Features September 2018 Issue

Reviving Fuel Filter Beads — Again and Again

A few years back, we introduced fuel tank vent filters as a simple step toward drier fuel (see Practical Sailor January 2013, EPA Mandate Sparks Fuel-vent Filter Test and PS January 2014 Diesel Tank Vent Filters). The caveat was that eventually the resin would need regeneration.

fuel filter beads melted
Pink silica beads gradually turn to blue as they are warmed over a gas grill.

We wished they could be as maintenance free as the carbon canister on your car, but they lack the regeneration cycles programmed into your car. The makers say the silica gel resin should be replaced annually, but Practical Sailor testers have found that three years is about right for diesel and five years for E-10 gasoline.

At that point the gel turns from blue to pink as it becomes saturated with water and regeneration with heat is needed. Note that some pink in the filter is fine; it is only when it becomes nearly all pink that it is spent.

The rejuvenating process is as simple as dumping the resin in a pan and heating over a low flame while stirring periodically. To avoid overheating the resin, the flame should regulated such that the process takes about 20-30 minutes.

Although we regenerated the resin for this gasoline vent filter on grill, other testers actually used galley stoves and reported no noticeable odor in the cabin. Practical Sailor recommends the outdoor grill, just to be safe.

If your filter material is wet or contaminated with fuel, you should revise your installation, either by moving it to a higher location, or adding a cover to prevent water ingress. These beads can be rinsed, dried and reused. After heating, let cool and you are good for another three to five years.

Comments (4)

True enough re. cobalt chloride. But that is what fuel driers are filled with. It has proven more durable in hydrocarbon applications.

Silica gel-based driers intended for galley use should be the orange/green type, but we've seen exceptions, so this is a good warning.

Posted by: Drew Frye | September 6, 2018 7:17 PM    Report this comment

If your silica gel turns blue, then it is using Cobalt Chloride as the indicator which is pretty toxic. So, it might be best not to use a pot from the galley to dry it. Alternatively, there is a non-toxic silica gel that turns from orange to green as it becomes saturated with water. This may be more important if you leave desiccant driers in cupboards and drawers around the boat where they can release dust as the beads rub against each other. We bought a gallon of orange and use it for everything.

Posted by: Darren Bos | August 28, 2018 10:43 AM    Report this comment

It is probably simpler to replace them, but they can still be regenerated.

Spread them on a rag and sponge of the excess fuel as well as possible. Leave them in a spread out in a humid place until they fully change color. This may take several weeks. Do NOT use liquid water; this will cause the beads to shatter. The water in the air will gradually displace the fuel, because it is more strongly adsorbed than fuel. Then regenerate as usual.

Prevention is best. Install the drier in a high loop. Additional protection can be provided by anti-surge valves from Raycor (Lifeguard) or Atwood. These are required by code for installation of carbon vent filters in new gasoline powered boats.

Posted by: Drew Frye | August 27, 2018 9:06 AM    Report this comment

is it reasonable to assume that the beads should be replaced if fuel contaminated and not attempt to regenerate?

Posted by: my1972ih | August 25, 2018 2:29 PM    Report this comment

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