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fuel flow transducer location

cytoxin

cytoxin

Well Known Member
well after days of reading 50 million posts about this. ive come to the conclusion im installing the fuel flow transducer above the gascolator. however no one mentioned a doubler. looks to me the u shaped tube is gonna work harden and break if the transducer is not mounted very firmly..what did you do that made it rigid. have you inspected the amount of movement on shut down? here is where i am at.

 
Direct Mount?

William -

Why the shelf? I don't see any problem with the location, but I'd mount it right on the firewall. A little doubler on the cabin side with nutplates to make it easy to mount and service and another on the forward side to act as a stand-off for clearance for the hose-ends.
 
welll

the unit has to mount with the wires exiting out of the top. the shelf maybe somewhat obscured by the clamp but is a piece of angle bolted to a doubler plate inside similar to the sol/relay plate. the bracket at the bottom is an attempt to stiffen it up a bit. worked well but when i shake the hose in a simulated shut down the tube seems to flex and i feel will work harden it.
i know others have this set up just wondering what they did here.
 
Mounted mine between the fuel pump & gascolator on the inside. It was tight but seemed like a good place.
 
i like that spot

but i wanted it down stream of the filter/ gascolator..and it is suppossed to be level or close to it.do you have a filter installed....
 
i am at this point too. i placed mine after the gasolator as did cytoxin. I used an angle iron, and rivited it to the gasolator doubler. It is nice and rigid. The only downfall is that the bend in the tubing is a little sharper than the picture of cytoxins. However I was able to put an adel clamp on the outside of the bend to give the aluminum tubing some extra support and to minimize vibration.

Please take a look CNEJR, or maybe you have at the size of the inlet going into the transducer. It is very small!! Maybe 3/16 inch. The fuel should most certainly be filtered before it enters the transducer Just a thought.
 
Fuel flow

I came straight out of the filter (mounted on firewall) for a total of 5 inches then I made a 90 after about 2 inches. I mounted it on a heavy piece of alum angle that is attached to the firewall also.
 
William,

Mine is mounted as you did and with 84 hours on the clock, no problem, even with out the stiffener between the gascolator and the fuel flow meter.

There is a doubler on the inside of the firewall which the AA bolts through.

I would be more worried about the aluminum fitting the flex line attaches to than the "U".
 
Hi Bill.

I take it you found out that your "u" was not the source of the fuel starvation issue you had a while back. Was it the idle screw on your carb?

I have the same gascolater setup (not flying yet) and wanted to verify it wasn;t the source of your problem.

Thanks,
Scott
 
Bill,

It may already be too late but check to make sure you can still get your battery lead to the master realy. I have my sender in about the same place and I wish I had left a little more room for the large power cable. Also I have noticed that when I have the boost pump on the flow indicates several more GPM than it does with the boost off. My guess is that the pump sends pulses of fuel down the line and perhaps if the flow sensor were further down stream it would not pick up the pulses. I also added insulation on the U tube just to help keep it cool like the line running from the sensor output to the mechanical pump.

Good Luck
 
Most of the fuel instrument folks like ECI recommend flexible hoses before and after the fuel flow sensor.
Danny
 
If you got the clearance I would mount the transducer just upstream from the carb suspended in flex-line. Before the gascolator may work, but I've seen the best results from being after.

Good luck!

Matt
 
I WAS UNDER THE IMPRESSION THE FUEL FLOW TRANSDUCER HAD TO BE LOCATED BETWEEN THE ENGINE DRIVEN PUMP & THE CARB. OR FI SERVO.THE REASON BEING THAT PUMPS CAN PUSH FUEL BETTER THAN SUCKING IT.I THINK THEY ARE TRYING TO AVOID VAPOR LOCK.
 
you are correct

HROCKLEN said:
I WAS UNDER THE IMPRESSION THE FUEL FLOW TRANSDUCER HAD TO BE LOCATED BETWEEN THE ENGINE DRIVEN PUMP & THE CARB. OR FI SERVO.THE REASON BEING THAT PUMPS CAN PUSH FUEL BETTER THAN SUCKING IT.I THINK THEY ARE TRYING TO AVOID VAPOR LOCK.
Click to expand...

but they also want 6 inches of straight line before and after the transducer. to put it in the line will neccessitate a 90 deg elbow. which works good i hear. i dont want the line anchored midspan to the engine mount and the ends at the pump and carb...but ive seen some done that way.

Mathew Sharp said:
If you got the clearance I would mount the transducer just upstream from the carb suspended in flex-line. Before the gascolator may work, but I've seen the best results from being after.

Good luck!

Matt
Click to expand...
i think this would be ok except that the line is supposed to go up after leaving the transducer...if trapped air gets in the sensor it really throws off the readings. and hard to not do it with out elbows.
 
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tx_jayhawk said:
Hi Bill.

I take it you found out that your "u" was not the source of the fuel starvation issue you had a while back. Was it the idle screw on your carb?

I have the same gascolater setup (not flying yet) and wanted to verify it wasn;t the source of your problem.

Thanks,
Scott
Click to expand...
Scott,

I don't want to drift this thread so check my last post on this thread.
 
well here is the latest

i didnt want to fasten the the hose at mid span but i may have to do that.

 
whoah, aluminium tube ????

William, that looks like an aluminium fuel line that you have used at the transducer (and if it's supplied by Vans it will be cheap .032 wall no-name commercial aluminium tube ...not .035 wall aviation grade 5052-0). I've never seen a certificated aircraft with aluminium fuel line forward of the firewall (I'm not saying there isn't one, but I haven't seen it). There's probably a very good reason for that.

I don't think your transducer is in the best position but if you want to persevere with that arrangement then you might like to consider stainless tube.
 
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Carefull

Captain Avgas said:
William, that looks like an aluminium fuel line that you have used at the transducer (and if it's supplied by Vans it will be cheap .032 wall no-name commercial aluminium tube ...not .035 wall aviation grade 5052-0). I've never seen a certificated aircraft with aluminium fuel line forward of the firewall (I'm not saying there isn't one, but I haven't seen it). There's probably a very good reason for that.

I don't think your transducer is in the best position but if you want to persevere with that arrangement then you might like to consider stainless tube.
Click to expand...

Careful - Last time that U shaped fuel line was discussed on here I commented on the same thing, and got flamed out of the post!!
 
in a perfect world

JonJay said:
Careful - Last time that U shaped fuel line was discussed on here I commented on the same thing, and got flamed out of the post!!
Click to expand...

we would all use steel fittings and tube. but in the experimental world well its experimental...i however am not. that said, i think i'll put this aside for a while and work on the wires spewing forth from panel. :confused::D while i wait on my mext spruce order to arrive;) or maybe not usethe flow sender at all.
 
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cytoxin said:
we would all use steel fittings and tube. but in the experimental world well its experimental...i however am not. that said, i think i'll put this aside for a while and work on the wires spewing forth from panel. :confused::D while i wait on my mext spruce order to arrive;) or maybe not usethe flow sender at all.
Click to expand...

Dont give up ;) lots of guys doing it very successfuly.
 
cytoxin said:
or maybe not usethe flow sender at all.
Click to expand...

Put it in William....somewhere. It will unlock a large number of very important features on your engine mangement system (I'm presuming you are in fact installing an EMS...just about everyone does these days). Fuel remaining, fuel remaining at destination, MPG, current fuel flow etc could all be VERY handy in a pinch.
 
steel?

I have been watching this thread with interest and I appreciate William getting it started. I'm not not close to even installing the floscan, but I try to keep a ahead a little so I know pretty much what I'll do when I get there.

It looks like the U-tubing is one of several acceptable ways of plumbing the transducer. If using steel is the "best practice" in this case, is that something that would be special ordered or would a roll-form type bender & flaring tool work with the steel? I have the Avery bender (not the springs) and the Parker flaring tool. Would you use steel fittings also?

Keep the info & opinions coming!
 
Protective fire shielded Hoses

I believe the reason they use hose wrapped in fire shield firewall forward is to keep the fuel cooler to prevent vapor lock. Having the c aluminum tubing located there is not an issue of stress and it breaking. It is on the firewall, not the engine. All fittings on the engine MUST be steel. On the firewall they can be aluminum because there is substantually less vibration.

I have been following this thread for some time. I for one am going to install the floscan pretty much exactly as the picture that William has posted.

jarvis
 
I did mine a little different because I used the Andair gascolator. I used a piece of .063 to add a base to the top of the gascolator mount. Then with a couple of spacers, I mounted the Flo Scan Sensor. Adding a little bend to the base plate made it line up well with the fuel pump. A couple of adel clamps made it VERY solid.

I know it probably should be a U shape but I think the more important thing is smooth flow not necessarily straight flow,... we'll see. It's a pretty big loop with about 5-6 inches of almost straight line. Will cover with firesleeve later.

That also allowed me to run my primer line straight up.

Hope this helps.

Bill S
7a Ark finishing


 
Mine is mounted similarly to the previous post's picture. I have over 900 hours, no problems, and a very accurate fuel flow readings (however, mine is between the fuel servo and flow divider, so no pulsing flow from the engine pump). I wrapped the aluminum lines in fire sleeve, and since they are fastened to the firewall, I have no concerns for fatigue. I also wrapped the flow sensor in some silicone foam to insulate it from heat.
 
thnaks to all who have contributed

i feel i have a good setup going, but i will attempt to bend the line from stainless and the 5202-o alloy BB sugested... install the outlet fitting to the transducer in steel. at the present i have 4 steel fittings and a couple feet of stainless and 5202-o on the way.
got a reply from a technical source that says it fine just as it is. and a couple of PM,s as well saying the same. i will post the finished product next week when spruce gets me my stuff. in the mean while i have 2.5 weeks off to get some wiring done....:( no plans for this, just guessing right along...probally end up with swiss cheese for a firewall.
 
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well this is it

i bent the line from stainless. it was the limit of what my bender will do. then i used aluminum fittings...well this looked and felt good but i was concerned about the low torque of the aluminum nuts on the steel tube. so i ordered steel sleves and nuts. bent another u-tube and installed it with a bracket from the gascolator to the flow sensor and a doubler plate that tied to the battery box. now i have a ton of u shaped tubing laying around.







I really love having all of the electrical and fuel components so close to each other, gives me a warm fuzzy feeling:rolleyes:
 
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cytoxin said:
got a reply from a technical source that says it fine just as it is. and a couple of PM,s as well saying the same.
Click to expand...
I'm confused...

Did they say it was fine in aluminum or fine that you changed to SS?

PS. Don't forget the firesleave to keep the heat out.
 
they said

N941WR said:
I'm confused...

Did they say it was fine in aluminum or fine that you changed to SS?

PS. Don't forget the firesleave to keep the heat out.
Click to expand...

aluminum was fine. i changed after the consult.

wont forget the fire sleeve. thanks for the reminder.
 
Battery positive

William,

I have a similar install as yours, but not as high up.

Where are you routing the positive battery lead to battery contactor? It seems like your location may interfere with the "normal" routing of that lead.

Thanks,
Scott
7A FWF Plumbing
 
in the stock loction

i will install it per plans.. the picture is somewhat misleading in that regard, but there is plenty of room for it per plans.(ok maybe not plenty but enough with an adel clamp) keep in mind that because it is anchored at the end to the solenoid there is little movement of the cable.
and i have a 100$ worth of adel clamps.:mad::D
 
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fuel flow meter mounting

William, My 9a is mounted in the same area with a bracket mounted on the firewall( and a doubler ). For the "u" tube i used stainless steel after someone asked about fire resistance of soft aluminum tubing.
happy building. n815vp
 
Will rolo-flare tool handle stainless?

Someone asked above, but I didn't see an answer... Will a regular rolo-flare tool handle stainless tubing OK?
 
Rolo-Flair on Stainless

Mark Burns said:
The Parker rolo flare is not "rated" for stainless. I remember reading that somewhere.

Mark
Click to expand...

True, the Parker documentation says "Copper and Aluminum Alloys Only." Having said that, I used mine on the 3/8" stainless line that I installed for my prop governor and it worked fine. Use lot's of oil and don't do it too often.

Phil
 
with a fuel injected system

I see that those folks who have posted here seem to be using carbs and gascolators which is the setup that William is using. Does anyone have input as to the installation method and location of the fuel transducer in a fuel injected application?

My understanding is that the generally accepted best practice is to put the transducer beetween the injector servo and the fuel divider. Pics would be appreciated.
 
Beetween eng fuelpump and FI.

Hi.

I've put it beetween the engine driven fuelpump and the FI. That was the only place I could find which had 5 inches of straight line on each side of the FF sensor.

Since it's not supposed to be bolted directly to the engine, mine is "hanging" on the fuelline, thus having some flexibility.
I've installed an Adel clamp on the fuelline where the fuel line passing the induction tube from the forward left cyl.

I've also installed several heatshields.

I've installed firesleeve, covering the whole FF-sensor.
The location is slightly forward of where you can see the white label is sticking out from the firesleeve.

I'm alittle concerned about what the sharp corners of the FF-sensor will do to the firesleeve over time, but I guess only time will tell... and that's why we've Phase 1, right? :)

I'm also alittle concerned about what the added weight (ff-sensor and firesleeve) will do to the the 90* bend. (the bend where the fuel line exits the fuel pump.)
Maybe that metalbend can break over time?
One sollution would be to replace the whole fuel line with a new fuel line which had straight fittings in each end.
Then the fuelpump end could be secured with an Adel clamp as well.

Comments appreciated folks!











 
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Your set up is almost identical to mine. Only difference is that I have a 7A and thus the engine mount supports are in a slightly different location. I was able to run the fuel line a little higher up.

I originally had the flow sensor mounted to the engine mount via some right angle aluminum and adel clamps. I was advised by a very knowledgeable builder that it was too secure. There wasn't enough flex in the fuel line between where it was attached to the engine and engine mount. Thus the sensor is only secured by the fuel line. The sensor is very light, so I'm not worried about it.

I similarly wrapped everything in fire sleeve and used heat shields on the exhaust. Looks like you've done the right thing so far.

I've had no troubles in nearly 100 hours.

I can't tell if that is lacing or tie wraps on the engine mount tube. Tie wraps I've heard can eventually eat through the powder coating.

Also, I used some thinned out RTV (I even found red) on the edges of the fire sleeve to keep that white material from soaking up oil.

Dave
 
Plenty of room here....

my.php
Reads accuratley to the 1/10th of a gallon, or more than I can measure. 85 hours no issues. Keeps nice and cool in the plenum.
 
Sparks & Gas?

I'm concerned with the proximity of your solenoids and battery to the fuel. Call me chicken:mad:
 
I posted this before and still maintain that it really worked slick. I put the flowscan between the elec. fuel pump and the gascolator on the inside. Some were concerned about filtering, but I neglected to say that I used an Earl's 1" fuel filter before the fuel selector valve from each tank. Didn't want to take any chance on getting something stuck in the small orifice. The filters mount parallell right in front of the spar. The flowscan has the straights it requires and then goes through the firewall right into the gascolator right where Van's show it on the 7. Putting it outside is just too close to the sparks for me.
 
Fuel Flow Sensor - Where to place

First of all, thanks to everyone. This site has save me hours of trouble because others have made the boo boos. This is my first response

Research of where to put the sensor, it appears to have many opinions.
From my research, it appears that the only thing I can determine is the sensor must be level and have the wires coming out the top. I contacted the company and was told it was because of the vent. OK....I can accept that. Secondly, avoid angles coming into the sensor because turbulent flow can give you a poor reading.....I can accept that. Some suggest it should be after the mechanical fuel pump. Tough to do with the hoses Vans supplied and I'm not sure that I want to go there. Because it is a mechanical device and measures flow of fuel, somewhere in line that is stable and will give me an estimate of flow is acceptable. I sure don't want to have a vapor lock......Does it really matter where the darn thing goes?

Frankly, I don't care WHAT the meter shows most of the time. I do care what it shows when I'm traveling in straight and level flight as an estimate to what I might be using. Call me old school but I file an instrument plan for my long trips and plan by hours in the air. As we all get older, my bladder usually determines how long I go before refueling. Can't say I don't enjoy the $100 hamburger on the way. And I can promise you that I would not depend on a fuel flow sensor over a Timex.

I'm working like a demon to finish my RV7A and starting to tire of building. Fortunately, it is nearing the end. This one little detail has come back to me that we get hung up in the details and it really doesn't matter whether we burned 23 or 24 gallons. Only that we still had an hour left in the tanks.

As they say, I love you guys. You've been an inspiration to me to keep going and get it flying.

BTW - planning to put near the boost pump to keep the runs as short as possible FWF. If it doesn't read well on the Dynon, will reconsider location. Gotta do it somehow and it's the best I can tell right now for me. I can't see why it would make a hill of beans difference FWF when it still is before the mechanical fuel pump. Also hides very neatly.....
 
well here is what i call the finished product less fire sleeve. i used the parker rolo tool. it wont take an awful lot of stainless flairing but looks totally unaffected after flairing 8 flares. i deburred the tube well to prevent a cutting edge and used ample lube (bolube). the bender however shows no signs of wear but i think if i bent a couple of more pieces will probally break at some point. warmed to about 180 degrees f then bent it..now i know 180 isnt much but it would not bend a 45 degrees f. with my short bender. also nothing wrong with being chicken..;) but whats the difference? the vapors are whats gonna ignite and i cant get them that far apart.:confused:
this area would only leak fuel during boost pump operation not in cruise....it would then suck air. which would lead to fuel starvation...which would lead to me turning on the boost pump but not actuating solenoids. but then i may turn off the master for my soon to be ditching and that could lead to the collapsing field of the solenoid causing a spark if i left my diodes off and ...there are toooo many possibilities. built light, right, and tight.:D





firewall doubler, the bolt nut in upper left corner ties it to the battery box.


ya'll have a great weekend. i got building to do.
 
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Thanks

Hi.

Thanks for the feedback about my setup and for the tip about putting high temp sealer on the white edges of the firesleeve!

It's lacing cord on the engine mount. We're trying to avoid using nylon wraps if at all possible since I've read so much about it here.

PS: check out my home made extension to the mix bracket in the bottom pic. It seems to work fine so far...
 
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Cytoxin, if you use all-metal locknuts to hold down the Fuel-Flo sensor, you can adhere to the principle of no-Nylocks FWF.
Leland
 
:confused: they are all metal lock nuts, unless you are talking about the ones on the inside of the firewall.....
 
Webb said:
And I can promise you that I would not depend on a fuel flow sensor over a Timex.
Click to expand...

IMHO, the only reason to put in a Floscan is that it should be more accurate than a "Timex". After you get the unit calibrated, it is significantly more accurate than a watch, which is born out in my experience. I mounted it just above the gascolator as shown by others in this thread on my -7A.

You'll really appreciate the Floscan when you've encountered headwinds stronger than forecast. Inflight, you'll know your fuel condition very accurately and can plan accordingly. No more thinking and hoping you'll have enough fuel when you don't.

Mike
 
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