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#11
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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 |
#12
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Fuel Polishing again.
Good point. I hadn't thought of that. But then I am not using Raycor
fuel/water separators for the polishing system. I am using depth filters rather than surface filters so the water should be trapped within the filters. Also, I do have Raycor on the engine system so any residual water will be handled there as well. Doug s/v Callista "Rick" wrote in message hlink.net... 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 |
#13
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Fuel Polishing again.
Good point. I hadn't thought of that. But then I am not using Raycor
fuel/water separators for the polishing system. I am using depth filters rather than surface filters so the water should be trapped within the filters. Also, I do have Raycor on the engine system so any residual water will be handled there as well. Doug s/v Callista "Rick" wrote in message hlink.net... 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 |
#14
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Fuel Polishing again.
NOPE!
In pressure mode, the filter will also act as a 'coalescer' (bringing similar surface tension fluids together to make larger and larger sized particles) and such particles will settle out into a 'drop-out-pot' ...... or usually into the bottom of the filter bowl (bowl pointing downwards). The smaller the retention size of the filter media the more efficient the coalescing efficiency. On the very bottom of the filter bowl, add a pigtail of oil compatible transluscent plastic tube (Tygon, etc.) with a cock on the end .... when you see water in the pigtail simply drain the bowl. Thats the same way a racor with an integral clear plastic knock-out-pot works. If you are regularly polishing the fuel the coalesced emulsions will be removed/trapped in the inverted filter bowl .... that why you put the dip tube for the recirc system at the VERY bottom of the tank and a drain cock on the inverted filter bowl. Dont want air leaks or fuel oil leaks ------ dont use compression fittings, use flared or better fittings. Pump should have a SCREEN (preferably integral) for protection to prevent damage by *huge* particles that would tear the rubber impeller or wobble plate. I say again, if you want long service life and efficient filtration employ PRESSURE filtration, especially on a recirculation system. The ONLY reason I can think of why fuel systems in boats use vacuum filtration is ........... the engine manufactures supply the lift pump and 'guard' filter - and puts it on the engine ...... and not on the tank (where it SHOULD BE). Cheap and dirty solution, easier for the boat builder - less wiring, less design, less effort, .... In article k.net, Rick wrote: 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 |
#15
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Fuel Polishing again.
NOPE!
In pressure mode, the filter will also act as a 'coalescer' (bringing similar surface tension fluids together to make larger and larger sized particles) and such particles will settle out into a 'drop-out-pot' ...... or usually into the bottom of the filter bowl (bowl pointing downwards). The smaller the retention size of the filter media the more efficient the coalescing efficiency. On the very bottom of the filter bowl, add a pigtail of oil compatible transluscent plastic tube (Tygon, etc.) with a cock on the end .... when you see water in the pigtail simply drain the bowl. Thats the same way a racor with an integral clear plastic knock-out-pot works. If you are regularly polishing the fuel the coalesced emulsions will be removed/trapped in the inverted filter bowl .... that why you put the dip tube for the recirc system at the VERY bottom of the tank and a drain cock on the inverted filter bowl. Dont want air leaks or fuel oil leaks ------ dont use compression fittings, use flared or better fittings. Pump should have a SCREEN (preferably integral) for protection to prevent damage by *huge* particles that would tear the rubber impeller or wobble plate. I say again, if you want long service life and efficient filtration employ PRESSURE filtration, especially on a recirculation system. The ONLY reason I can think of why fuel systems in boats use vacuum filtration is ........... the engine manufactures supply the lift pump and 'guard' filter - and puts it on the engine ...... and not on the tank (where it SHOULD BE). Cheap and dirty solution, easier for the boat builder - less wiring, less design, less effort, .... In article k.net, Rick wrote: 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 |
#16
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Fuel Polishing again.
On Thu, 08 Jan 2004 02:51:46 GMT, Rich Hampel
wrote: NOPE! In pressure mode, the filter will also act as a 'coalescer' (bringing similar surface tension fluids together to make larger and larger sized particles) and such particles will settle out into a 'drop-out-pot' ..... or usually into the bottom of the filter bowl (bowl pointing downwards). The smaller the retention size of the filter media the more efficient the coalescing efficiency. On the very bottom of the filter bowl, add a pigtail of oil compatible transluscent plastic tube (Tygon, etc.) with a cock on the end .... when you see water in the pigtail simply drain the bowl. Thats the same way a racor with an integral clear plastic knock-out-pot works. If you are regularly polishing the fuel the coalesced emulsions will be removed/trapped in the inverted filter bowl .... that why you put the dip tube for the recirc system at the VERY bottom of the tank and a drain cock on the inverted filter bowl. Dont want air leaks or fuel oil leaks ------ dont use compression fittings, use flared or better fittings. Pump should have a SCREEN (preferably integral) for protection to prevent damage by *huge* particles that would tear the rubber impeller or wobble plate. I say again, if you want long service life and efficient filtration employ PRESSURE filtration, especially on a recirculation system. The ONLY reason I can think of why fuel systems in boats use vacuum filtration is ........... the engine manufactures supply the lift pump and 'guard' filter - and puts it on the engine ...... and not on the tank (where it SHOULD BE). Cheap and dirty solution, easier for the boat builder - less wiring, less design, less effort, .... All this begs the question, why does the filter media care whether it's in "pressure" mode or "vacuum" mode? Sure, the plumbing and filter cases care. But the media only sees a pressure differential across it. What's the difference to the media if the there is 14psi (atmospheric pressure) on one side and, say, 10 psi (a 4 psi vacuum drawing fuel across the media) on the other side vs. 18 psi (4 psi pressure pushing fuel across the media) on one side and 14 psi (atmospheric) on the other? IOW, even if the pump is past the filter drawing fuel through it, the filter is still in "pressure" mode because it's really the atmospheric pressure pushing fuel through the filter. Steve |
#17
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Fuel Polishing again.
On Thu, 08 Jan 2004 02:51:46 GMT, Rich Hampel
wrote: NOPE! In pressure mode, the filter will also act as a 'coalescer' (bringing similar surface tension fluids together to make larger and larger sized particles) and such particles will settle out into a 'drop-out-pot' ..... or usually into the bottom of the filter bowl (bowl pointing downwards). The smaller the retention size of the filter media the more efficient the coalescing efficiency. On the very bottom of the filter bowl, add a pigtail of oil compatible transluscent plastic tube (Tygon, etc.) with a cock on the end .... when you see water in the pigtail simply drain the bowl. Thats the same way a racor with an integral clear plastic knock-out-pot works. If you are regularly polishing the fuel the coalesced emulsions will be removed/trapped in the inverted filter bowl .... that why you put the dip tube for the recirc system at the VERY bottom of the tank and a drain cock on the inverted filter bowl. Dont want air leaks or fuel oil leaks ------ dont use compression fittings, use flared or better fittings. Pump should have a SCREEN (preferably integral) for protection to prevent damage by *huge* particles that would tear the rubber impeller or wobble plate. I say again, if you want long service life and efficient filtration employ PRESSURE filtration, especially on a recirculation system. The ONLY reason I can think of why fuel systems in boats use vacuum filtration is ........... the engine manufactures supply the lift pump and 'guard' filter - and puts it on the engine ...... and not on the tank (where it SHOULD BE). Cheap and dirty solution, easier for the boat builder - less wiring, less design, less effort, .... All this begs the question, why does the filter media care whether it's in "pressure" mode or "vacuum" mode? Sure, the plumbing and filter cases care. But the media only sees a pressure differential across it. What's the difference to the media if the there is 14psi (atmospheric pressure) on one side and, say, 10 psi (a 4 psi vacuum drawing fuel across the media) on the other side vs. 18 psi (4 psi pressure pushing fuel across the media) on one side and 14 psi (atmospheric) on the other? IOW, even if the pump is past the filter drawing fuel through it, the filter is still in "pressure" mode because it's really the atmospheric pressure pushing fuel through the filter. Steve |
#18
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Fuel Polishing again.
Steven Shelikoff wrote:
IOW, even if the pump is past the filter drawing fuel through it, the filter is still in "pressure" mode because it's really the atmospheric pressure pushing fuel through the filter. The difference is that if the pump suction pulls water and fuel directly from the tank it will do an excellent job of mixing it up to form an emulsion that will not filter out very effectively. The path should be, a basket strainer to catch the chunks, a separarator/filter to eliminate the bulk of the water and the smaller suspended particles, the pump, then the finer stages of filtration. This is all assuming you don't have access to a centrifuge which is really the best way to handle the process. Rick |
#19
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Fuel Polishing again.
Steven Shelikoff wrote:
IOW, even if the pump is past the filter drawing fuel through it, the filter is still in "pressure" mode because it's really the atmospheric pressure pushing fuel through the filter. The difference is that if the pump suction pulls water and fuel directly from the tank it will do an excellent job of mixing it up to form an emulsion that will not filter out very effectively. The path should be, a basket strainer to catch the chunks, a separarator/filter to eliminate the bulk of the water and the smaller suspended particles, the pump, then the finer stages of filtration. This is all assuming you don't have access to a centrifuge which is really the best way to handle the process. Rick |
#20
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Fuel Polishing again.
Pull the fuel through the filter, don't push.
"Doug Dotson" wrote in message ... 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 |
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