WVO purging

[dpantazis]

ok, all this talk about keeping fuels seperate has me a bit stymied, or maybe yabbied is more like it.

the issue with switching from one fuel system to the other has to do with contaminating the diesel side with WVO.

assumptions-

• the fuel line pressure downstream from the FPR is under little to no pressure
• we need some means of controlling the path of the return flow of fuel, dino or WVO
• we need to delay the operation of the switching of the return lines of fuel

ok, so i am thinking that there is a SIMPLE solution, and maybe someone has already figured it out and i have not found it yet.

why not use a timed relay to control a SIMPLE 12V 3-way valve- be it a 3 port fuel valve or other? its not under pressure, so it can be almost anything.

i guess i am thinking that a SIMPLE Delay on Make type relay like this one:
http://www.artisancontrols.com/products/2410sa.htm

its a DPDT relay. as i read the schematic, one side is live all the time. the time it takes to purge the fuel from the engine to the tank is the same for WVO or dino.

connected to a 3 way directional control valve- 3 port fuel selector valve would suffice. or half of a 6 port.

so on wvo warmup, flip a switch to power up dedicated WVO pump. relay picks up signal, timer to purge activates, counts down and switches 3 port output after X minutes from dino to WVO.

then, when switching off of WVO, relay pics up the signal, starts coundown again, to switch 3 port back to dino

what am i missing?

dennis

 

[JOAT]

Nothing, some kits do purge back to the WVO tank. Easy to build a time delay for a relay. I can post a link or two if you want to build one, about $4 for a relay and spare change for the delay circuit (a little more to make it adjustable delay).

If you deadhead the fuel system (no return), then you can eliminate the purge return entirely by switching back to diesel several miles before shutting down.

Since you have an SD, you can easily set it up with separate pump and filter for each fuel. With the 6 port (3port if deadheaded) near the engine, natural purge times after switching will be 2-3 miles tops. You can still have a purge valve for fast purges if desired.