Van's Air Force
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Fuel Selector Valve - Both Tanks Option?
- Thread starter jsharkey
- Start date
Kevin Horton
Well Known Member
Anyone who can't understand why a Both selection wouldn't work in an RV should do a simple experiment. Buy some clear plastic tubing and a T fitting. Put a piece of tubing on each end of the T. Put two ends in glasses of water, and suck on the other end. This is the situation when both tanks have fuel. Now, empty the water out of one of the glasses and try again. Now all you suck is the air from the empty glass.
On a high wing, gravity feed fuel system, a Both position can improve safety, because you don't have the risk of engine failure if you forget to change change tanks. On a low wing, suction feed fuel system, a Both position would decrease safety, as the engine would quit when either tank ran dry. Yes, you could simply change to the tank with fuel to get a restart, but first you have to figure out which tank is the good one. At least with a Left - Right fuel selector, if you forget to change tanks it is obvious which tank you need to switch to.
On a high wing, gravity feed fuel system, a Both position can improve safety, because you don't have the risk of engine failure if you forget to change change tanks. On a low wing, suction feed fuel system, a Both position would decrease safety, as the engine would quit when either tank ran dry. Yes, you could simply change to the tank with fuel to get a restart, but first you have to figure out which tank is the good one. At least with a Left - Right fuel selector, if you forget to change tanks it is obvious which tank you need to switch to.
Greg Arehart
Well Known Member
Along those same lines, I dislike the Vans fuel selector because it doesn't have a clear "stop" at each position (sure, its there, but only if one is very sensitive). Seems to me this might easily allow one to put the valve in a slightly "off" position. Of course, it would probably be noticeable as soon as the engine sputtered and stopped but... I have been considering a couple of alternatives. One is to put a manual stop just CCW of the L tank position and another just R of the R tank position, thereby allowing me to turn the valve to exactly the correct position. Downside is that there would not be an "off" position. An alternative is to put a single on-off valve on each tank line, with a T just engine-side of the valves. This would necessitate turning two valves to change tanks, plus an additional connection (i.e., leak potential), but at least I could be certain of valve positioning. Comments on other aspects of this that I have overlooked would be welcome, including other options for the fuel selection.
greg
greg
FrankK90989
Well Known Member
The fix
Place a thin clean mark on the valve stem and one for each position (L-R) on the plate and just line them up, no need to feel.
Place a thin clean mark on the valve stem and one for each position (L-R) on the plate and just line them up, no need to feel.
L.Adamson
Well Known Member
Either exact markings, as mentioned. Or just get an Andair valve, and problems will all be solved, including the "off" position.
L.Adamson --- RV6A/Andair fuel valve
Greg Arehart
Well Known Member
Mel, so what are people doing for fuel valves?
greg
greg
L.Adamson
Well Known Member
Andair from Van's or other sources.
Note; Link didn't go where I wanted. Look under cockpit and airframe accesseries. Then fuel valves.
http://www.vansaircraft.com/cgi-bin/catalog.cgi?ident=1195402699-94-
Most people opt for the Andair valves.
Norman CYYJ
Well Known Member
If you are wanting a positive mechanical stop place a bolt next to the on positions which will stop the handle from turning any further. If you want to go to the off position make the bolt stops spring loaded so that you will have to push them down to get past them.
Stock valve = Volkswagon... it works
Andair = Rolls Royce... it works and is a marvel of art and engineering
Worth it ? If you hold a stock valve in one hand, Andair in the other, then set the stock valve down and use the free hand to move the Andair selector, you will buy one.
Over the life of one engine run (2000 hrs), $ 100,000.00 worth of gas will go through the valve
Andair = Rolls Royce... it works and is a marvel of art and engineering
Worth it ? If you hold a stock valve in one hand, Andair in the other, then set the stock valve down and use the free hand to move the Andair selector, you will buy one.
Over the life of one engine run (2000 hrs), $ 100,000.00 worth of gas will go through the valve
pierre smith
Well Known Member
Van's
I have Van's. A mark corresponding to each tank, 300 hours now....you can clearly feel it "click".
My 02.
I have Van's. A mark corresponding to each tank, 300 hours now....you can clearly feel it "click".
My 02.
Shockwave
Well Known Member
Not to spoil the party, but the Beech Skipper does indeed have a Both fuel selection. The schematic in the POH seems to indicate that both wing tanks feed a larger diameter tube which then runs to the fuel selector valve. I'm guessing it operates somewhat like a header tank. There are check valves at the exit of the wing tanks, and a fuel tank vent that runs between both tanks.
I did my first 20 hours of instruction in the Skipper and don't ever recall having a heavy wing or fuel imbalance problems.
I did my first 20 hours of instruction in the Skipper and don't ever recall having a heavy wing or fuel imbalance problems.
It is just a matter of plumbing
I use two of Van's valves for my fuel control system and after ~400 hours have had no problem. I do have index marks on the console for general orientation and I feel for the detent when selecting a new tank. My valves have 4 inlet ports and one outlet port. I use them to allow individual selection of four independent fuel tanks in a simple fool proof operational manner that is too complex in implementation to describe. I cannot imagine myself ever wanting to be in a situation where when everything gets quite except for wind noise that I don't have another tank to switch to but you can plumb the lines through "T"s and tubes to use one port for both in level flight, one for right one for left and one (plugged) for off. When you get down to the bottom though, the tank that goes empty first will not be known the engine will stop while you still have usuable fuel on board and you will get very tense switching the valve trying to find a tank with fuel left in it, turning on the aux. pump and applying carb heat. The problem is, it takes several seconds for fuel to be pumped to the engine and for it to restart. The chances are you will not be patient enough to leave it on a tank with fuel long enough to restart or you will leave it on the empty tank trying to be patient enough for it to restart. This is a stressful time. If you engine stops but the prop is turning it will restart if you select a single tank and it has fuel but it may take 5 seconds or so.
Bob Axsom
I use two of Van's valves for my fuel control system and after ~400 hours have had no problem. I do have index marks on the console for general orientation and I feel for the detent when selecting a new tank. My valves have 4 inlet ports and one outlet port. I use them to allow individual selection of four independent fuel tanks in a simple fool proof operational manner that is too complex in implementation to describe. I cannot imagine myself ever wanting to be in a situation where when everything gets quite except for wind noise that I don't have another tank to switch to but you can plumb the lines through "T"s and tubes to use one port for both in level flight, one for right one for left and one (plugged) for off. When you get down to the bottom though, the tank that goes empty first will not be known the engine will stop while you still have usuable fuel on board and you will get very tense switching the valve trying to find a tank with fuel left in it, turning on the aux. pump and applying carb heat. The problem is, it takes several seconds for fuel to be pumped to the engine and for it to restart. The chances are you will not be patient enough to leave it on a tank with fuel long enough to restart or you will leave it on the empty tank trying to be patient enough for it to restart. This is a stressful time. If you engine stops but the prop is turning it will restart if you select a single tank and it has fuel but it may take 5 seconds or so.
Bob Axsom
alpinelakespilot2000
Well Known Member
My stock Van's valve (c. 2005) has very clear "stops" at each position. There is no way to miss whether or not the lever is in one of the two on positions versus one of the two off positions. Might be that you just got a bad one or I got a really good one?
