On Fri, 09 Jan 2004 14:47:50 GMT, Rich Hampel
wrote:

Another good reason NOT to pull vacuum on fuels and other volitile
liquids is that if the vacuum exceeds the vapor pressure of the fluid
the liquid with boil (flash) or you will separate out the lighter
fractions (lighter weight hydrocarbons). If youve ever had a gasoline
that had 'vapor-lock' problems you'll understand this phenomenom. I
dont have by me at this time a listing of the vapor pressure range of

That's pretty much self regulating in this case. I.e., if you had a
pump that was strong enough to create a vapor lock due to a very high
vacuum, it would stop pumping and the vacuum would decrease and the
vapor lock would be cured.

But then again, if you had so much of a pressure difference on most of
the filters we're talking about here that the fuel boils due to the
vacuum of being drawn through the filter, it's time to change the
element anyway. Either that or the pump is too strong and will destroy
the filter.

Steve

On Sat, 10 Jan 2004 05:40:18 GMT, Jere Lull wrote:

In article ,
(Steven Shelikoff) wrote:

On Fri, 09 Jan 2004 07:51:04 GMT, Jere Lull wrote:

In article ,
Rick wrote:

The element cannot possibly know what mechanism is used to
establish fluid flow through the filter. The only thing the
filter sees is rate of flow and as it clogs, differential.
Anyone who claims otherwise is ignoring some other factor or
talking BS.

ONLY if you're only looking at the filter.

We are only looking at the filter, not taking into account the casing,
plumbing, etc.

Steve

I believe that the case is a pretty major component to ignore in a
polishing system. A case designed for partial vacuum may not properly
handle whatever pressure the pump can deliver. If the company says "only
suction", I suspect it wasn't designed for pressure.

When looking at the entire fuel polishing system, we're not ignoring the
case. When looking strictly at the difference in the performance of the
filter media, by definition we are ignoring the case. My question is
why does it matter strictly to the performance of the filter media
whether fuel is being pushed through by a pump or pushed through by
atmospheric pressure?

Getting back to the filter alone: Since I believe most pumps can "push"
better than they can "pull", we should also consider the maximum
differential the filter can handle before it tears or otherwise breaks
down. Rich mentioned a design limit of 6" vacuum (about 3 psi?) What can
these pumps deliver?

Typical of the pumps used in this application is the Walbro 6802. I
don't see the spec on vacuum for it on the web but it delivers 7 psi
pressure so the vacuum is probably somewhat less. I do have the manual
on the boat, but I'm not going down there anytime soom. In application,
I haven't measured more than about 5 psi of vacuum before I changed
elements. The Racors have no problem with 7 psi vacuum or pressure.

Steve

On Sat, 10 Jan 2004 05:40:18 GMT, Jere Lull wrote:

In article ,
(Steven Shelikoff) wrote:

On Fri, 09 Jan 2004 07:51:04 GMT, Jere Lull wrote:

In article ,
Rick wrote:

The element cannot possibly know what mechanism is used to
establish fluid flow through the filter. The only thing the
filter sees is rate of flow and as it clogs, differential.
Anyone who claims otherwise is ignoring some other factor or
talking BS.

ONLY if you're only looking at the filter.

We are only looking at the filter, not taking into account the casing,
plumbing, etc.

Steve

I believe that the case is a pretty major component to ignore in a
polishing system. A case designed for partial vacuum may not properly
handle whatever pressure the pump can deliver. If the company says "only
suction", I suspect it wasn't designed for pressure.

When looking at the entire fuel polishing system, we're not ignoring the
case. When looking strictly at the difference in the performance of the
filter media, by definition we are ignoring the case. My question is
why does it matter strictly to the performance of the filter media
whether fuel is being pushed through by a pump or pushed through by
atmospheric pressure?

Getting back to the filter alone: Since I believe most pumps can "push"
better than they can "pull", we should also consider the maximum
differential the filter can handle before it tears or otherwise breaks
down. Rich mentioned a design limit of 6" vacuum (about 3 psi?) What can
these pumps deliver?

Typical of the pumps used in this application is the Walbro 6802. I
don't see the spec on vacuum for it on the web but it delivers 7 psi
pressure so the vacuum is probably somewhat less. I do have the manual
on the boat, but I'm not going down there anytime soom. In application,
I haven't measured more than about 5 psi of vacuum before I changed
elements. The Racors have no problem with 7 psi vacuum or pressure.

Steve

Steven Shelikoff wrote:


...filter media, by definition we are ignoring the case. My question is
why does it matter strictly to the performance of the filter media
whether fuel is being pushed through by a pump or pushed through by
atmospheric pressure?

It's often a function of system and pump design. For e.g., when
using a centrifugal pump (or liquid ring, and sometimes vane), the
inlet is typically sized larger than the outlet. The result is
higher fluid velocity on the outlet side versus the 'suction'
side. Higher velocity, higher impact pressure, often resulting in
better particulate retention.

Additionally, all pump curves I've seen are, to some degree, more
dependent on suction head than discharge head, and cavitation
becomes an issue (i.e. efficiency drops more rapidly for loss of
head on the suction side than for increase in head on the
discharge side). Thus, when the filter begins to clog, you not
only lose flowrate due to loop pressure drop increasing, you lose
pump *efficiency* as well, exacerbating the problem. The result
is, typically, less allowable filter loading before the system
performance is affected, so more frequent filter changes.

Whether this is an issue with the Racors or not, I have no idea,
not being familiar with them. But if you want maximum system
efficiency, maximum filter loading capacity, and longest interval
between changeouts, discharge filtration is the way to go.

Or...just use more *wind*, and all this diesel stuff is moot :-)

Keith Hughes

Steven Shelikoff wrote:


...filter media, by definition we are ignoring the case. My question is
why does it matter strictly to the performance of the filter media
whether fuel is being pushed through by a pump or pushed through by
atmospheric pressure?

It's often a function of system and pump design. For e.g., when
using a centrifugal pump (or liquid ring, and sometimes vane), the
inlet is typically sized larger than the outlet. The result is
higher fluid velocity on the outlet side versus the 'suction'
side. Higher velocity, higher impact pressure, often resulting in
better particulate retention.

Additionally, all pump curves I've seen are, to some degree, more
dependent on suction head than discharge head, and cavitation
becomes an issue (i.e. efficiency drops more rapidly for loss of
head on the suction side than for increase in head on the
discharge side). Thus, when the filter begins to clog, you not
only lose flowrate due to loop pressure drop increasing, you lose
pump *efficiency* as well, exacerbating the problem. The result
is, typically, less allowable filter loading before the system
performance is affected, so more frequent filter changes.

Whether this is an issue with the Racors or not, I have no idea,
not being familiar with them. But if you want maximum system
efficiency, maximum filter loading capacity, and longest interval
between changeouts, discharge filtration is the way to go.

Or...just use more *wind*, and all this diesel stuff is moot :-)

Keith Hughes

Well since you dont seem to know that a centrifuge is typically used
for ABOVE 10% solids removal and polishing filtration is typically used
for 0.05% solids removal .... then I guess that I WONT trust you.

In article t, Rick
wrote:

Rich Hampel wrote:

There is a valid doctoral discertation awating the person who solves
this dilemma ...

It is not a dilemma that keeps many boaters awake at night,
trust me.

Rick

Well since you dont seem to know that a centrifuge is typically used
for ABOVE 10% solids removal and polishing filtration is typically used
for 0.05% solids removal .... then I guess that I WONT trust you.

In article t, Rick
wrote:

Rich Hampel wrote:

There is a valid doctoral discertation awating the person who solves
this dilemma ...

It is not a dilemma that keeps many boaters awake at night,
trust me.

Rick

Ask the centrifuge manufacturer whats the reduction efficiency (per
minute) vs. a dead end filter at 98-100% efficiency.
On a per gram basis what is the cost (including initial capital cost)
be tween filtration and centrifugation?
Ask the centrifuge manufacturer how long the electric cord needs to be
when you're out at sea.
Ask what the rebuild charge is for the disks when they become
misaligned or wear out.... ditto seals.
Ask when do you shut down the centifuge when you know that the particle
distribution is what you want to obtain .... with out accessory
instrumentation and the knowledge of it proper usage. Do you have ANY
idea?

Now Mr. Know it ALL - go to the Alpha Laval site and look at the
recommendations carefully .... and see the differences listed there for
the selection criteria between filtration and centrifugation ..... wow!
whaddaya know the centrifuge recommendationis for 10% solids and above.


Tell me this ONE answer..... how long do you have to centrifuge fuel
oil to get to 2uM particle levels? If you cant answer this, then you
have NO idea of the purpose of a centrifuge, the reduction possible,
nor the applicability.



In article t, Rick
wrote:

Rich Hampel wrote:

The use of a centrifuge on the small volume boat tankage .... borders
on ludicrous.

your opinion is not universal. Besides, we were writing
about FUEL POLISHING ... an activity normally performed
alongside a dock at rather extended intervals.

Centrifuges are extreme high maintenance rotating and
power consuming equipment

Just because you don't like them ... and you have a peculiar
vision of "extreme" maintenance.

and do NOT effect total removal/separation of
emulsions. If you have enough power to run a centrifuge, then I
suggest that you rip out the fossil fuel engine and simply replace with
an electric motor for propulsion.

A rather extremist position. There are plenty of boats under
75 feet that use a centrifuge to handle fuel separation
tasks. Why do you think Alfa Laval build one the size of a
gallon milk jug? Your personal view and experience does not
define the marine industry in the 21st century.

Do you also use a nephalometer to
arrive at when the centrifugation is complete?

Once through will do.

As an aside .... a water emulsion will enhance the combustion
efficiency by increase of the apparent cetane number of the fuel, or
the octane number in a gasoline engine.

Water does not increase the cetane number ... do you know
what that means anyway?

Water serves to reduce the temperature of combustion and
thereby reduce the formation of oxides of nitrogen in a diesel.

Its the FREE water thats the
'problem' as simply 'slugs' of free water simply do not burn.

Got that one wrong too. There are several techniques
available in large diesels that layer the fuel and water
injected, and another that injects water first then fuel.

Let's stick to filtration and fuel polishing. If you want to
have a snit go chat with K over on rec. boats.

Rick

Ask the centrifuge manufacturer whats the reduction efficiency (per
minute) vs. a dead end filter at 98-100% efficiency.
On a per gram basis what is the cost (including initial capital cost)
be tween filtration and centrifugation?
Ask the centrifuge manufacturer how long the electric cord needs to be
when you're out at sea.
Ask what the rebuild charge is for the disks when they become
misaligned or wear out.... ditto seals.
Ask when do you shut down the centifuge when you know that the particle
distribution is what you want to obtain .... with out accessory
instrumentation and the knowledge of it proper usage. Do you have ANY
idea?

Now Mr. Know it ALL - go to the Alpha Laval site and look at the
recommendations carefully .... and see the differences listed there for
the selection criteria between filtration and centrifugation ..... wow!
whaddaya know the centrifuge recommendationis for 10% solids and above.


Tell me this ONE answer..... how long do you have to centrifuge fuel
oil to get to 2uM particle levels? If you cant answer this, then you
have NO idea of the purpose of a centrifuge, the reduction possible,
nor the applicability.



In article t, Rick
wrote:

Rich Hampel wrote:

The use of a centrifuge on the small volume boat tankage .... borders
on ludicrous.

your opinion is not universal. Besides, we were writing
about FUEL POLISHING ... an activity normally performed
alongside a dock at rather extended intervals.

Centrifuges are extreme high maintenance rotating and
power consuming equipment

Just because you don't like them ... and you have a peculiar
vision of "extreme" maintenance.

and do NOT effect total removal/separation of
emulsions. If you have enough power to run a centrifuge, then I
suggest that you rip out the fossil fuel engine and simply replace with
an electric motor for propulsion.

A rather extremist position. There are plenty of boats under
75 feet that use a centrifuge to handle fuel separation
tasks. Why do you think Alfa Laval build one the size of a
gallon milk jug? Your personal view and experience does not
define the marine industry in the 21st century.

Do you also use a nephalometer to
arrive at when the centrifugation is complete?

Once through will do.

As an aside .... a water emulsion will enhance the combustion
efficiency by increase of the apparent cetane number of the fuel, or
the octane number in a gasoline engine.

Water does not increase the cetane number ... do you know
what that means anyway?

Water serves to reduce the temperature of combustion and
thereby reduce the formation of oxides of nitrogen in a diesel.

Its the FREE water thats the
'problem' as simply 'slugs' of free water simply do not burn.

Got that one wrong too. There are several techniques
available in large diesels that layer the fuel and water
injected, and another that injects water first then fuel.

Let's stick to filtration and fuel polishing. If you want to
have a snit go chat with K over on rec. boats.

Rick

Rich Hampel wrote, all offended and whiny:

Ask the centrifuge manufacturer whats the reduction efficiency (per
minute) vs. a dead end filter at 98-100% efficiency.
On a per gram basis what is the cost (including initial capital cost)
be tween filtration and centrifugation?
Ask the centrifuge manufacturer how long the electric cord needs to be
when you're out at sea.
Ask what the rebuild charge is for the disks when they become
misaligned or wear out.... ditto seals.
Ask when do you shut down the centifuge when you know that the particle
distribution is what you want to obtain .... with out accessory
instrumentation and the knowledge of it proper usage. Do you have ANY
idea?

Yeah, I use them all the time. They work very well.

Now Mr. Know it ALL - go to the Alpha Laval site and look at the
recommendations carefully .... and see the differences listed there for
the selection criteria between filtration and centrifugation ..... wow!
whaddaya know the centrifuge recommendationis for 10% solids and above.

Tell me this ONE answer..... how long do you have to centrifuge fuel
oil to get to 2uM particle levels? If you cant answer this, then you
have NO idea of the purpose of a centrifuge, the reduction possible,
nor the applicability.

I take it you don't like centrifuges. It also sounds like
you have never seen or used one.

Methinks you protest too much ... what is your problem anyway?

Rick