REFLECTOR: Fuel venting issue

[Alex Balic]

The one that I have is the high dollar Andair unit- has a decent cracking
pressure (spring) in there- it does not leak in the reverse direction
(balloon test) although they do make a model with a designed in internal
metering orifice that would, and as long as the normal vent is working
-pressurizing the tanks- it would be held closed even without a spring- I
also asked Andair if it can be used for a vent line check, and they
concurred that it can be used for that purpose,

Even if  an improper vent setup put negative pressure on the tanks, the
valve would either remain closed due to the higher cracking pressure or
allow air to flow from the cabin to the normal vent exit- I can not see any
way that it would allow either fuel or vapor into the cabin- but would
certainly like to hear from anyone using a check valve that has had this
problem. 

 

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From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Scott Derrick
Sent: Sunday, July 01, 2007 8:35 PM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Fuel venting issue

 

these valves are made for liquid.  one way valves can seep a bit, and you
would never know, except in this case... its only held closed by a very
small spring.

I'm trying to think of another plane that has a fuel vent open to the cabin
and can't.  The failure mode of  this valve is potentially  catastrophic! 

Anybody know of any certified or experimental plane that has this
configuration? 

Was this added because somebody crashed? 

Can Scott Baker explain the reasoning behind this change to the plans and
why Velocity thinks this is a safe thing to do?

Scott

Brett Ferrell wrote: 

Then it's a good thing it's not open to the cabin.  The check valve only
allows air from the cabin into the tanks....

B

Scott Derrick wrote: 

I have a hard time feeling good about having a fuel vent line open to the
interior of the cabin...

Scott

Alex Balic wrote: 

The check valve is located inside the plane and above the level of the fuel
in the tanks (right up at the roof- it T's into the vent system, so fi the
external vent fails, it will open and allow air into the tanks from the
cabin- but not let fuel/fumes out into the cabin.
 
-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of David Staten
Sent: Sunday, July 01, 2007 12:49 PM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Fuel venting issue
 
If the check valve is on the same line that is theoretically blocked by 
ice or mud, how is it able to prevent ANYTHING? An obstructed vent is an 
obstructed vent.
 
Dave
 
Brett Ferrell wrote:
 
  

The check valve is actually there to prevent tank collapse should the 
vent line become blocked (by say a mud-dauber or ice accumulation).  
I've seen a 15,000 gallon steel tank collapse by a plugged vent, and 
it's not pretty...
 
B
 
Scott Derrick wrot





 





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