For years I have wondered why the recommendation is to place the gascolator at the lowest point in the fuel system. I can not see how it makes any difference what so ever. If you have a scientific explanation, please share...
The answer is that water seeks the lowest point and in flight, water can be suspended in tiny blobs within your fuel. The goal is to have it collect in the Gascolator and not in the carb bowl.
For years I have wondered why the recommendation is to place the gascolator at the lowest point in the fuel system. I can not see how it makes any difference what so ever. If you have a scientific explanation, please share...
My contention is that the gascolator will do this equally well mounted on a 6' pole above the plane. Maybe in a high-wing gravity fed system with no fuel selector valve there could be an advantage to having it at the low point; but only if the fuel pick-up is lower than the fuel tank sump, which I don't think exists. Otherwise the gascolator should do it's job equally well no mater where it is mounted. There is nowhere in the fuel system to introduce water other than the fuel tanks, and in an RV the fuel must go uphill before it goes to the engine or the gascolator.
My contention is that the gascolator will do this equally well mounted on a 6' pole above the plane. Maybe in a high-wing gravity fed system with no fuel selector valve there could be an advantage to having it at the low point; but only if the fuel pick-up is lower than the fuel tank sump, which I don't think exists. Otherwise the gascolator should do it's job equally well no mater where it is mounted. There is nowhere in the fuel system to introduce water other than the fuel tanks, and in an RV the fuel must go uphill before it goes to the engine or the gascolator.
If nothing else; having the gascolator at the bottom of the firewall provides a realistic and clean location to access it and drain it. For that reason i'm not sure i'd want it anywhere else.
How and how often do you drain the gascolator? I was told at an Oshkosh workshop it should be done before each flight, like a fuel sump. I'm building a RV-7A and it seems that with the gascolator mounted on the firewall, one would have to either reach up through the lower cowl exhaust opening--very awkward at best--or have a special access door in the cowl for this purpose.