FYI and not stirring the pot!
The reason that the primary filter (vacuum side) on a class eight truck or on any vacuum feed setup is always low or most always low is because air, entrained or free, will not pass through the fillter under a low pressure differential. About 10/15 inches h2O (not hg. mercury). The reason the filters on the pressure side of the transfer pump are always full is because the pressures exceed the 10/15 in. h2O psi and air will pass through most any filter at pressures exceeding this. This equates to about 35/40 PSI in most filters. Because of all of this, any system trying to separate air at these pressures or higher will pretty much fail. The Fuel Preporator, AirDog systems all operate at output pressures below this level.
The FP AirDog system has a primary (positive) air separation system that removes the air separated by the filter media from the filter at this point and vents it into the return line after the regulator. Any air that may be in the interior of the filter element, and the fuel, has two places to exit the filter. One is out to the engine through the pickup tube extending down into the filter and two is back to the fuel tank through the passageway between the nipple and pickup tube. If the flow rate of the fuel is low enough, the air will float up and out with the fuel returning to the tank. If the flow rate is to great for the air to float, it will go with the fuel to where ever the fuel goes, to the engine (not good) and to the tank if the regulator is open enough to allow fuel to flow back to the tank. Because the FP AirDog has the positive air separation feature (the fass does not) it will separate the air (to protect your engine) regardless of the regulator position. Additionally, the original Fuel Preporator as good as it was, using the 5" od, filter would not separate air from fuel above 150 gph. A flow velocity above 150gph could trap the air in the filter (it could not float up against the incoming flow to exit). Therefore, it could not be made smaller or flowhigher flows. The answer to this problem was the addition of the (patented) 'flow dividers'. The flow dividers separate the area between the filter nutplate and filter head into an inlet side and an outlet side. Now, the air is swept unrestricted over and up to the primary gas exit port. With these features the small and compact AirDog, with 3" OD filters, separates air from fuel at over 150 gph. And, the larger class 8 truck model Fuel Preporator, slightly smaller than the fass and using filters the same diameter as the fass, could separate air from fuel at up to 310 GPH. By the way, the Fleetguard FS-1023 water separator seen on many fass units is listed as the crossover product to the Fuel Preporator water separator made by Fleetguard.
Regardless of what one may think, unless the (patented) primary gas exit port and flow dividers of the Fuel Preporator are in the system, air will only be separated from the fuel at a very low flow rate and definitely not at high pressures (pressures above 40psi). If you think it will, you are just fooling your self!
To quote Brad Ekstam from a letter he sent to "Diesel Owner/Operator": "When discussing the benefits of the Fuel Preporator and the sound physics behind this product, many of you wanted to purchase and put the Fuel Preporator to use immediately in your business."
Answer this, why would you want to use a product that does not include all of, as Brad stated "the sound physics behind the product"? To again quote Brad when asked: "the Fuel Preporator without the air bleed port would operate in the same way as the FASS..." he responded "I am saying you would be taking air out the same way we do."
"Included in the letter to "Diesel Owner/Operator" was an Article, "TEST CELL PERFORMANCE" which started: "The FASS Fuel System was designed to give yesterday's and todays diesel engine "Test Cell Performance in Real World Conditiions." The original writing, Copyrighted and registered, started: "The Fuel Preporator was designed..."
I hope this will clear a little of the air on this subject! If not, there are volumes of examples like this that are fact and verifiable.
Thanks for your time!
Charlie
op: Oh and FASS rules :rockwoot: