Water Blocking Filters
Written by Rickdatech
Water blocking fuel filters are both popular among homebrewers and commonly misused. They are typically 10 micron spin on filters like this goldenrod waterblock filter and are capable of capturing free and emulsified water, but not dissolved water. They have some water absorbing material, typically cotton, wrapped around the fitler. As the filter absorbs water, the water absorbing material will swell, blocking the flow. Eventually, once it has reached its limit of water, it will go into bypass mode. The filter is spring loaded and when it is fully clogged, the resulting backpressure will overcome the spring pushing the filter out of the way so fuel can go around the clogged filter. It only takes a few tablespoons of water to clog one of these filters.
The best way to use one of these filters is as insurance on clean dry oil. that way if for some reason a few drops of water makes it into your finished biodiesel tank the water block filter can catch it before it goes into your vehicle.
Goldenrod Water Block Filters at Amazon.com