Boat talk is a web page we are putting together at Blue Collar Sportfishing in an effort to disseminate information in areas of our expertise about boat repairs improvement and modification as well as the great sport of fishing. The information contained in this page are the opinion of the owner and are based on sound engineering principles and years on experience. The implementation of this information is strictly at the risk of the reader.
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Do you have the proper safety factor for your engine shafts or why has my shaft parted again?
by Captain Jim Mahoney
Reservations: (215) 990-1938
or (215) 990-1284
Quick Tip from Blue Collar Man
Fuel Filtratrion Sizing
Selecting the right size or flow rating for a filter housing is as important as the filtration capacity of the filter, which is typically termed in Microns (one Micron is equal to 1/1000 of a millimeter) Following the KISS (Keep It Simple Stupid) principle of engineering, the lower the Micron rating the finer the filtration i.e. a one (1) Micron filter has better or finer filtering capabilities than a thirty (30) Micron filter, hence the filter rating is inversely proportional to its effectiveness meaning the lower the numerical value the higher the filtration or Low Number = Greater Filtration.
All filter housings have a flow rating termed in GPH (gallons per hour) or GPM (gallons per minute). Sizing is important, if too small and you will restrict fuel flow to your power plant starving the combustion process. Too large and you will be wasting resources, i.e. more expensive filter cartridges, larger physical size and over all greater initial capital investment.
Here are some handy Blue Collar Man rules of thumb for selection of your filter housing. Keeping in mind the KISS principle as none of us are as smart as we think we are. A typical four (4) cycle diesel engine returns 2 to 4 time as much fuel as it burns and two (2) cycle diesel engines return 5 to 6 times. Thus to calculate the flow through a injection pump we would multiply peak engine fuel consumptions by 3.5 or 4 then divide by 60 to obtain the gallon per minute flow rate of fuel feeding a typical 4 cycle diesel engine and hence the fuel through put of the filter. The second and simpler rule of thumb is simply brake horsepower X 0.18 = gallons per minute feeding the fuel injection pump.
Practical Example: Cummins 6CTA rated @ 430 BHP burns 24.2 Gal/HR at WOT (wide open throttle)
•WOT rule of thumb
WOT rule of thumb24.2 Gal/Hr x 3.5 = 84.7 GPH
84.7 GPH / 60 Min per Hour = 1.41 GPM
•Percentage rule of thumb
Percentage rule of thumb430 BHP x 0.18 = 77.4 GPH
77.4 GPH / 60 Min per Hour = 1.29 GPM
•Available Racor Models:
Available Racor Models: 500FH rated 60 GPH
900FH rated 90GPH
1000FH rated 180 GPH
For this installation a Racor 900FH housing would be a smart selection as this housing is rated at 90 GPH.
Racor is an industry standard for diesel fuel filter housings, there are many other selection available but Racor was used as a representative example.
