Gascolators in hand, versus Filters in the bush?

One of the joys of working on a really well planned Project is the little surprises you run into all the time.

It's time to get into fuel system planning and plumbing, but of course the previous builder (Kent Scherm, Ontario CA) got there before me. The Fuel pump location is ready for me, but there was no fuel filter plumbing ready at the standard location. Instead, since it was a Canadian project, he went with Gascolators.
So, I have two Andair GAS375 gascolators still in the original packaging already in hand. Given that, and I understand fuel filters are somewhat preferred for injected systems, should I just stick with gascolators in each wing root, or put them back on the shelf and go with inline filters?

Depends on your preferences really.
-If you plan on going with a carbureted or mechanically fuel injection equipped engine, the gascolators (which you already have) mounted near the wing roots are still a valid choice, you could also double up & place fuel filters somewhere later in the delivery circuit if you want.
-If you are going with a SDS or EFII electronically injected system, than you would want to go with filters (note each mfgr suggest specific in line filters so if this is your route, check with them for the filters). You still could mount gascolators near the wing roots (low fuel pressure area) if you want to check & purge water during your walk around prior to flight. In high pressure sections (after the pumps) you definitely want to use filters (gascolators tend to leak under pressure) to protect the system from particulate.

Yes, the plumbing already installed (which, of course I could change, if necessary) bypasses the "standard" cockpit floor fuel filter which would have been just upstream of the "standard" fuel pump location. So, I'm talking about low pressure locations at the wing root. There will be mechanical fuel injection as well as an electrical boost pump.

Given all of that, and with two brand new gascolators in hand, do I simply use them or purchase two inline fuel filters?

If I have the standard fuel drains on the tanks, will I also need to drain fuel/water from the wing root gascolators on walkaround? Seems redundant.

claycookiemonster said:

SNIP

Given all of that, and with two brand new gascolators in hand, do I simply use them or purchase two inline fuel filters?

If I have the standard fuel drains on the tanks, will I also need to drain fuel/water from the wing root gascolators on walkaround? Seems redundant.

Click to expand...

First step is to make sure the filter element in the gascolator is appropriate for your fuel injection system. If so, then gascolator or filter becomes a matter of preference.

If you do mount these in the wing root, you will need to cut a small hole in the wing intersection to sump the gascolator. There is no reason not to keep the wing sump valve as is.

Carl

Well, lowest point in your system is the tank drains for purging water... doesn't make much sense to install gascolators in your system if the fuel/water must run up hill to be collected to be drained out again.

We in Canada have to put up with this nonsense of gascolators... no matter how much logic suggests it doesn't work in our planes....

What Ralph said, the wing sump is a gascolator and there is a coarse screen on my tank pickups and a filter in the tunnel. I have thought about adding a gascolator on the firewall (carb O-540) but don’t see the point.

Am I missing anything?

Just heard back from Aero Sport Power and they said that filters vs gascolators was an airframe issue and they don't get involved. Interesting. So, I've still got the two gascolators the original builder bought, and the plumbing remains to be done either way. Both options will be done at the wing root before the boost pump.

Leaving aside the ability of a gascolator to collect water out of the fuel as it passes, are gascolators and in line filters equivalent purely in terms of filtration? Any differences when the time comes to change them, or clean them?

claycookiemonster said:

SNIP
Leaving aside the ability of a gascolator to collect water out of the fuel as it passes, are gascolators and in line filters equivalent purely in terms of filtration? Any differences when the time comes to change them, or clean them?

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Nope - gascolator do not strip water out of fuel as it passes. The point of a gascolator is if it is mounted in the low point of the fuel system, gravity (over time) will collect the water out of the tank that can get to the gascolator. This is why they make little sense in low wing airplanes where the gascolator is not mounted lower that the lowest point in the tank. Water will not run up hill to be collected. Look at how the gascolator is mounted on any high wing plane.

The gascolator is not like a cyclone fluid separator. There is no mechanical action on the fuel passing through it.

If you use it as a filter, just verify the filter size meets the requirement of your carb/fuel injection system.

Carl

Side note - I like the AirFlow Performance in line fuel filter as it has a lot of surface area. If would take a massive amount of crud getting into the tank to block the filter between condition inspections.

My .02!

Sell the gascolators to the first antique tractor fan you come across and don’t think about them ever again!

Wheel.... Re-invent.... Follow plans. You have two tank sumps? You put clean filtered 100LL in? Airplane hangered? Sump tanks 1st flight and after refuel. The gascolator is after L&R selector and Electric pump for Carb. Gascolator has a filter and could collect water (dispite comments you can pump water). If fuel is overly contaminated nothing and you go flying you are in trouble. Sump tanks and keep water and dirt out.

If you have FI then follow manufacture recommended fuel system. I know some FI systems call for filters for each tank before fuel selector.

Thanks for all the loaned grey matter, guys. Fuel filters, here I come!

So, now exploring the twin wing root filter route. This project was intended to use the standard Van's supplied Airflow Performance pump, so the mounting will be easy. The nutplates are already installed. Looking at those pumps, it seems there is a filter included with the pump, am I right?

So, big picture, I'll be installing an inline filter between each tank and the electronic fuel pump, and that pump will have it's own filter. All good, but wasn't part of the reason to put fuel filters in the wing root so I could avoid the mess of cleaning a filter in the cockpit?

This might be what you are looking for. Or contact Tom at TS Flightlines for a more elegant solution.

claycookiemonster said:

So, now exploring the twin wing root filter route. This project was intended to use the standard Van's supplied Airflow Performance pump, so the mounting will be easy. The nutplates are already installed. Looking at those pumps, it seems there is a filter included with the pump, am I right?

So, big picture, I'll be installing an inline filter between each tank and the electronic fuel pump, and that pump will have it's own filter. All good, but wasn't part of the reason to put fuel filters in the wing root so I could avoid the mess of cleaning a filter in the cockpit?

Click to expand...

Pre and post filters are pretty standard for electric pumps in my automotive/offroading experience. The prefilter protects the pump from gunk in your fuel. The post filter protects the engine if the pump ever decides to grenade itself. You can put the post filter FWF if you don't want to deal with cleaning it in the cockpit, but then you may run into heat soak issues, etc.

Got it. Twoop.