I was thinking about putting 3/8 vent line
in my header tank (under construction) but the opposite question is --- would
it over pressure the tank?
Bob Mitchell
Lancair 320 sloooo build kit
From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Sky2high@aol.com
Sent: Tuesday, November 25, 2008
7:00 AM
To: lml@lancaironline.net
Subject: [LML] Re: 360 Fuel Vent
Assuming all kinds of things and using
pipe flow calculator for a gas known as air:
If your engine is using 15 gal/hr = 2 cu
ft/hr = .0335 cfm
Suppose the inside diameter of 1/4"
tubing is .156", the pressure of the air at the vent is .7 psi (about 200
kts) and the temp is 31F, then the air is traveling in the tube at 3 Kts.
"So What?" You might ask.
OK then, take a gallon jug, fit a 3/8
inch tube (engine pump fuel line size?) at one end and a quarter inch
tube at the other end (vent line). Use a good
sealing putty. Fill the jug with water. Let the water drain
out the 3/8 tube and time it. If it drains in 3 minutes or less (1
gal/4 min = 15 gals/hr., 1 gal/3 min = 20 gph), the vent is large enough.
That's just using gravity - without assistance from the engine pump
or the vent pressure and 100LL may be less viscous.
PS Let us in on the results.
In a message dated 11/24/2008 10:01:34
P.M. Central Standard Time, cassutt@windstream.net writes:
I am not using the header tank in my 360
and have installed 1/4" od tubing as the vent for each wing tank. My old
SB manual says nothing about fuel vent size even with the header and what
published updates there are for the extended bay don't have a size listed
either. Is this big enough dia. for pulling fuel straight from the wings
or should it be larger? What have others done.
Eric Demaray
360 SB
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