Desiccant/Hygroscopic Breather Vent for Fuel Storage

[Zed254]

I've just changed out the fuel in my 50 gallon storage tank and began thinking of installing a desiccant breather. The ones I found were expensive and throw-away units. I wanted something I could recharge with desiccant pellets bought online. This is what I came up with:

1) I started with a Goldenrod fuel filter. I bought the cheapest one available and it was tapped for 1" pipe. They have a version tapped for 3/4" pipe.
2) My original plan was to drop a 1/4" fuel hose into the bowl of the filter - filled with desiccant - and use the 'IN' and 'OUT' tapped 1" pipe fittings. The problem with this approach is the center filter thread for the Goldenrod filter is a bolt thread: 1 1/8 - 12 NF-2A. The few tube/pipe fitting adapters I could find in this thread were quite expensive.
3) New plan: plug the 1" pipe 'IN' port and allow air to enter the desiccant vent through the pellets from the bowl's fuel drain. I attached the 'OUT' port of the desiccant vent to the fuel storage tank using 1/4" fuel line. I had already installed a roll-over vent in the fuel tank and it had a 5/16" hose barb on it.
4) I used a blue Scotch-Brite scrubbing pad (cut to fit) for a bottom of bowl filter and rolled up some Scotch-Brite and stuffed it in the 1 1/8 - 12NF threaded hole to filter that end of my vent.
5) There are no mounting holes for the Goldenrod fuel filter so I mounted the desiccant vent to the hold down straps for my fuel tank using a 4-1/2" hose strap covered in 3/8" braided nylon wire sleeving, a piece of thin chain, and a screwed chain link.
6) I expect it to work.....but only time will tell.

 

[nextalcupfan]

I've been thinking about an in-line desicant dryer for air lines.

Amazon.com: Le Lematec Desiccant Air Compressor Filter with Teflon, Water Separator, Air Compressor Dryer ZN312-D-C1: Automotive

Buy Le Lematec Desiccant Air Compressor Filter with Teflon, Water Separator, Air Compressor Dryer ZN312-D-C1: Air Dryers - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

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[Light in the Dark]

Not sure how it would fare long term with the fumes, but its definitely cheap enough to work something out. Vacuum will find a way to pull no matter the medium.... there could definitely be something to this. Im just about to refill my drums for the winter and I need to find a different solution myself.

 

[nextalcupfan]

I'd be worried about gasoline fumes, but are diesel fumes that caustic?
It can handle oil, the beads are replaceable, and the body is zinc.
I don't see what could go wrong. (Famous last words I know)

 

[Light in the Dark]

I thought it was plastic, I didn't read the fine details. Even better.

The flow is directional though, so you might need to run (2) off a T so one can relieve negative pressure, the other positive pressure (one mounted inverted).

 

[Zed254]

We used to put desiccant vents on our extruder gearboxes. Nice throw away units that cost WAY more than I want to pay. They hand screwed into a pipe thread on top of the gearbox. Air flow was bi-directional into and out of the gearbox. When extruding material the gearbox would get warm and air would expand out through the desiccant beads. After a campaign the machine would be off and cool to ambient temperature. As the air in the gearbox cooled air would flow back through the desiccant beads into the gearbox.

I'm thinking the air flow through the desiccant vent will be very minor unless I am pulling fuel out of the tank during operation. My last fuel was in the tank for 2 + years because our outages are usually less than 15 hours in Virginia Beach. This fuel is for the long one when a hurricane really messes the area up and I empty my Jerry cans.

Materials of construction are good for gas and diesel....except my added Scotch-Brite 'filters' and they are a nylon like polymer. The Goldenrod fuel filter has a Zinc top with plastic bowl.

I'll need to monitor the desiccant for any diesel fume caused deterioration.

 

[nextalcupfan]

I thought it was plastic, I didn't read the fine details. Even better.

The flow is directional though, so you might need to run (2) off a T so one can relieve negative pressure, the other positive pressure (one mounted inverted).

I'm sure air will pass both ways, it probably just has a screen filter on one side so thats the side they want the air inlet on.

Also all we really care about is the air going into the tank being free of moisture, so if I installed one it would be with the inlet side facing away from the tank (exposed to the air) and the outlet going towards the tank.

 

[reset2]

Great idea. Never even thought about desiccant drying the air. Now to improve on your idea. With the concern of contamination with the fuel "off gassing" how about two check valves. Air in thru one check thru the desiccant filter, air out thru other check to atomsphere not filtered.

Sent from my SM-G935V using Tapatalk

 

[Zed254]

Basic design of these desiccant breathers is shown here: https://diesel-fuels.com/desiccant-fuel-tank-vent-breathers/

I think that when it comes time to 'Recharge' my desiccant with 225F heat I'll be doing in on the outside grill with the top up until I'm convinced the diesel / flammable vapors have been driven off. Flash Point of diesel: http://www.kendrickoil.com/what-is-the-flashpoint-of-diesel-fuel/

Check valves might be good additions, but it makes the design more complicated and I'm after simple and cheap. This one is installed ..... and under test.....as shown in the pics. I will be monitoring desiccant color. If it fails Revision 2 will add check valves.

 

[Chainbreaker]

I've been thinking about an in-line desicant dryer for air lines.

Amazon.com: Le Lematec Desiccant Air Compressor Filter with Teflon, Water Separator, Air Compressor Dryer ZN312-D-C1: Automotive

Buy Le Lematec Desiccant Air Compressor Filter with Teflon, Water Separator, Air Compressor Dryer ZN312-D-C1: Air Dryers - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

Good idea & better yet Harbor freight has exact same filter for $6.99 and they sell refills for it. I'm wondering though how much water it would hold as it appears pretty small, but if its designed for air compressor flow there should be less air flow from just a breathing diesel aux tank.

 

[Zed254]

Bead condition update: all looks good. Beads are still dark blue. Install date was 11/4/20, the first 2 pictures were taken 3/20/21. The last picture was taken some time in 11/20. Post #1 shows a less detailed picture of beads on 11/4/20 install date.

This desiccant breather is working for my application, but I've only got 50 gallons of fuel stored with a very small air gap at the top of the tank. I have pulled no fuel from the tank in these 4 months so the only air movement has been due to expansion/contraction of the air gap.