel better to have it checked out before the maiden.
02-06-2013 | 07:50 AM
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From: San Juan, , PUERTO RICO (USA)
RE: Problem with UAT tank. how to correctly set up fuel system
I'm using a VT80 in a PST Reaction and NOT using UAT. Flies excellent
and no problems with bubbling. Had 3 flights this weekend without
troubles.
E.N.T.
and no problems with bubbling. Had 3 flights this weekend without
troubles.
E.N.T.
02-06-2013 | 07:56 AM
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From: Lanark, UNITED KINGDOM
RE: Problem with UAT tank. how to correctly set up fuel system
Hi E.N.T
I was actually thinking the same. Is it really necessary to fit an UAT?
I guess opinions are divided and everyone has it's preferences.
Ulrich
I was actually thinking the same. Is it really necessary to fit an UAT?
I guess opinions are divided and everyone has it's preferences.
Ulrich
02-06-2013 | 08:56 AM
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From: Lanark, UNITED KINGDOM
RE: Problem with UAT tank. how to correctly set up fuel system
Hi all
that was a quick and easy fix. I think I got the problem sorted.
It was indeed the screw in the filler line and I replaced it with a short rod.
I filled up the tank and started the pump running the fuel into a canister. After several minutes still no air in the line, CAT full up to the top.
Great result. Thanks again for your help.
Ulrich
that was a quick and easy fix. I think I got the problem sorted.
It was indeed the screw in the filler line and I replaced it with a short rod.
I filled up the tank and started the pump running the fuel into a canister. After several minutes still no air in the line, CAT full up to the top.
Great result. Thanks again for your help.
Ulrich
02-06-2013 | 11:20 AM
#11
RE: Problem with UAT tank. how to correctly set up fuel system
Hi Uli,
Glad you got it sorted but I'm happy for you to pop over and have it looked at before the maiden.
I'm going on holiday next week, back on 25th shoot me a pm or an email and we'll arrange it after then.
Cheers,
Malcolm
Glad you got it sorted but I'm happy for you to pop over and have it looked at before the maiden.
I'm going on holiday next week, back on 25th shoot me a pm or an email and we'll arrange it after then.
Cheers,
Malcolm
02-06-2013 | 01:51 PM
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From: coral springs,
FL
RE: Problem with UAT tank. how to correctly set up fuel system
ORIGINAL: uixkes
Hi all,
I would appreciate some help and advice.
I tested my JetsMunt VT80 for the first time and wow! what a great turbine.
I primed the fuel line and the turbine started without any problems. The turbine was running for a short while until I noticed a lot of air bubbles, so I shut the turbine and let cool down.
I noticed the UAT tank was only half full (or empty and was not filled up by the main tank.
I don't understand this as I fill the main tank through the UAT tank.
My setup is as follows:
Main tank has a vent tube (exiting through the bottom of fuselage) and a tube to the UAT tank.
UAT tank has a tube to the pump and a filler plus the tube from main tank
When I fill the tank I see that the UAT is filled up to the top and then that main tank gets filled. I have no air in the system.
As I mentioned I started the turbine and the turbine was running until the UAT tank was down to half full and then bubbles appeared (probably that is where the clunk sits)
Maybe I am missing here something stupid but why is the fuel not drawing from the main tank to the UAT? The main tank is filled through that tube.
I hope you understand my problem. Sorry if I can't explain it better.
Any advice and help would be appreciated as usual.
Ulrich
Hi all,
I would appreciate some help and advice.
I tested my JetsMunt VT80 for the first time and wow! what a great turbine.
I primed the fuel line and the turbine started without any problems. The turbine was running for a short while until I noticed a lot of air bubbles, so I shut the turbine and let cool down.
I noticed the UAT tank was only half full (or empty
and was not filled up by the main tank.I don't understand this as I fill the main tank through the UAT tank.
My setup is as follows:
Main tank has a vent tube (exiting through the bottom of fuselage) and a tube to the UAT tank.
UAT tank has a tube to the pump and a filler plus the tube from main tank
When I fill the tank I see that the UAT is filled up to the top and then that main tank gets filled. I have no air in the system.
As I mentioned I started the turbine and the turbine was running until the UAT tank was down to half full and then bubbles appeared (probably that is where the clunk sits)
Maybe I am missing here something stupid but why is the fuel not drawing from the main tank to the UAT? The main tank is filled through that tube.
I hope you understand my problem. Sorry if I can't explain it better.
Any advice and help would be appreciated as usual.
Ulrich
02-06-2013 | 02:25 PM
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From: Lanark, UNITED KINGDOM
RE: Problem with UAT tank. how to correctly set up fuel system
I thought all these air trap tanks are called UAT. Did not know it's a trade name of BVM.
Thanks again for your help.
Ulrich
Thanks again for your help.
Ulrich
02-06-2013 | 07:00 PM
#14
RE: Problem with UAT tank. how to correctly set up fuel system
ORIGINAL: uixkes
Hi E.N.T
I was actually thinking the same. Is it really necessary to fit an UAT?
I guess opinions are divided and everyone has it's preferences.
Ulrich
Hi E.N.T
I was actually thinking the same. Is it really necessary to fit an UAT?
I guess opinions are divided and everyone has it's preferences.
Ulrich
How good is RCU?? Almost instance response to help you trouble shoot your fuel system.
I agree that a UAT or a CAT is not always necessary, and a lot of people successfully operate a turbine with out one.
However, look at it this way. If you did not have a CAT fitted, you may never have picked up the air leak that you already had. So your CAT has already done a sterling job for you.
I am in favour of air traps. I make it a habit to check my UAT after every flight. If the air bubble is excessively large, this is a sign that a air leak may have developed up stream. They also make a great final filter..
Roger
02-07-2013 | 02:23 AM
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From: farnborough, , UNITED KINGDOM
RE: Problem with UAT tank. how to correctly set up fuel system
I friend of mine had your type bubble trap in an airplane that constantly would flame out due to air.
The CAT which is a product designed to help prevent air entering the fuel feed to the turbine (via the pump) has been successfully used for the last 12 months on the NASA/Boeing joint project - X48C. The units were tested to the limits before they were approved for use in a multi-million $ project and I am certain they would have not used them if there was a chance they were no good!
Whilst there is always a chance products do not work for all there are some real important things that must be done to ensure any fuel related products stand a good chance of delivering 100% reliability -
USE QUALITY CORRECT BORE TUBING
SECURITY WIRE ALL FITTINGS - DO NOT USE CABLE TIES (as the name implies they are for use with cable not fuel line)
AVOID EXTRA FILTERS IN LINE, VALVES OR RESTRICTIONS (these will restrict fuel flow and that's not a good thing)
MOUNT CORRECTLY (as per manufacturers spec)
USE CORRECT FITTINGS TO SEAL PIPES AND FITTINGS
I personally make and test EVERY CAT to 30-40psi, which is more than the pressure in most car tyres so unless the unit has been damaged there is NO way it will leak air, if air is getting into it then its coming from a connection elsewhere on the fuel system (or via cavitation)
If you wish to check some of the test data on a range of UAT products including the CAT have a look at this very in depth article about 'all things' related to setting up a reliable full system..
[link]http://www.ultimate-jets.net/blogs/fuel-system-for-jets-considerations[/link]
marcs
02-07-2013 | 02:44 AM
#16
RE: Problem with UAT tank. how to correctly set up fuel system
Marc
I'm not getting at your product at all...but a Boeing X48C's fuel demands are completely different from an aerobatic jet...or even a large smooth scale one.
Smaller turbine models put a huge demand on the supply tank, the pickup and fuel moves around a lot more and its this supply (if the filler is not sealed) that can introduce the air.
Dave
I'm not getting at your product at all...but a Boeing X48C's fuel demands are completely different from an aerobatic jet...or even a large smooth scale one.
Smaller turbine models put a huge demand on the supply tank, the pickup and fuel moves around a lot more and its this supply (if the filler is not sealed) that can introduce the air.
Dave
02-07-2013 | 03:01 AM
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From: farnborough, , UNITED KINGDOM
RE: Problem with UAT tank. how to correctly set up fuel system
Dave whilst you comments are valid there is still the point here that the product works in situations where high demand is made (the ID on the feed to and outlet from the X48C's CAT's is 10mm!) on parts, fuel delivery and the concept. Manufacture and design of the CAT is tested at the highest possible levels, which I hope gives extra endorsement to those looking to spend their hard earned cash on accessories to keep their expensive jets in the air.
marcs
marcs
02-07-2013 | 03:33 AM
#18
RE: Problem with UAT tank. how to correctly set up fuel system
ORIGINAL: marc s
I would be interested to understand why this happened, as in essence the method of what my CAT product does and the BVM UAT are very similar so why one works and the other does not is somewhat baffling!
The CAT which is a product designed to help prevent air entering the fuel feed to the turbine (via the pump) has been successfully used for the last 12 months on the NASA/Boeing joint project - X48C. The units were tested to the limits before they were approved for use in a multi-million $ project and I am certain they would have not used them if there was a chance they were no good!
Whilst there is always a chance products do not work for all there are some real important things that must be done to ensure any fuel related products stand a good chance of delivering 100% reliability -
USE QUALITY CORRECT BORE TUBING
SECURITY WIRE ALL FITTINGS - DO NOT USE CABLE TIES (as the name implies they are for use with cable not fuel line)
AVOID EXTRA FILTERS IN LINE, VALVES OR RESTRICTIONS (these will restrict fuel flow and that's not a good thing)
MOUNT CORRECTLY (as per manufacturers spec)
USE CORRECT FITTINGS TO SEAL PIPES AND FITTINGS
I personally make and test EVERY CAT to 30-40psi, which is more than the pressure in most car tyres so unless the unit has been damaged there is NO way it will leak air, if air is getting into it then its coming from a connection elsewhere on the fuel system (or via cavitation)
If you wish to check some of the test data on a range of UAT products including the CAT have a look at this very in depth article about 'all things' related to setting up a reliable full system..
[link]http://www.ultimate-jets.net/blogs/fuel-system-for-jets-considerations[/link]
marcs
I friend of mine had your type bubble trap in an airplane that constantly would flame out due to air.
The CAT which is a product designed to help prevent air entering the fuel feed to the turbine (via the pump) has been successfully used for the last 12 months on the NASA/Boeing joint project - X48C. The units were tested to the limits before they were approved for use in a multi-million $ project and I am certain they would have not used them if there was a chance they were no good!
Whilst there is always a chance products do not work for all there are some real important things that must be done to ensure any fuel related products stand a good chance of delivering 100% reliability -
USE QUALITY CORRECT BORE TUBING
SECURITY WIRE ALL FITTINGS - DO NOT USE CABLE TIES (as the name implies they are for use with cable not fuel line)
AVOID EXTRA FILTERS IN LINE, VALVES OR RESTRICTIONS (these will restrict fuel flow and that's not a good thing)
MOUNT CORRECTLY (as per manufacturers spec)
USE CORRECT FITTINGS TO SEAL PIPES AND FITTINGS
I personally make and test EVERY CAT to 30-40psi, which is more than the pressure in most car tyres so unless the unit has been damaged there is NO way it will leak air, if air is getting into it then its coming from a connection elsewhere on the fuel system (or via cavitation)
If you wish to check some of the test data on a range of UAT products including the CAT have a look at this very in depth article about 'all things' related to setting up a reliable full system..
[link]http://www.ultimate-jets.net/blogs/fuel-system-for-jets-considerations[/link]
marcs
Hey there Marc,
Want to thank you so much for that link to the article on UAT/CAT products.......
Extremely informative my friend.
Isn't it great how folks from all parts of the globe can share knowledge and help each other get the most out of this hobby!
Bill
02-07-2013 | 09:14 AM
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From: Hamilton,
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RE: Problem with UAT tank. how to correctly set up fuel system
Marc
One thing to mention. You test each and every CAT to 30-40 psi for leaks but...they operate under suction. The difference between suction and pressure could result in different results.
I only mention this because I work for a plastic closure company and find big differences between testing for pressurized product and product that may draw a vacuum in regards to leak testing.
One thing to mention. You test each and every CAT to 30-40 psi for leaks but...they operate under suction. The difference between suction and pressure could result in different results.
I only mention this because I work for a plastic closure company and find big differences between testing for pressurized product and product that may draw a vacuum in regards to leak testing.
02-07-2013 | 09:21 AM
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From: Hamilton,
ON, CANADA
RE: Problem with UAT tank. how to correctly set up fuel system
Have you ever seen posters that ask you to pick out all of the safety hazards. They are usually funny to look at and interesting to pick out all of the unsafe hazards.
This photo kind of reminds me of them. You can see multiple no-no's for fueling a jet.
Tie wraps on connections
no safety wire
Threaded bolt as a stopper.
Festo on the suction side
You can even add items like ensuring all connections are in good condition. I have seen where someone has used a knife to cut off an old fuel line leaving a score line in the barbed connector. The score line works like a channel for a leak to occur.
Marc's comments above are right on the money!! Good points for doing a proper fuel system install.
This photo kind of reminds me of them. You can see multiple no-no's for fueling a jet.
Tie wraps on connections
no safety wire
Threaded bolt as a stopper.
Festo on the suction side
You can even add items like ensuring all connections are in good condition. I have seen where someone has used a knife to cut off an old fuel line leaving a score line in the barbed connector. The score line works like a channel for a leak to occur.
Marc's comments above are right on the money!! Good points for doing a proper fuel system install.
02-07-2013 | 10:27 AM
#24
RE: Problem with UAT tank. how to correctly set up fuel system
I wish people would stop rubbishing Festo QS fittings in suction applications.
Actual operating pressure range is -0.95 to 14 bar see here page 9
https://www.festo.com/cat/en-gb_gb/d...F/EN/QS_EN.PDF
Absolute vacuum is around -1.07 bar!
Malcolm
Actual operating pressure range is -0.95 to 14 bar see here page 9
https://www.festo.com/cat/en-gb_gb/d...F/EN/QS_EN.PDF
Absolute vacuum is around -1.07 bar!
Malcolm
02-07-2013 | 11:47 AM
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From: Lanark, UNITED KINGDOM
RE: Problem with UAT tank. how to correctly set up fuel system
just wanted to say that I had the turbine running again and with absolute no problems at all.
I can't see any air bubbles at all and the only thing I changed was the screw in the filler line.
Nevertheless I am taking on board all the advice and will replace the tie wraps although I can pull very hard without the tubes to come off. (and I mean I can pull very hard)
With regards to the shut off valve.
As I mentioned before I was consulting several forums and people are having lively discussions of where to put the valve.
I don't like the valve to be on the pressure side of the pump. If I shut that valve will the pump not create a high pressure on the tubes?
Finally, what is wrong with a Festo valve? Why should a JetCat valve be better?
Thanks again for all the help and advice. I am really enjoying my new venture into turbines a lot.
Ulrich
I can't see any air bubbles at all and the only thing I changed was the screw in the filler line.
Nevertheless I am taking on board all the advice and will replace the tie wraps although I can pull very hard without the tubes to come off. (and I mean I can pull very hard)
With regards to the shut off valve.
As I mentioned before I was consulting several forums and people are having lively discussions of where to put the valve.
I don't like the valve to be on the pressure side of the pump. If I shut that valve will the pump not create a high pressure on the tubes?
Finally, what is wrong with a Festo valve? Why should a JetCat valve be better?
Thanks again for all the help and advice. I am really enjoying my new venture into turbines a lot.
Ulrich
