Fuel Polishing again.
 

I am assembling my posihing system. Not clear whether it is better
to put the pump on the pressure side or the vacuum side. Having no
filter on the intake of the pump seems risky. I am using a 2 stage
approach. maybe putting the filter between the filters is an option.

Doug
s/v Callista

Fuel Polishing again.
 

Racor strongly recommends that filters be operated under vacuum rather
than pressure. I believe the idea being safety. Better for a leak to
pull in air than spray fuel.

Doug Dotson wrote:
I am assembling my posihing system. Not clear whether it is better
to put the pump on the pressure side or the vacuum side. Having no
filter on the intake of the pump seems risky. I am using a 2 stage
approach. maybe putting the filter between the filters is an option.

Doug
s/v Callista



--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Fuel Polishing again.
 

Racor strongly recommends that filters be operated under vacuum rather
than pressure. I believe the idea being safety. Better for a leak to
pull in air than spray fuel.

Doug Dotson wrote:
I am assembling my posihing system. Not clear whether it is better
to put the pump on the pressure side or the vacuum side. Having no
filter on the intake of the pump seems risky. I am using a 2 stage
approach. maybe putting the filter between the filters is an option.

Doug
s/v Callista



--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Fuel Polishing again.
 

Interesting. More tradeoffs. I have been told (by Rich H) that filters
last longer in pressure mode. I'm not using Raycor but I'm sure the
issues are similar. I've also been advised that operating the engine
fuel system in pressure mode is better because a leak will not
kill the engine, just leak some fuel. I'd never consider such an
approach with a gasoline engine, but with a diesel the risk seems
acceptable. I had a minor leak this summer and enfed up with a
couple gallons of bilge in the catch pan under the engine. No real
danger although a pain to clean up.

Doug
s/v Callista

"Glenn Ashmore" wrote in message
news:rL%Kb.29544$JD6.12079@lakeread04...
Racor strongly recommends that filters be operated under vacuum rather
than pressure. I believe the idea being safety. Better for a leak to
pull in air than spray fuel.

Doug Dotson wrote:
I am assembling my posihing system. Not clear whether it is better
to put the pump on the pressure side or the vacuum side. Having no
filter on the intake of the pump seems risky. I am using a 2 stage
approach. maybe putting the filter between the filters is an option.

Doug
s/v Callista



--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Fuel Polishing again.
 

Interesting. More tradeoffs. I have been told (by Rich H) that filters
last longer in pressure mode. I'm not using Raycor but I'm sure the
issues are similar. I've also been advised that operating the engine
fuel system in pressure mode is better because a leak will not
kill the engine, just leak some fuel. I'd never consider such an
approach with a gasoline engine, but with a diesel the risk seems
acceptable. I had a minor leak this summer and enfed up with a
couple gallons of bilge in the catch pan under the engine. No real
danger although a pain to clean up.

Doug
s/v Callista

"Glenn Ashmore" wrote in message
news:rL%Kb.29544$JD6.12079@lakeread04...
Racor strongly recommends that filters be operated under vacuum rather
than pressure. I believe the idea being safety. Better for a leak to
pull in air than spray fuel.

Doug Dotson wrote:
I am assembling my posihing system. Not clear whether it is better
to put the pump on the pressure side or the vacuum side. Having no
filter on the intake of the pump seems risky. I am using a 2 stage
approach. maybe putting the filter between the filters is an option.

Doug
s/v Callista



--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Fuel Polishing again.
 

On Wed, 7 Jan 2004 17:16:45 -0500, "Doug Dotson"
wrote:

I am assembling my posihing system. Not clear whether it is better
to put the pump on the pressure side or the vacuum side. Having no
filter on the intake of the pump seems risky. I am using a 2 stage
approach. maybe putting the filter between the filters is an option.

Probably better to have the pump suck clean fuel through the filters
than force dirty fuel through.

Steve

Fuel Polishing again.
 

On Wed, 7 Jan 2004 17:16:45 -0500, "Doug Dotson"
wrote:

I am assembling my posihing system. Not clear whether it is better
to put the pump on the pressure side or the vacuum side. Having no
filter on the intake of the pump seems risky. I am using a 2 stage
approach. maybe putting the filter between the filters is an option.

Probably better to have the pump suck clean fuel through the filters
than force dirty fuel through.

Steve

Fuel Polishing again.
 

Doug Dotson wrote:
I am assembling my posihing system. Not clear whether it is better
to put the pump on the pressure side or the vacuum side. Having no
filter on the intake of the pump seems risky. I am using a 2 stage
approach. maybe putting the filter between the filters is an option.

You want to avoid having the pump act as an homogenizer. If
the pump takes suction directly from the tank it will
thoroughly mix all the water and crud that you want to
filter out. This makes it much more difficult to remove in
the filters.

The Racors operate best on the suction side because the
separator section of the filter will, when it receives one,
deposit a clean slug of water in the bowl rather than clog
the filter media with an emulsion created by the pump.

Rick

Fuel Polishing again.
 

Doug Dotson wrote:
I am assembling my posihing system. Not clear whether it is better
to put the pump on the pressure side or the vacuum side. Having no
filter on the intake of the pump seems risky. I am using a 2 stage
approach. maybe putting the filter between the filters is an option.

You want to avoid having the pump act as an homogenizer. If
the pump takes suction directly from the tank it will
thoroughly mix all the water and crud that you want to
filter out. This makes it much more difficult to remove in
the filters.

The Racors operate best on the suction side because the
separator section of the filter will, when it receives one,
deposit a clean slug of water in the bowl rather than clog
the filter media with an emulsion created by the pump.

Rick

Fuel Polishing again.
 

That's why one of my thoughts is to put the pump between
the filters. 10 uM upstream, 1 uM downstream.

Doug
s/v Callista

"Steven Shelikoff" wrote in message
...
On Wed, 7 Jan 2004 17:16:45 -0500, "Doug Dotson"
wrote:

I am assembling my posihing system. Not clear whether it is better
to put the pump on the pressure side or the vacuum side. Having no
filter on the intake of the pump seems risky. I am using a 2 stage
approach. maybe putting the filter between the filters is an option.

Probably better to have the pump suck clean fuel through the filters
than force dirty fuel through.

Steve