Fuel selector or two check valves?

Instead of using a left/right fuel selector, could I use two check valves
and connect the two tanks into a single feed?

[LTANK]---|-----T-----|-----[RTANK]

Where | and | are the check valves and 'T' is a T-connector towards the
header tank.
The check valves prevent fuel moving from one tank to the other. Any pro's,
con's or thoughts?

Rob

"Rob Turk" wrote in message
news:SN6we.366$in3.124@amstwist00...
Instead of using a left/right fuel selector, could I use two check valves
and connect the two tanks into a single feed?

[LTANK]---|-----T-----|-----[RTANK]

Where | and | are the check valves and 'T' is a T-connector towards the
header tank.
The check valves prevent fuel moving from one tank to the other. Any
pro's,
con's or thoughts?

I'd want more control over the actual fuel usage than a check valve will
give me. The selector valve will allow you to use fuel from the 'heavy side'
to properly level out- check valves will not allow this. Then you can leave
the selector valve on 'both' for normal conditions.

"Edgar" wrote in message
...

"Rob Turk" wrote in message
news:SN6we.366$in3.124@amstwist00...
Instead of using a left/right fuel selector, could I use two check valves
and connect the two tanks into a single feed?

[LTANK]---|-----T-----|-----[RTANK]

Where | and | are the check valves and 'T' is a T-connector towards
the
header tank.
The check valves prevent fuel moving from one tank to the other. Any
pro's,
con's or thoughts?

I'd want more control over the actual fuel usage than a check valve will
give me. The selector valve will allow you to use fuel from the 'heavy
side'
to properly level out- check valves will not allow this. Then you can
leave
the selector valve on 'both' for normal conditions.


Wouldn't gravity take care of leveling the two tanks? That way there
wouldn't be a heavy side. My assumption is that the fullest one will create
more pressure, causing it to level automatically. Wrong assumption?!? This
is on a high-wing plane by the way..

Rob

Wouldn't gravity take care of leveling the two tanks? That way there
wouldn't be a heavy side. My assumption is that the fullest one will create
more pressure, causing it to level automatically. Wrong assumption?!? This
is on a high-wing plane by the way..

Rob


I think that your tanks will not feed evenly because of little
differences in the way the lines run and venting. You will also lose
the ability to run one tank dry to extend your range. On my murphy
rebel one tank feeds a lot faster than the other one when I'm running
on both.

Drew Dalgleish wrote:

Wouldn't gravity take care of leveling the two tanks? That way there
wouldn't be a heavy side. My assumption is that the fullest one will create
more pressure, causing it to level automatically. Wrong assumption?!? This
is on a high-wing plane by the way..

Rob


I think that your tanks will not feed evenly because of little
differences in the way the lines run and venting. You will also lose
the ability to run one tank dry to extend your range. On my murphy
rebel one tank feeds a lot faster than the other one when I'm running
on both.


Very dependent on how far below the tank outlet the two lines/valve
connects the two feed lines,,,,,,,,,,

a connection that is level with the tank outlets will very likely have
trouble feeding both tanks evenly,

a much lower connection won't care,,,,,,,,,
--
Mark Smith
Tri-State Kite Sales
1121 N Locust St
Mt Vernon, IN 47620
1-812-838-6351
http://www.trikite.com

On Tue, 28 Jun 2005 12:54:20 GMT, Mark Smith wrote:

Drew Dalgleish wrote:

Wouldn't gravity take care of leveling the two tanks? That way there
wouldn't be a heavy side. My assumption is that the fullest one will create
more pressure, causing it to level automatically. Wrong assumption?!? This
is on a high-wing plane by the way..

Rob


I think that your tanks will not feed evenly because of little
differences in the way the lines run and venting. You will also lose
the ability to run one tank dry to extend your range. On my murphy
rebel one tank feeds a lot faster than the other one when I'm running
on both.


Very dependent on how far below the tank outlet the two lines/valve
connects the two feed lines,,,,,,,,,,

a connection that is level with the tank outlets will very likely have
trouble feeding both tanks evenly,

a much lower connection won't care,,,,,,,,,

that may usually be the case but on my plane the connection is at the
firewall just ahead of the gascolator. thats almost 3' difference in
height. When I did my fuel flow test the tanks flowed the same amount.



Mark Smith
Tri-State Kite Sales
1121 N Locust St
Mt Vernon, IN 47620
1-812-838-6351
http://www.trikite.com

Is the fuel above or below the engine (high wing or low wing?)

it IS possible in a low wing configuration for one tank to completely
drain and then suck air.

The answer to that is to use a sump or gravity fed header tank.

The Velocity plans call for two strake mounted tanks, draining into a
single sump, from there the fuel is fed to the engine. In practice the
two strake tanks and sump function as a single fuel tank. The check
valve isnt necessary.

Dave

Rob Turk wrote:
Instead of using a left/right fuel selector, could I use two check valves
and connect the two tanks into a single feed?

[LTANK]---|-----T-----|-----[RTANK]

Where | and | are the check valves and 'T' is a T-connector towards the
header tank.
The check valves prevent fuel moving from one tank to the other. Any pro's,
con's or thoughts?

Rob

How would you shut off the fuel? Let's say in the case of fire. Al


"Rob Turk" wrote in message
news:SN6we.366$in3.124@amstwist00...
Instead of using a left/right fuel selector, could I use two check valves
and connect the two tanks into a single feed?

[LTANK]---|-----T-----|-----[RTANK]

Where | and | are the check valves and 'T' is a T-connector towards the
header tank.
The check valves prevent fuel moving from one tank to the other. Any
pro's, con's or thoughts?

Rob

Drew Dalgleish wrote:

On Tue, 28 Jun 2005 12:54:20 GMT, Mark Smith wrote:

Drew Dalgleish wrote:

Wouldn't gravity take care of leveling the two tanks? That way there
wouldn't be a heavy side. My assumption is that the fullest one will create
more pressure, causing it to level automatically. Wrong assumption?!? This
is on a high-wing plane by the way..

Rob


I think that your tanks will not feed evenly because of little
differences in the way the lines run and venting. You will also lose
the ability to run one tank dry to extend your range. On my murphy
rebel one tank feeds a lot faster than the other one when I'm running
on both.


Very dependent on how far below the tank outlet the two lines/valve
connects the two feed lines,,,,,,,,,,

a connection that is level with the tank outlets will very likely have
trouble feeding both tanks evenly,

a much lower connection won't care,,,,,,,,,

that may usually be the case but on my plane the connection is at the
firewall just ahead of the gascolator. thats almost 3' difference in
height. When I did my fuel flow test the tanks flowed the same amount.



I'd bet mine would too, on the ground,

but in the air, they were several inches different, and with a tank that
is pretty thin, it is a bunch of fuel, or air, since the pump will suck
air from the empty tank rather than fuel from the partially full one,

I solved it by installing two small forward pointing tubes that mount on
the caps,,,,
--
Mark Smith
Tri-State Kite Sales
1121 N Locust St
Mt Vernon, IN 47620
1-812-838-6351
http://www.trikite.com

"Al" wrote in message
news:1119973229.7b47c562c0536a3cc6ea1419507bddbe@t eranews...
How would you shut off the fuel? Let's say in the case of fire. Al



The full picture is a bit more complex (isn't it always...)

This is a high-wing plane (Rans S6S). Both main tanks have breather pipes to
pressurise the tanks during flight. The fuel lines from the tanks flow into
separate entries of a fuel buffer tank (approx 1.5 Gallon) placed low, below
the luggage compartment. From the buffer tank a single feed goes through a
Facet pump (just in case), then through the fuel filter to a shut-off valve
near the firewall, within easy reach of the pilot. Then through the firewall
into a gascolator. Output of the gascolator goes to the mechanical pump on
the Jabiru engine, then to the carburettor.

The overflow of the gascolator goes through a check valve, then through a
return line into the buffer tank.

What I'm trying to determine is if I should use separate cut-off valves in
the lines from the main tanks to the buffer, or that I can use check valves
instead.

Rob