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To: flyrotary@lancaironline.net
Date: Tue, 20 Dec 2005 16:49:54 -0800
Subject: Re: [FlyRotary] Re: Fuel filter selection
Message-ID: <20051220.164959.3260.10.alwick@juno.com>
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From: al p Wick <alwick@juno.com>


On Tue, 20 Dec 2005 18:22:08 -0500 Ernest Christley
<echristley@nc.rr.com> writes:
> al p, you've broken the issue down, so may I pick on your analysis?  
 
I place great value in questioning stuff like this. Definitely fire away.


> Debris killing the pump. 
> You throw out a number ... 1 every 500 hours.  That's well and good, 
> but 
> we're talking about debris in the pump.  The only place that I see the 
> debris coming from is the tank. 

If we analyzed the actual causes for tank contamination, I'm confident
90% are caused my construction debris remaining in tank. It's been the
cause for all of the canards I looked into. Builders use vacuum cleaner
to remove debris, but the debris is actually forced to the tank corners
by the air rushing into the tank. Only a small portion get vacuumed up.

 The most likely scenario is crappy 
> gas 
> from a bad station, or a windstorm at the beach.   Losing power has the
same 
> effect, 
> regardless of why, so I'd make the EFFECT component the same as you 
> set 
> for vapor lock, 6.  You might notice the bad gas; you might not.  
> So, 
> the risk component can be set as high as you did for vapor lock, 7.  
> My 
> guesstimate is that suck trash into your pumps will kill you as fast 
> as 
> vapor lock.

Maybe I misunderstand how you operate your pumps. I use only 1 pump. If
second pump is NOT running, it can not clog up with debris. It takes time
for debris, particularly if you use the inlet sock I use. That thing near
impossible to clog up.
But by all means, use your own numbers. You are always better off
converting your ideas to numbers, putting them on paper or spreadsheet. I
clarifies perspective. Great tool for decision making.


> 
> Water damaging injectors.
> You got me there.  I would assume that the ratio to gas would 
> determine 
> if the engine kept running at all, but it no way do I see it as 
> being a 
> good thing.  Would the pump even be able to continue pumping after 
> it is 
> all 'frothed' up?   ie, would this be a sort of vapor lock in 
> itself?  
> Call it froth lock?
> 
> Vapor lock caused by pressure drop:
> The PRM-81794 High Performance Filter Head is rated for 25GPM.  
> Perma-Cool's website recommends its use for a filling station.   
> http://www.perma-cool.com/Catalog/Cat_page26.html  I think it would 
> 
> laugh at our measely 25GPH fuel flows, adding no measurable 
> restriction. 

Very measurable. Measure it!! 


 >I assume it does this in conjunction with the fine 
> filtering by using an extremely large filtering area (but that is 
> just a guess).  

Don't guess, these are life risking decisions. Measure measure.


> I agree with your vapor lock risk assessment.  They are as good as 
> any 
> I've seen pulled from thin air.  But I think you greatly 
> underestimate 
> the risk, effects and results of bad fuel.  

Nothing wrong with you arriving at different conclusion. I have to admit
I have a hard time following all of your logic, but that's fine. It's
great that we can each take our path of choice.


-al wick
Artificial intelligence in cockpit, Cozy IV powered by stock Subaru 2.5
N9032U 200+ hours on engine/airframe from Portland, Oregon
Prop construct, Subaru install, Risk assessment, Glass panel design info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html