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AVGAS used Ian.

Plane has sat for a day or two now, checked it today, filter still above half full.

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it's just magic and money and away you go. Nev

After reading all the fear here I don’t think I’ll ever fly again, just too risky😂😂

A barbed comment.

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Hi Skip,

We weren't talking about sales were were talking about design.

You were of the opinion that paper filters were no good and ventured the opinion that mesh filters were the "aviation grade" ones which could be seen as a sales gimic.

Nev mentioned that he wouldn't use a filter without barbs as the filter you displayed didn't have barbs.

You then stated that barbs were just for a warm fuzzy feeling.

Thruster88 showed a hefty turbine with an paper filter

I stated that barbs and raised collar provided a mechanical advantage especially when used with a clamp.

 

The rest is just going around in circles.

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9 hours ago, Ian said:

Hi Skip,

We weren't talking about sales were were talking about design. You sited Kitplanes - a promotional publication closely allied to sales as is journalistic commentary on most products.

You were of the opinion that paper filters were no good  - My comments centered on what I see as garden engine fuel filtration product's (the small el cheapo paper types ). Never said they are no good, strongly suggested they are not appropriate for aviation use. and ventured the opinion that mesh filters were the "aviation grade" ones which could be seen as a sales gimic. - Who said anything about aviation grade? True I see a fine mech filter, encased in a light weight, transparent, almost indestructible casing, pretty much guaranteed not to leak,  as a preferable product to the aforementioned garden variety

Nev mentioned that he wouldn't use a filter without barbs as the filter you displayed didn't have barbs. So?

You then stated that barbs were just for a warm fuzzy feeling. Yep! The good old barb, very much superseded by the better designs I  (& you) referred to.

Thruster88 showed a hefty turbine with an paper filter I acknowledged the Aviation Certified pleated "paper" media filter, fully tested, quality controlled throughout manufacture and suggested it bore little resemblance to the garden variety that this post centered on - your point?

I stated that barbs and raised collar provided a mechanical advantage especially when used with a clamp. I have always supported the raised collar/single smooth barb design of fitting (along with the plain pipe/tube) and the use of appropriate clamping system. I am implacably apposed to the old style multi barb (beloved by so many) but agreed it gives a "mechanical" security , completely negated by its poor sealing performance and potential to damage the inner lining of the hose - what is your point?

 

The rest is just going around in circles. Like so many oft repeated  discussions on this Forum - still little gems arise from time to time to keep one interested

 

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I use the Cooper type coated paper filters and change them every 50 hours. I always perform a fuel drain sample check before each days flight and after refuelling and always use my Mr Funnel except when at a bowser. Coated paper filters are used extensively in the automotive and aviation industries and how often do you hear of a problem? 

 

I use Mogas 98 almost exclusively except when all I can get is Avgas. I once found a small amount of water in the sample after not using the aircraft for a few weeks with only about 1/4 full tank in humid summer conditions. If you are getting water in your fuel regularly and have your aircraft stored outside you need to seriously look at the effective sealing of the fuel cap and access via the breather.

 

When I replace the filter, the air inside it has to be replaced by fuel so the only place for it to go is through to the carburettor. I charge the carburettor normally by running the electric fuel pump for 10 seconds before starting the engine. After running for a few minutes I shut down and check for leaks ( also have done an oil change & other maintenance) & the fuel filter usually has fuel in the bottom 1/4. It slowly fills up over several hours running but never gets completely full. The fitted filter slopes down towards the exit at around 20 degrees.

 

 

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You do a good job all round from your comments JG. .IMHO

     The only way to remove bubbles is by high(er) velocity flow. It won't hurt the Carburetter which is vented. With fuel injection it's not so easy and can render a pump ineffective by cavitation. IF that is VAPOUR it will respond to cooling. I would suggest it's mostly AIR.  Peeling off via a small bleed from a high point will eliminate it as is often done in liquid cooling systems where air may cause hot spotting in the engine.  Whether this is necessary or not is a good question. .Nev

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AVGAS used Ian.

Plane has sat for a day or two now, checked it today, filter still above half full.

I was hoping that you were using mogas and was going to get you to try avgas and see if the issues went away. :-(

The volatile components of mogas vary somewhat and are higher than avgas.  Also winter blends may contain higher proportion of volatile components compared to summer blends.

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Hi Skip,

The thread became confused because Nev stated that he would prefer a barbed fitting to the barbless one you were recommending.

Images were shown of your recommended fitting and a fitting showing a single barbed or collered fitting.

Comparing the images you showed a straight fitting and the comparision object was a single barbed.

You responded effective stating that barbed connectors were marketing drivel. Right after the image of the single barbed connectors (I think that this led to the confusion as you've indicated you really dislike the multibarb type and felt the urge to make this point, we get this now 😉

 

Of the pictured images are you happy with the claim that the coopers filter with the barbed neck provides a better mechanical fit and greater pull off resistance than a straight connector or the type that you displayed?

So in an ideal world your ideal filter would be a mesh filter with a single raised barb or collar  (Given all other things are equal)

 

The reason that I cited the Kitplanes article was simply because it was relevant to the discussion at hand and I thought that it was a reasonably balanced approach, yes there were some mentions of some brands however he also provided some good advice about making and connecting hoses. We're big kids and know that if the article mentions ponies we may choose to not buy a pony.

For example it did make me think about areas where marking fittings might make sense.

 

image.png.1b49679f9a91559a21e08e545a16e890.png

 

I was taking to someone the other day who said that on a flight after some off site maintenance they noticed that their foot was really cold and realised that fuel was coming in through a vent. It was a fuel line issue which was created while doing the other work.

 

 

image.png

Edited by Ian
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Ian, I think Skippy made the point he detests (sharp-edged) barbed fittings because of the potential for hose damage via movement to the hose where its in contact with the sharp edge of the barb.

That is where the Hengst filter is Skippys preferred choice, because the Hengst filter doesn't use a sharp barb, it uses a smooth spigot. But the best solution to prevent hose slippage, is the rounded bulge in the spigot.

 

Edited by onetrack
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Mogas is based on the aromatic compounds of petroleum whereas Avgas is based on paraffin (the flammable component of candle wax) & requires the poison TEL (tetraethyl lead) to achieve its 100 RON value. High RON Mogas has a number of aromatic additives including toluene, benzene & xylene and does not require TEL to achieve its 98 RON value. The aromatics are lighter and evaporate off first. They can't evaporate off if contained within a sealed fuel system or container so they won't evaporate in the fuel filter as its volume is tiny.

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Whatever the %'s the fuel system must be right as there's no repairs in the air. I also like to PROVE a tank over  a place where a landing is possible if it's a homebuilt and not familiar to me and I'm switching tanks.. . Back up with electric pumps  for T/O and landing. Best to have more than one tank with KNOWN fuel above minimum for safe go around.

 Remember Mogas is not a guaranteed product to the purchaser. It can be contaminated at any point deliberately or by accident. Drums are probably better from a bulk distributor. A sealed Drum of avgas has a release note.. Fuel test for water? Use paste if possible where the plane has sat for a while, especially.  Nev

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I've never seen a good hose internally damaged by a barbed ring. You usually have to put a longitudinal cut in an age hardened hose to get it OFF., Nev

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6 hours ago, onetrack said:

Ian, I think Skippy made the point he detests (sharp-edged) barbed fittings because of the potential for hose damage via movement to the hose where its in contact with the sharp edge of the barb.

That is where the Hengst filter is Skippys preferred choice, because the Hengst filter doesn't use a sharp barb, it uses a smooth spigot. But the best solution to prevent hose slippage, is the rounded bulge in the spigot.

 

Thanks Onetrack: in addition to your correct observations'

 

I feel that old style  multi barbed (still available & many fitted) do not seal as well as the smooth pipe with collar or even just plain pipe (spigot).

 

It also seems to me that people who use the multi barb, tend towards an over reliance on the hose clamp for making a seal - to achieve this, they use what I would consider, to be excessive tightening of the clamp (often still not completely successful).

 

I also tried to make the point that hose ID must be a close match to fitting OD for a successful long term seal. Using the clamp as a hose "reducer" is, at best a short term solution and at worst a failure just waiting to happen.

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did we ever get an answer about why there was no fuel in the original filter...???

 

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9 hours ago, robinsm said:

did we ever get an answer about why there was no fuel in the original filter...???

 

Pretty much - fuel vapour occupying the space.

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I've suggested it's air  and it can be tested by say putting an ice pack around it and see what happens.  That will decide the matter. Nev

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30 minutes ago, facthunter said:

I've suggested it's air  and it can be tested by say putting an ice pack around it and see what happens.  That will decide the matter. Nev

Nev; In my experience, transparent filters fitted to ground based engines, is that it is common for a nice clean filter to only have a small amount of liquid fuel showing at any time.

Over time, the filter may progressively become "blocked" and the level of liquid fuel rise accordingly.

 

So my low tech interpretation/speculation is;

The fuel enters the larger volume of the filter canister and much of it vaporises (clear) leaving a small liquid pool, with a vapour layer above (not air). I assume that the out going pipe is filled (mostly) with liquid fuel.

As the filter becomes less permeable, the effect of a change in volume is diminished and so the visible liquid level rises.

 

This effect is most marked in gravity fed filters fitted/lying in the horizontal plain but can also be seen in those fitted vertically. Filters subject to vacuum (pump) seem to be less prone probably because of the more positive/aggressive fuel flow.

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I reckon it is mostly air with some fuel vapour present. If the filter is mounted horizontally the pump (electric or mechanical) will suck air through till there is enough fuel in the filter to exit the filter. The air pocket will slowly shrink as oxygen & probably nitrogen slowly become absorbed into the liquid. If the filter is mounted vertically it is likely to have a much larger air volume as fuel enters falls to the bottom by gravity and exits via pump suction. The air volume will remain fairly constant as it will always be at the top of the filter but the filter will slowly get more fuel volume as the gasses become absorbed.

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3 hours ago, kgwilson said:

I reckon it is mostly air with some fuel vapour present. If the filter is mounted horizontally the pump (electric or mechanical) will suck air through till there is enough fuel in the filter to exit the filter. The air pocket will slowly shrink as oxygen & probably nitrogen slowly become absorbed into the liquid. If the filter is mounted vertically it is likely to have a much larger air volume as fuel enters falls to the bottom by gravity and exits via pump suction. The air volume will remain fairly constant as it will always be at the top of the filter but the filter will slowly get more fuel volume as the gasses become absorbed.

So, in a vertically mounted cylindrical filter, with central in/out fittings , how do you explain an visibly clear area, above the liquid ?

 

Logic would suggest, that either the air/gas migrate back up the inlet pipe (if so oriented) OR if the other way around the pump/engine would remove the air/gas, until exhausted, leaving just liquid fuel in the filter - this is not what happens..

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In my example, the filter is slightly inclined upwards towards the OUT end, which leads to the engine driven pump, and from there to the carb. The routing (not the angle) is as per Jabiru instructions of the day. 500+ hours and 16 years operation like this. So in the filter, tank side is fuel, engine side is air. Have tried a few things to purge the air but nope. I am glad that I do have the clear filter so that I can see what is going on and see if ever anything accumulates in there, dirt, muck, debris, a possum, etc. never had anything in the filter.

I'm convinced that my occasional fluffy idle started when I changed filter brand. My records show it to be true. True as in, that's when it all began, almost right after, but I've only just realised.

I'll need to fly some more before declaring "case closed"

Or I might go back to the original spec RYCO Z14 fuel filter, but alas, they are made who knows where overseas now too. RYCO overseeing quality control these days? Who knows.

RYCO ceased the remaining half of their filter manufacturing in Melbourne in Feb 2005. Since then, everything is sourced overseas.

 

 

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