The plastic will not hold up to repeated heat cycling with biodiesel. Especially the plastic valves. You need one valve at the very bottom of your tank to drain all the glycerol out. That valve is also used to choke off the pump input when you start siphoning in the methoxide, (which is another ball valve). You will need a valve on a drain, which can also serve as a port to pump in your wvo. So there's 3 so far. One more is good to have pre pump to isolate it when settling and draining. So there's 4 valves. After the pump, I have 2 more valves, one for tank nozzle input, and I close that one off when I pump settled bio into my wash tank, which is another port/valve. So, there's 6 altogether. I have 8 on my drum processor since I use a separate port to draw in wvo from my settling drum. And, I have another port plumbed with a filter on in which I use to pump to my fueling tank after drying. (I also use my processor to dry my washed biodiesel) This sounds far more confusing than it actually is. You can see my processor pics to get an idea what the plumbing looks like at the top of this sub forum under 'pictures of processors'. My current set up is crude but effective.