Drum Vent Desiccant
Written by Rickdatech
Biodiesel will absorb some water from the air over time. If you live in a humid area, water will encroach into your fuel dispensing drum and spoil all that hard work you put into getting it super dry. However if you put a desiccant vent on your drum, you can actually make your biodiesel even drier.
Air moves in and out of the drum on a daily cycle as the drum is heated in the daytime, It expels air and draws in air at night when it cools. Air also moves in and out of the drum when we add biodiesel to or pump biodiesel from the drum. All this air gets forced through our desiccating vent, drying the air in the drum and keeping water from contaminating our biodiesel.
Desiccating vents all work the same way. They filter the air through silicon gel to soak up all the water vapor. You can buy them for a pretty penny or you can make one for yourself out of pvc pipe and silicon gel. Silicon gel is available at most hobby stores as a crystal used to dry flowers. Make sure you get the kind that has "indicating crystals". These indicating crystals change color from blue to pink as it gets saturated with water.
The crystals may be expensive to purchase, but they can be used indefinitely as long as you don't soak them in biodiesel. When they turn pink they can be reclaimed by heating. Different silica gels have different temperatures to regenerate. Typical blue-pink gels regenerate after several hours at 200F.
One note of importance is that you don't want to force heated air through the silica gel because they don't absorb water very well when heated. Ambient temperature is best.
How a Drum Desiccant Breather works - AGM Containers
Desiccators: Theory & Characteristics - AGM Containers
Desiccant Breather - amazon.com products
Proper Headspace Management Starts with the Right Breather Option - Machinery Lubrication