It’s the rare marine industry professional who hasn’t encountered a clogged primary diesel fuel filter, or had a customer who has dealt with one. It’s a fact of life if you work around diesel engines. However, if you show some care and forethought when selecting a filter, you might make such events more of an inconvenience than an emergency for your customers.
More is Better
When it comes to filtration, there’s no such thing as too much. I’m often taken to task by boatbuilders for suggesting to buyers that a larger primary filter be installed. “It’s overkill and a waste of money,” they exclaim. But larger filters are capable of capturing and safely holding more water and debris. Equally as important, larger filters, like the Racor MA Turbine series, are infinitely easier to inspect and service. Small, spin-on or sandwich-type filters may be technically correct for a given engine or genset, but they’re cumbersome and messy to replace and inspect, especially in a seaway. They are also more prone to air ingestion, they retain fewer contaminants, and their replacement elements are often more difficult to obtain. All of these obstacles make it less likely that a boat owner will be willing or able to tackle this sort of challenge. Furthermore, and unlike larger Turbine series filters, in order for them to meet the Underwriters Laboratory (UL) Marine or American Boat & Yacht Council (ABYC) requirements for flame resistance, these smaller filters cannot include a clear plastic bowl; it must instead be metal, which means it can’t be monitored for water or accumulation of debris.
In addition, larger filters like the Turbine MA series feature extremely valuable yet often overlooked traits that include a large, clear bowl, a T handle that makes for easy, tool-free replacement, provisions for a water-in-fuel indicator, full UL Marine compliance for fire resistance, O-ring fittings that are virtually guaranteed to be leak free, and readily available replacement elements in the appropriate primary ratings of 10 and 30 microns.
Far too few primary fuel filter installations take advantage of a small, relatively inexpensive yet invaluable piece of gear, a vacuum gauge. Without the gauge, you have no way of knowing how much contamination has accumulated within the filter, and therefore no accurate means of knowing when it should be replaced. If a filter element shows no vacuum restriction, there’s no need to replace it. A vacuum gauge also serves as a useful troubleshooting tool.
It’s worth noting that not all primary fuel filters meet UL Marine fire-resistance requirements; often these noncompliant filters are installed by boatbuilders and installers who don’t realize their lack of compliance. In order to comply with this standard, filters and other fuel-carrying components must be capable of withstanding two and a half minutes of exposure to flame without failing or leaking. Filters with plastic bowls and no heat shield nearly always lack compliance. Compliant Racor Turbine MA series and others like them incorporate two critical features: a heat shield for the bowl, and a metallic rather than plastic drain plug, which would melt when exposed to flame. Tellingly, the label on the Racor Turbine MA filters is blue; while Racor Turbine filters that lack flame resistance utilize labels with red or black lettering. Fortunately, noncompliant filters that lack heat shields and metallic drain plugs can be retrofitted with these parts for a fraction of the price of a complete new, compliant filter assembly.
While many primary filters include provisions for drain valves, few include them out of the box. They must be added. When doing so, be sure to select, once again, only valves that meet UL Marine and/or ABYC standards (compliant valves will be marked “UL Marine”). These are characterized by a lack of springs to retain tension and fuel tight integrity, rotation that is no more and no less than 90°, and of course flame resistance, making plastic valves unacceptable. An added advantage of the metallic valves is they are less restrictive, and thus are less prone to clogging. If they should clog, their straight-through design enables them to be easily cleared with a small screwdriver or similar narrow object. Finally, valve drains should be capped or plugged to prevent a fuel spill should the valve handle be inadvertently moved.
About the Author: For many years a full-service yard manager, Steve now works with boat builders and owners and others in the industry as Steve D’Antonio Marine Consulting. He is an ABYC-certified Master Technician, and sits on that organization’s Hull and Piping Project Technical Committee. He’s also the technical editor of Professional BoatBuilder.