Fuel Filtration

[skippydiesel]

My new aircraft is fitted with an ACS Gascolator 10584 - I am trying to work out what size (filtration) the screen is.

 

Could be 120 Micron OR  70 Micron (the later being the preferred). Any suggestions as to how to find out?

 

Strangely the ACS 10584 does not appear on the Nett, just the 10580 (which looks identical)- I assume my gascolator has either been superseded or I have the numbers wrong - what think you?

[onetrack]

Skippy, it appears the ACS 10584 (indicated in photos as 10584HP) has been replaced by ACS 10585HP. Google picks up an image of 10584HP on Aircraft Spruce in an image search - but when I click on the image, the page that appears is the one below - showing 10585HP in the vertical view, and 10584HP in the horizontal view. The standard mesh screen is quoted as 120 micron.

 

https://www.aircraftspruce.com/catalog/appages/gascolators1.php

[Blueadventures]

33 minutes ago, skippydiesel said:

My new aircraft is fitted with an ACS Gascolator 10584 - I am trying to work out what size (filtration) the screen is.

 

Could be 120 Micron OR  70 Micron (the later being the preferred). Any suggestions as to how to find out?

 

Strangely the ACS 10584 does not appear on the Nett, just the 10580 (which looks identical)- I assume my gascolator has either been superseded or I have the numbers wrong - what think you?

I'd email the company ACS with an image of the item and ask them.  Never know it could be a Chinese knock off and they got the part number wrong; stranger thinks happen these days. 

[skippydiesel]

Thanks guys - ACS have advised that the part number I am using is just for the top (cap) of the gascolator and that the whole thing is a 10580. The HP is for high pressure - definitely not mine

 

Two filter screens available  - the standard 120 micron and a finer 70 micron.

 

I think the only way to be sure that I have the 70 micron will be to purchase a new one.

[Thruster88]

It is a good looking filter in terms of easy servicing and security. 

 

One slight down side to the finer mesh, 70 microns, is increased chance of blockage. Gunk smaller than 120 micron, 0.12mm, would surely pass through the carburetor without causing a jet blockage?

Edited October 8, 2022 by Thruster88

[skippydiesel]

2 hours ago, Thruster88 said:

It is a good looking filter in terms of easy servicing and security. 

 

One slight down side to the finer mesh, 70 microns, is increased chance of blockage. Gunk smaller than 120 micron, 0.12mm, would surely pass through the carburetor without causing a jet blockage?

I plan to have a 150 micron "rock collector"  inline before the Gascolator.  This should remove most, if not all or the larger bits before the fuel enters the gascolator/70micron.

 

I will also carry a spare rock collector.

 

At this stage the rock collector could be a Hengst H 102 WK, a Baldwin BF 17850 or a Baldwin BF 7863.

 

I already have the Hengst  H 102 WK & Baldwin BF7863.  

 

The Baldwin filters are 150 micron. Waiting on Hengst to tell me what their filter is. 

 

Both Baldwin filters have a larger capacity & filter area than the Hengst.

 

I have used the Hengst filters for about 11 years - found them to be excellent. Previously I had a Hengst on each tank (x2) + one on separate boost pump fuel supply).

 

New aircraft , 3 tanks,  only has a single filter - the gascolator -  located after the boost pump & before the mechanical (Rotax).  I am not happy with this arrangement and will , at some time in the near future, introduce a filter for each tank

Edited October 8, 2022 by skippydiesel

[Thruster88]

All aircraft fuel tanks should have a finger filter to prevent the outlet becoming blocked by a "gumnut"

 

Having coarse filters before a fine, 70 micron, filter will do nothing to reduce the risk of the fine filter blocking in the very rare event the tank becomes contaminated by fine gunk. The ACS filter does not have a huge surface area with that single flat disc strainer, however it will capture all those course items and keep them in the bottom of the gascolator for your viewing pleasure, unless one of those course items causes the drain to not shut off and you suffer fuel exhaustion due to lost fuel. (Thinking about the recent jabiru in the top end).

Edited October 8, 2022 by Thruster88

[facthunter]

You should always check your fuel drain has sealed by twisting it a little as you remove the drain tube. It's only held closed by a spring in most arrangements.  Flying safe is about checking things that matter. Nev

[skippydiesel]

15 hours ago, Thruster88 said:

 

Having coarse filters before a fine, 70 micron, filter will do nothing to reduce the risk of the fine filter blocking ...................................

I don't understand your logic here Thruster.

 

Progressive fuel filtration (course to fine)  is a common strategy in very many ground based applications. The course pre filter (often referred to as the"rock" filter) removes larger fractions, preventing them from being caught by the finer second filter.

This goes some way to addressing concerns about a batch of contaminated fuel blocking the engines only fuel supply leading to engine failure. It would be a rare situation indeed where all/most of the contaminants would pass through the rock filter and block the fine.

The overall effect of progressive filters is that of increasing the total filtration area.

[Thruster88]

I am saying any coarse material that can pass through the in tank finger strainer will not block your fine filter in the gascolator because they will fall to the bottom of the gascolator.  

[Blueadventures]

27 minutes ago, skippydiesel said:

I don't understand your logic here Thruster.

 

Progressive fuel filtration (course to fine)  is a common strategy in very many ground based applications. The course pre filter (often referred to as the"rock" filter) removes larger fractions, preventing them from being caught by the finer second filter.

This goes some way to addressing concerns about a batch of contaminated fuel blocking the engines only fuel supply leading to engine failure. It would be a rare situation indeed where all/most of the contaminants would pass through the rock filter and block the fine.

The overall effect of progressive filters is that of increasing the total filtration area.

One point I agree with Thruster is that anything that passes through 70  microns will be digested by the Carby and not cause any jet etc blockages.  Its not like filtering potable water etc.

[Blueadventures]

4 minutes ago, Thruster88 said:

I am saying any coarse material that can pass through the in tank finger strainer will not block your fine filter in the gascolator because they will fall to the bottom of the gascolator.  

I'm a believer in gascolators and recommend them if not fitted to a home build.  Had one in the Skyfox CA22.

[skippydiesel]

2 hours ago, Blueadventures said:

One point I agree with Thruster is that anything that passes through 70  microns will be digested by the Carby and not cause any jet etc blockages.  Its not like filtering potable water etc.

I think we can all agree that sub 70 micron  contaminants are very unlikely to cause carburettor jet  blockage.  Do you think the same of  a  120 micron filter?

 

If you reread Thrusters statement he is talking about filter blockage  (not carburettor blockage).

 

Thrusters comment is valid -  a fine filter, will trap more contaminants, than a courser - that's why you design a system with in line progressive filtration.

Edited October 9, 2022 by skippydiesel

[Blueadventures]

7 minutes ago, skippydiesel said:

I think we can all agree that sub 70 micron  contaminants are very unlikely to cause carburettor jet  blockage.  Do you think the same of  a  120 micron filter?

 

If you reread Thrusters statement he is talking about filter blockage  (not carburettor blockage).

 

Thrusters comment is valid -  a fine filter, will trap more contaminants, than a courser - that's why you design a system with in line progressive filtration.

Exactly; filter blockage = reduced or nil fuel flow to engine via carbs.  Hence his recommended advice / comment and I agree with such.  Perhaps then 120 is overkill for a carby engine??

[skippydiesel]

2 hours ago, Blueadventures said:

I'm a believer in gascolators and recommend them if not fitted to a home build.  Had one in the Skyfox CA22.

 

They are okay. I would suggest they were developed long before the modern in line filter. I don't know that I would fit one to an aircraft that did not already have one - bit heavy, prone to leaking and have very small filter area, relative to the size of the unit  - I used Hengst filters on my last aircraft (as stated one filter per tank plus one filter before boost pump) - much lighter, cheaper and easier to service than a gascolator. As an added precaution all my fuel was filtered into the tanks. In 11 years & 900 hrs I rarely saw any sign of water and only the occasional speck of "dirt". I serviced/inspected the filters every 50 hrs & replaced at 100. Never had dirt/water in my float bowls.

[Blueadventures]

I took it that you were fitting the gascolator to your project.  As stated I would fit one.  Yes; Hengst are a good small size in line filter and have been used in Skyranger model for ages.  The added benefit of the gascolator is the water trap, its size (quantity of fuel) and does not collect any debris in my system as the primary in line filters do that job.  I use a mister funnel so never dirt in filters.  When is your project in the air; will be a fun time.

[skippydiesel]

1 hour ago, Blueadventures said:

I took it that you were fitting the gascolator to your project.  As stated I would fit one.  Yes; Hengst are a good small size in line filter and have been used in Skyranger model for ages.  The added benefit of the gascolator is the water trap, its size (quantity of fuel) and does not collect any debris in my system as the primary in line filters do that job.  I use a mister funnel so never dirt in filters.  When is your project in the air; will be a fun time.

Project (Sonex Legacy) came with a gascolator of unknown filter value (could be either 120 or 74 mu) so inclined to keep it.

At this stage planning on installing  Hengst , Baldwin or similar, as a pre (rock) filter.

Sonex has 3 metal tanks. So far have only used one during stationary ground run ups - bit surprised at the amount of debris that is still being caught by gascolator. Just a very very small amount ending up in float bowl.

Sonex would be undergoing taxi runs right now, if it wasn't for NSW being pretty much under water.

Next opportunity, to transport to The Oaks airfield, for final assembly about 2 weeks away (weather permitting)

[Blueadventures]

Good your getting the swarth and other contaminants out.  always some and sometimes plenty. Some poor after welding etc practise see heaps of crap in the tanks.  Enjoy the taxi and workups.

[skippydiesel]

On 09/10/2022 at 10:36 AM, Thruster88 said:

I am saying any coarse material that can pass through the in tank finger strainer will not block your fine filter in the gascolator because they will fall to the bottom of the gascolator.  

Who ever said/suggested I have "finger" filters in my tanks.

I may have but don't know.

I will try & contact the first builder who either built or had built the tanks.

[skippydiesel]

I did ask about your opinion of 120 mu versus 74 mu - anyone like to wax lyrical on this?

[skippydiesel]

From Randy R Allen, Baldwin Filters Technical Advisor; 

 

"Nylon mesh is generally 200 mesh, which is 75 micron.  If the filter uses wire mesh it is generally 100 mesh, which is 144 micron"

 

[skippydiesel]

Some more information;

 

Rotax have a specification for the 912 ULS fuel supply;

 

912 Instillation Manual Section 73-00-00, page 7

 

"In the feed line from tank to the fuel pumps an additional fine filter with mesh size 0.1 mm (70–100µ) has to be provided. The filter has to be accessible for service. A combination of filter/watertrap (gascolator) is recommended."

 

So I guess I can either put a finer filter (50 - 75 mu) down stream of the gascolator (120 mu) OR use a fine screen in the gascolator (74 mu) that may be assisted by a course screen  (150 mu) up steam of the gascolator.

 

Pros & Cons

 

First option; would save me a few dollars as I have the filters/screens.

Having a down stream finer filter is attractive to me, as it means the gascolator removes most of the gunk & any water leaving the finer filter to clean up to Rotax specifications.

Using a "plastic" filter in the engine compartment - not a great idea

 

Second option:

Additional cost & effort

Finding a way to retrofit a relatively course filter (150 mu) before the pumps would mean the gascolator finer screen (74mu) would be relived of some "work" & the system would comply with the general recommendation to filter fuel before pumps.

 

Your thought's??

[onetrack]

All fuel systems with a satisfactory level of performance have a "primary" (coarse) filter before the primary pump, and a "secondary" (fine filter) before the carburettor or injection pump.

The coarse filter is sized to permit the largest acceptable particles through the primary pump without causing damage or shortened life to the primary pump. That filtering medium is usually around 150-200 micron.

 

The secondary filter is sized to permit the largest acceptable particle that will go through the carburettor or injection pump without causing damage or blockage.

That filtering medium can be as high as 200 micron or as low as 10 micron, depending on the clearances in the carburettor jets or injection pump valve clearances.

 

The higher the fuel pressure delivery, the finer the clearances, therefore the finer the filtering requirement. A carburettor can cope with particles that will clear the jet orifices easily, so find out the orifice clearance dimensions and select the filter fineness accordingly.

 

Ensuring no rubbish or water ever enters the fuel tank is the most important part of fuelling. Filters are only for debris that enters accidentally. Remember that using rags around fuel fillers can produce fluff which can impede fuel flow, moisture gathers in tanks via condensation, and detritus in tanks is related to how careful the filling process is.

One has to remember that filters must still be able to provide adequate flow if or when they become partially plugged. The length of time between filter cleaning governs the level of plugging.

 

A 70 micron filter will filter out silt and portland cement particles. Whether you need such close filtering is dependent on how much by way of silt-size contaminants you expect to get from a fuel tank.

I'd say only tiny amounts if you're anal about refuelling cleanliness. A 120 micron filter is more than adequate for every carburettor, except very small ones.

 

If fuel injection is involved, then filtering requirements needs to be tightened substantially to take into account tight tolerances of critical moving parts that are operating at high pressure.

 

A useful quick guide is in the article below, as to the dimensions of particles, micron sizes relating to everyday products, etc...

 

https://gacc.nifc.gov/nrcc/dispatch/equipment_supplies/agree-contract/forms/MicronMesh.pdf

[skippydiesel]

Thanks Onetrack - very well articulated.

 

One point- I don't have to guess/speculate on the fuel "cleanliness" required. Rotax have a specification for this (see above comment from me) "filter with mesh size 0.1 mm (70–100µ) " so 120 micron is a bit too course. I will aim for about 50-74 micron in my final/last filter in the system

 

[facthunter]

The effective area of the filter mesh is important and also sediments of fine particles can form when/where the system is not agitated.. Fuel bowls and down then up bends. Flush at high flow occasionally.. Microbes in fuel can cause filter blockages especially avtur and diesel. Avtur has stuff in it to  kill the microbes and it's not good for people either. . Nev