Gascolator and filter

[Dravenelle]

Hi

I need info with this...

I have a gascoltator on my plane..and do you use a filter if you have a gascolator ?

Dave

[rogerh12]

I myself have several fuel filters in my system, one of which is just before the carb in case something gets past the gassolator screen.
Roger

[jtpitkin06]

Dave,

Just a personal quirk... but when I have a question about how to put together an aircraft system I look to the certified aircraft manufacturers and how they have done it. I don't try to reinvent the Wright Flyer.

My fuel system has but a single filter. The gascolator. That's how they do it in most certified aircraft so it's good for me. The gascolator internal screen traps the junk and every time you pull the drain release on pre-flight it flushes the filter screen. Gascolators work and they have sufficient surface area on the internal screen to prevent fuel starvation if you get a tiny bit of dirt. You would have to encounter serious fuel contamination before one of these will get clogged.

It's my personal opinion that the small automotive inline filters have no place on an aircraft. I've had them stop the fuel flow on my cars, trucks, lawn mower, tractors, golf cart and a Miller Bobcat welder/generator. With that kind of tack record there's no way I'll put one on an airplane.

I think a good design is one with a low sump tank to trap any sediment. The Kitfox has just such a tank with the header mounted behind the seat. The quick drain valve on the bottom of the header is at the low part of the system to check for debris. The fuel to the engine comes from a slightly higher pick up point to prevent contaminates from going to the engine.

Gascolators are certainly more expensive than the cheap automotive inline filters, however, that's one area I will not try to save money.

One other thing about installation. Pace your gascolator where it is a bit higher than the bottom of the firewall. Use the type with a pull handle and a tube extension on the drain. Do not install any quick drain valve or fuel component protruding lower than the airframe. In the event of a forced landing in rough terrain the gear is likely to shear off and so will any exposed fuel drains. There's no sense in adding gasoline to the wreck site.

Hope this gives you some food for thought.

John Pitkin
Greenville, Texas

[kitfox2009]

Hi Dave
I have no filters in my system. Only the fine screen in the gascolator. In 200 hours I have had no issues. Actually, the inspector would not approve an "in line" filter anywhere in the system. Apparently problems have occurred with moisture swelling the membranes and restricting flow. I buy my fuel at a bulk dealer and store in a 45 gallon drum. I have a very fine filter cartridge and water separator on my hand pump. I also hanger the a/c.
Cheers
Don Model 5 Vixen 912UL.

[rogerh12]

FYI: If you have one of the Ellison Throttle Body Injector carbs, they have super small holes for the fuel (in order to atomize the fuel) and require a fuel filter with 70 micron or finer filtration (I use a large paper auto filter myself, if it expands, it still has good fuel flow in my experience.).
Hope this helps
Roger

[rogerh12]

I noticed Aeromotive makes a sweet replaceable FABRIC element fuel filter, with 10 microns of filtraton, but it's not cheap:

http://paceperformance.com/i-6486174-aei12301-10-micron-orb-10-red-fuel-filter.html

[kitfox2009]

I also notice it states not for use with E85 or alcohol.

Cheers
Don

[t j]

Hi

I need info with this...

I have a gascoltator on my plane..and do you use a filter if you have a gascolator ?

Dave

Dave, make sure the screen in your gascolator meets the specifications needed for your engine and carb.

My two stroke Rotax installation manual says a 0.15 mm (150 microns) fuel filter is needed. I used the aircraft spruce gascolator with the 120 micron screen and no other filters in the fuel system. http://www.aircraftspruce.com/catalog/appages/acsgascolator.php

[HighWing]

Wow, John, I don't know where you buy or store your gas, but none of these have ever happened to me and I am as old as dirt. I would be willing to wager that 80 to 90 :mad:percent of flying Kitfoxes have inline filters. Then keep in mind that the certified aircraft you refer to have either aluminum tanks or rubber bladders. I know of at least one reported instance when glass fibers from the wing tanks clogged a gascollator screen. And it was a s tricky diagnosis as, as you suggest, the fibers dropped from the screen, but were too long to exit the quick drain and were invisible on the bottom of the bowl. Then reassemble and over and over again.
For the sake of argument, I put 900 you're on a Model IV with the purelator glass filters and have them on my current project. Good thing they call these puppies experimental, I guess.

[szicree]

I know of at least one reported instance when glass fibers from the wing tanks clogged a gascollator screen. And it was a s tricky diagnosis as, as you suggest, the fibers dropped from the screen, but were too long to exit the quick drain and were invisible on the bottom of the bowl. Then reassemble and over and over again.

With no gascolator and just small inline filters wouldn't this have stopped things up just as well?

[Slyfox]

OH man. Throw that gascalator as far as you can. PUt an automotive inline plastic filter, 1/4 inch ends just after the on/off valve. replace the filter once a year at your anual and forget it. I don't have one of those things on my rv either. I've read more problems with leaks and such with a gascalator that I will not use em. Going flyin', yup with an auto filter.

[Dave Holl]

Hi
I would not touch a small inline automotive filter, buy a good quality gasolator such as the andair ones expensive but good quality and large filter area.my certified a/c has course finger strainers in the tanks, a large gasolator and a filter in the mech pump(0-200) and in 30 years of flying I have not had any fuel problems and this will be the system I am fitting in my mk7!!!

[rogerh12]

Thought I would just scare you all a bit: During annual inspection, the drain stem on my gasolator was found to be loose !!!! If that fell out in flight, there goes all my fuel !!!! Another guy (not me this time) that my A&P annual’ed was complaining because he only put 5 hours on the plane that year and didn’t need an annual. Turns out, his battery had leaked and dripped on his elevator control cable!!!. Only 3 strands were left !!!!!
Don't every let them tell you that you don't really NEED an annual inspection. It’s hard to beat a second set of experienced eyes…..
Roger

[Dravenelle]

Great

I have a gascolator in my plane .....go with him.

David

[Dave F]

OH man. Throw that gascalator as far as you can. PUt an automotive inline plastic filter, 1/4 inch ends just after the on/off valve. replace the filter once a year at your anual and forget it. I don't have one of those things on my rv either. I've read more problems with leaks and such with a gascalator that I will not use em. Going flyin', yup with an auto filter.


Total Mis-information
use a gascolator. >> period. <<

Dave

[Grady]

I have a gascolator in my plane and like it very will, but check it and carbs often.

Kitfox 4 rotax 582
Grady

[HighWing]

With no gascolator and just small inline filters wouldn't this have stopped things up just as well?

OK. If your gascolator clogs you are going down, period! I had a gascolator on my first Kitfox, ca 1998. Then the talk in the Fox community was that because the low point in the system for water accumulation was the header tank, why the duplication? Then came the header tank low fuel warning systems. For me, the way it was and the way it will be (minus the gascolator this time) - Wing tank, online filter - glass Purelator (in pilot view) low fuel indicator, header tank, electric fuel pump, fuel valve, engine driven fuel pump. Clogged filter, I will have 30 minutes fuel in the header tank to find he best place to put it down.
Lowell

[rogerh12]

Hey HighWing - You forgot the secondary fuel bypass line, with hand squeeze bulb, just in case your loose both fuel pumps and clog all the filters at the same time !!!!!!
Roger

[DesertFox4]

Could it be we found another subject as controversial as engine choice or nose gear vs tail wheel?;)

[Av8r3400]

Could it be we found another subject as controversial as engine choice or nose gear vs tail wheel?;)

Maybe if we try real hard... :D

[jtpitkin06]

[long posting]
Ladies and Gentlemen,

We have a lot of first time builders and prospective buyers that lurk on this forum looking for guidance.

I would hope this forum can be a place to exchange ideas and opinions. Instead of saying builders should throw one component or another into the weeds, why not list what you think are the advantages of your system of choice? Conversely, you might relate experiences that would steer you away from a particular component or system. I see little value in suggesting a builder should only take to the air in swathed in bubble wrap and wearing a gas mask if they don’t build it just like yours.

Alternate sources and solutions is what experimental aviation is about. We experiment, we learn, and hopefully we share. Some things work… some don’t. I will not fault anyone for trying something different.

As I see it, there are many different ways to plumb the fuel system; as well as where and what type of filter to install.

Here’s my take on two components.

First the gascolator

My publicly stated choice is the gascolator mounted forward of the firewall. I admit, it is a rather traditional choice having been used in aircraft for more than fifty years. A gascolator effectively filters out debris and small amounts of water. The filters screens are available from 10 microns to 140 microns.

The firewall location is not the lowest point in the Kitfox fuel system when the tail dragger sits on the ground, but there is a header tank behind the seat with a quick drain to purge any water during preflight that has settled in the header. In flight, the firewall gascolator is at, or near, the lowest point in the system.

Are gascolators failure proof? No. But the track record is pretty good at preventing more engine failures than causing them. I like them because of the ease of inspection. You can open them to clean the screen, look at any debris to track the source, and they have a large internal area that is unlikely to clog under normal conditions. Water passing though does not cause the screen to swell or create a blockage.

I like the advantage of being able to take a sample of the fuel during preflight for visual inspection. The sampling also flushes the screen a small amount so that a trend of contamination may be noted.

My gascolator uses AN fittings. I have aluminum fuel line from the header to the engine.

Does the gascolator have any disadvantages? Possibly.

During flight I cannot look at the gascolator and tell if there is any impending blockage. The cost at USD $70 is more than an auto filter, but the screens can be cleaned and reused many times. A new screen costs about USD $3.

Next: Automotive inline filters

The big plusses I see of automotive filters are cost and availability. The low cost allows a builder to install multiple units and change them frequently.

The auto filters come in many configurations lending them to ease of installation.
They can be installed with hoses or hard line. Normally a hose and a clamp is all that is needed. With proper maintenance the installation is perfectly adequate.

Many auto filters are transparent, allowing the user to visually inspect the filter.

The internal element is usually a paper or fiber type with very good fuel filtering capability.

The disadvantages for me are:

The paper element can swell when saturated with water, causing the filter to block fuel flow. For automotive applications that is a good thing as it will stop the engine before water can get to the carburetor or injectors. I would rather an aircraft engine continue to run, even if poorly, than quit.

I find looking through the plastic to inspect for debris is less than accurate. A plastic filter can look new and be completely blocked.

Automotive inline filters are typically plastic bodied with hose barb ends. I prefer the metal body of the gascolator with AN fittings.

There is no quick way to sample fuel from an automotive filter during preflight. Installing one low in the system is pointless as there is no way to flush it to drain any water.

Personal Experience

I’m sure different builders have reports of failures from either system. If enough debris or water gets into the fuel system, either an automotive filter or a gascolator will clog and the engine will quit.

I live in an area with high humidity and water in fuel systems is common. I drain lots of water from airplane tanks and sumps in the summer. We can get 90 degrees and 90 percent humidity here in East Texas.

I’ve had too many of my farm vehicles quit when a filter swelled with water. Because of the experience with the farm equipment, I wouldn’t install one in an aircraft. It’s just a chance I don’t want to take and flying with one is outside my comfort zone. Your experience may be just fine in the arid zones of Central California or Arizona.

This posting is merely my personal opinion and a chance to share my thought process as to why I choose the gascolator over automotive inline filters. It is not gospel and I won’t flame anyone for doing it differently. I welcome your experiences.

John Pitkin
Greenville, TX

[szicree]

My gascolator uses AN fittings. I have aluminum fuel line from the header to the engine.

I'm sure you mean to the firewall and not all the way to the engine, right?

[HighWing]

I agree with John for the most part. What troubles me a little bit is the wealth of information over more than 15 years of Kitfox discussion group input that apparently begs to be ignored. Just for fun, I checked the archives of another board and got 400 hits on gascolator. Many of my posts reflect the wisdom of brighter minds than mine. If some of you want to poke fun while reinventing the wheel, no problem here as long as the genuinely curious mind gets the full spectrum of ideas.
Lowell

[Dorsal]

I simply followed the engine install instructions, headertank for sump, in-line for the filter. I replace the filter every 100 hrs (done so once, about to again) and inspect it. Seems to me there is enough track record to suggest multiple acceptable approaches.

[rogerh12]

John;

Ok, seriously now; you point out an interesting thing about using inline automobile fuel filters. Even though the paper element can swell when saturated with water, causing the filter to block fuel flow, we CAN use them safely if they are only located just before the fuel enters the carburetor and as long as a gassolator is the at a lower point in the fuel system so as to remove any water BEFORE it gets to our cheap but effective auto fuel filters.

You agree?

Roger

[Dave F]

Great response.
Very factual --


YEs paper ones are not the best choice. I too have seen them swell up.

What has Denney, Kitfox and now Mc Bean put in builders manual ?

Dave





[long posting]


I’ve had too many of my farm vehicles quit when a filter swelled with water. Because of the experience with the farm equipment, I wouldn’t install one in an aircraft. It’s just a chance I don’t want to take and flying with one is outside my comfort zone. Your experience may be just fine in the arid zones of Central California or Arizona.

This posting is merely my personal opinion and a chance to share my thought process as to why I choose the gascolator over automotive inline filters. It is not gospel and I won’t flame anyone for doing it differently. I welcome your experiences.

John Pitkin
Greenville, TX

[MotReklaw]

"Great response.
Very factual --


YEs paper ones are not the best choice. I too have seen them swell up.

What has Denney, Kitfox and now Mc Bean put in builders manual ?

Dave"

My KF SS manual for the Continental O200 calls for a gascolator.
Thanks

[wheelerg]

As i am a new member and new to the Kitfox, i must say i really enjoy reading the different view points put forward by members.....its a learning experience for me . thanks and keep the info coming, cheers

[Dorsal]

My s7 fwf kit called for and included an in-line filter to be placed just before the fuel pump. Not sure how water is going to get to it if you sump the header. I am also a bit surprised by the passion for the topic give there must be thousands of planes in either configuration. I certainly don't have any strong opinions on this just did what the good book told me.

[Geowitz]

Anyone have any thoughts on this?...

I've got a little different situation. I have an HKS 700T. Still working through the install, but the manual calls for a pre filter somewhere in the system before the fuel pump. Gascolator may be nice for this and would allow for sump inspections, but not really neccessary in my opinion as any water that may collect is forced through or totally mixed in the return line from the fuel pressure regulator. A little water injection during warm up won't hurt anything anyways. Also, my header tank is the low point with a sump for the majority of water in the system. Basically my concern is more about debris. My thoughts are to put a see through(NON paper) filter between each tank and the header and then after the pump there is a finer filter that is supplied with the engine.


Lowell - Had a specific question for you... In a previous post you mentioned you have had good results with the glass purolator filter. Seems to be some chatter online about ethanol camptability and what size mesh they are. Do you have any idea what the specs are for it? Can't seem to find them.

[HighWing]

Not much info on the purelator type inline filters. I do have a replacement element but there was no info on the packaging. I did look at it with 14X magnification. It looks very much like nylon mesh fabric as the filtering medium. A rough estimate - the pore size is pretty close to a couple of strands of hair width. I used my wife's hair as I couldn't find any of my own I could spare. Then I thought of something else. I scanned the filter at 1000 dpi and it looks like the pore size is something like .003 inches based on three pixels per. For my airplane, I don't worry about ethanol and the filter element or water, for that matter.
Lowell

[Geowitz]

You mean you don't use auto fuel with ethanol in the first place or that it hasn't been a problem?

[HighWing]

Sorry about the confusion. I had no issues with ethanol while I was flying my first airplane. It had the purelator filters for the entire 900 hours, with ethanol for the last three hundred or so. My concern now is with the new ca. 1992 kreemed tanks I now have on my new project. I think I will use avgas until I start flying as I don't want the ethanol laced fuel just sitting there while I get the last few things tied up. I plan on an engine start in the next week or so, but probably won't fly until late April or early May. The plan then is to use auto gas as it will be topped up regularly and be kept fresh.
Lowell