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What Fuel Line to use

vonjet

Well Known Member
What is the best flexible fuel line to use? I need some line without fittings I need 1/4" line that will go on 1/4" aluminum lines with hose clamps.
 
What are you using it for?

I'm going to go ahead and assume that this isn't for actual fuel use on an airplane (or even a lawn mower). If this is for actual fuel use, there are several issues with your config, but let's assume you are wanting to do something else with 1/4" aluminum line joined to flexible hose.

Depending on the content of the line, you could use silicone tubing from Spruce. I used it in my pitot system to join aluminum hard line (pitot heat sink) to nyloseal tubing. Worked great.

If you are thinking of some other fluid that is flammable and/or inside of the cabin, you may want to reconsider the transition and hose clamp idea. There are better choices that are not expensive.
 
yes its for fuel.

This is for fuel. I should mention its for a Lancair. The fuel transfer from the wings to the Header tank, which is the main tank. The plans have always called for fuel lines to attach to the header tank feeds with hose clamps. There is about 2 feet of this line in the cockpit. Its a stupid design but I dont know how else to do it. The aluminum lines coming out of my header tank are too short to put a flare and b nut on them. Unless I can have a fitting welded on to the aluminum tubing.
 
Hose clamps work OK

I can only burned at the stake once so I might as well..:)

In my old Zenair Zodiac I had hose clamps everywhere..not one of them ever failed in 500 hours and the new oners have not reported any problems..The Yaks from Russia are also covered in hose clamps..They work Ok but they are not as bullet proof as what we normally use.

I would not use them for high pressure but up to 10psi I am comfortable with them.

Here is what i would do..You have a 1/4 or 3/8ths piece of tube coming out of the header tank right?

Go to the hardware store and buy a copper compression fitting of the same size.

Slip the cap end over the tube towards the tank and tighten the fitting.

remove the fitting and the compression ring is still firmly attached to the tube.

Now take a Dremel or whatever and cut the cap lengthwise so you can remove it without damaging the tube or tank...quite easy.

Slip the rubber hose (yes from your autoparts store) onto the tube and over the compression fitting...Use a hose clamp in the tank side of the compression ring.

The tube will never pull off because the hose clamp won't slide over the bump that is the compression ring.

Use firesleeve over the rubber hose and hose clamp.

There you go a very solid connection...And of course someone will start whining about how the copper ring and the alu tube are not compatible..well use a little grease and it will be air tight. I used this method for 500 hours and they all looked perfect at every annual.

Frank
 
OH

I was talking about doing this on the HOT side of the firewall..for the other side delete the firesleeve.

If you want to run solid 3003 tubing then just use my method to connect the ends.

really it will work fine...If your worried about an accident i would argue this method is probably less likely to fail than a flare fitting.

Lets hope we never have to find out though..:)
 
snipped
Go to the hardware store and buy a copper compression fitting of the same size.

Slip the cap end over the tube towards the tank and tighten the fitting.

remove the fitting and the compression ring is still firmly attached to the tube.

Now take a Dremel or whatever and cut the cap lengthwise so you can remove it without damaging the tube or tank...quite easy.

snipped

Frank

The proper name for the round barrel which will stay on your fuel line (as advised by Frank) is a ferrule. Might as well use the proper terminology for this stuff. Saves embarrassment at Ace Hardware or Home Depot. :D

If you plan to use rubber fuel line, I would suggest asking for rubber hose rated for fuel injection use (good for 60 psi). You don't need the pressure rating, but my experience (owner of an auto repair shop) is that the fuel injection hose lasts MUCH longer than the cheaper "carburetor" (ie low pressure) hose. The carburetor hose tends to dry out after a few years exposure to fuel. It then starts to crack (leaking fuel in the cabin is not something to be desired). You can also increase the security of your hose installation by using two instead of one hose clamp, at each joint.
Charlie Kuss
 
Hehe

Try being into this stuff AND being English..I've gotten past my embarrassment a long time ago..:)

Hose clamps are called Jubilee clips where i come from would you believe..

Frank
 
Try being into this stuff AND being English..I've gotten past my embarrassment a long time ago..:)

Hose clamps are called Jubilee clips where i come from would you believe..

Frank

Jubilee clips? That's about as descriptive as OETIKER. :) ala, Hans Oetiker mechanical workshop in Horgen, Switzerland, 1942.

I don't know about Jubilee clips but the later are about as bullet proof as any clamp can be with high pressure hose and injection systems. I am using them with Airtex pumps because the pumps do not have AN fittings but 5.16" hose attachments.

There are millions of autos out there with high pressure systems using this technology. They are very reliable. I changed the hose after 4 years but it probably was a waste of time. The hose seemed very serviceable and the clamps had to be destroyed to get them off.
 
Ferrule or flare

Rather than use a Ferrule the plans called for adding a slight flare to the tube then slip the hose over this flare. The previous builder did this. Should I expect this to be as good as a ferrule and slide the hose over it and use 2 hose clamps to secure?


Thanks for all the help.

Bryan
 
Rather than use a Ferrule the plans called for adding a slight flare to the tube then slip the hose over this flare. The previous builder did this. Should I expect this to be as good as a ferrule and slide the hose over it and use 2 hose clamps to secure?


Thanks for all the help.

Bryan

There is a better way to go from hose to tube. MSC has a AN6 37 degree fitting with a barbed hose attachment. If you are interested, I can look up the part number, I've got it somewhere in my stuff. I bought several a few years back.
 
If you are worried about the ferrule changing position or moving for some reason (I dont' forsee it happening, once it is locked in place they tend to stay there) there is a tool you can buy that will form a bead on the tubing. It is for sale from Aircraft Tool Supply http://www.aircraft-tool.com/shop/d...&ReturnPage=/shop/search_result.aspx?PageNo=1 for $156. You may be able to find one from a local shop in your area. If the tubing is out of the airplane you can take it to them and they will probably even bead it for you.
 
Certified airplanes use hose clamps all the time for low pressure fuel. Heck thats the ONLY way to hook up a bladder! I suggest Stratoflex 193 hose for this application...
 
More than one way to skin a cat

Rather than use a Ferrule the plans called for adding a slight flare to the tube then slip the hose over this flare. The previous builder did this. Should I expect this to be as good as a ferrule and slide the hose over it and use 2 hose clamps to secure?


Thanks for all the help.

Bryan
Bryan,
Yes, a "slight" flare at the tip will help. The trick is to make a "minimal" flare. (about 1/64" high) Doing a slight double flare would ensure that you didn't have a sharp edge on the end of the tube. Make sure you lube the hose with oil prior to installing it over the flare. Use two clamps on the joint. Place one of the clamps right behind the area of the flare.
David Domeier's suggestion of using a "hose to flare connector will also work (but costs more) if you had room to flare the tubing, which you stated earlier that you did not. The barbs on this fitting will ensure that the clamped hose doesn't come off the fitting.
Personally, I like Frank's idea of the ferrule better. The ferrule has a sloped surface at both ends, so there is no chance of "skiving" the inside of the hose. Skiving means that a sharp edge on the tubing cuts the inside diameter of the hose. This cut section could come off immediately or later. If it lodges between critical parts of the fuel system (like the needle and seat of a carburetor), you may end up with an off airport landing, or worse.
Another lister mentioned the "proper" way to secure a tube to clamped hose joint, with a beading tool. That's a high dollar tool for one builder to buy. Perhaps you could convince your local EAA Chapter to buy one and add it to their tool lending library?
Charlie Kuss
 
Rather than use a Ferrule the plans called for adding a slight flare to the tube then slip the hose over this flare. The previous builder did this. Should I expect this to be as good as a ferrule and slide the hose over it and use 2 hose clamps to secure?
Thanks for all the help.
Bryan
Although this method will work, I don't recommend it. The edge of the flare will continually "work" on the inside of the hose. The "ferrule" is a better idea, in my opinion.
 
Certified airplanes use hose clamps all the time for low pressure fuel. Heck thats the ONLY way to hook up a bladder! I suggest Stratoflex 193 hose for this application...

Stephen,
Stratoflex 193 is a good choice IF he never runs unleaded auto fuel. 193 is made from Buna N (aka Nitrile) rubber. See

http://www.sacskyranch.com/h_193.htm

It's not the best choice for use with automotive or unleaded fuels. If you plan on 100 LL going away or plan to use auto fuels, automotive fuel injection hose is a better choice. Buy name brand hose and you won't be disappointed. Gates and Bando are the top brands. See

http://www.gates.com/australia/brochure.cfm?brochure=7460&location_id=11312

Note that the Gates hose even handles ethanol, which hopefully will never get into your fuel tanks. Ethanol is a real problem for aircraft fuel systems and fiberglass fuel tanks.

Most quality auto parts stores will sell this by the foot. "Quality" means you can forget Advance Auto, Pep Boys, etc. unless they can get you the name brand stuff. I would not trust what comes off the spool at most parts stores.
Charlie Kuss
 
Question

Certified airplanes use hose clamps all the time for low pressure fuel. Heck thats the ONLY way to hook up a bladder! I suggest Stratoflex 193 hose for this application...

Stephen,
I'm sure that Flourosilicone, and Viton rubber hoses are available through aviation fluid sources. Might you know what the product listings for these might be?? Teflon lined hoses will carry nearly any fluid, but are not as flexible as flourosilicone or Viton.

Charlie Kuss
 
Ferules

This method is very slick and cheap. I will defer to using the high pressure hose, although I have been using the cheap stuff for a long time, mainly because I usually replaced it every other year or so.

If this is a "fit and forget" installation then a high pressure flex hose is probably a good idea.

I would not flare the end becuase of the potential for the sharp edge as described above.

Frank
 
There is nothing else besides the 193 that works as well for that particular application. The 156 would be the next better thing, which has steel braid, so it doesn't fit over the ferrule very well.

I would never recommend an auto hose for any aviation application, and if I saw one on an airplane, I'd see it replaced before I signed it off.
 
There is nothing else besides the 193 that works as well for that particular application. The 156 would be the next better thing, which has steel braid, so it doesn't fit over the ferrule very well.

I would never recommend an auto hose for any aviation application, and if I saw one on an airplane, I'd see it replaced before I signed it off.

As has been stated, quality high pressure hose from the auto industry is about as bullet proof as fuel hose can be provided it is properly connected. The stuff lasts a long time and you can run just about anything through it.

I have a hard time being married forever without qualification to anything "aviation - government approved".

In a previous airplane, certified Aeroquip hose failed in that when under pressure (a mere 7psi of 100LL) it leaked like a sieve right through the entire body of the hose. I was lucky not to have had an in-flight fire. Yes, the stuff was recalled - but it had that stamp of approval which should have given you that warm fuzzy "its OK" feeling but in fact did not. This stuff was used on many certified airplanes. Same can be said for carb floats. They have been sinking for at least 40 years - I had one in N6930G a C-150 in the early 70's - and the "approved" material still is not bullet proof.

The notion that anything from the auto industry is no good in an airplane does not hold water. Many autos today will run 100,000 miles without service beyond fuel and lubrication because the parts going into these vehicles are of very high quality. Some of that quality can be transferred to an airplane and is everyday in experimental machines. Where do you think these great Nippon-Denso alternators come from?

Much of general aviation is stuck in a very old rut with very old "approved" stuff. I won't hang my hat on some of it.
 
I totally agree

Auto stuff is very high quality these days and perfectly acceptable on an airplane.

Frank
 
I know is CAN be just as high quality, and i've put some auto parts on RV's myself. BUT how can it be recommended if the specs aren't tracable... and when it's seen on an airplane, how do you know what it's history is... what is the shelf life? How often do you replace it? An installation like the Lancair isn't exactly an easily inspectable spot.

To many variables. I've seen fair too many auto hoses react poorly in aircraft applications to trust them at all for my airplane, or my customers. If I wouldn't fly with it, how can I recommend it to someone else? Silicone based hoses have potential, and PTFE definitely, but you are FAR more likely to find airplane hoses on my car, than car hoses on my airplane.
 
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