The best way up to date to heat the tank near the outlet?
If a limited loop return is used a small temp regulated 12v electric heated outlet.
I don't think these are commercially available so you would have to design and make your own.
This provides for rapid melting of any solid VO until the hot return fuel begins to do the majority of the work.
In most cases a coolant heated outlet is the most practical.
In any case do not design a tank heater that adds so much heat to the VO in the tank it creates conditions where rapid polymerization is likely.
I think my IP doesn't tolerate any pressure as there is no pressure to the inlet of the pump, it pulls directly from the tank.
It is better to provide a very low fuel pressure at the inlet than require the IP to pull a high vacuum.
Isn't it better to look for the dye in the IP outlet (return line) , then you are sure VO is out of it too.
I don't think so since the return line from the injectors will clear of VO after the IP is cleared.
Also in what way do you recommend having the return line? Having another valve with a timer for the return lines like seen in some places? Just have it regularly returned to the VO tank (then you lose the diesel when running on it)? Isn't it helpful to have the already hot returned VO back into the IP?
During shutdown there are not any other practical options other than returning the diesel/vo mixture created during the shutdown purge cycle to the VO tank. Returning that mix to the diesel tank will create engine longevity problems.
I believe the best option is to return some of the VO to the VO tank while operating on VO to allow any air bubbles to be purged
while recirculating most of the already heated return VO to the IP. This is referred to as a limited loop vo return configuration.
Does settling eventually get the suspended water out?
Eventually yes...as long as the VO is fully liquid and not gelled.
Will a titration be helpful in determining if the VO is good enough (water-less) for use?
No. Titration does not reveal water in VO fuel.
My oil titrates at about 0.4-0.5 ml , tested it like shown here :http://journeytoforever.org/biodiesel_svo.html#titsvo , according to them it means my oil is probably dry enough. Is this method of testing relevant in the use of WVO as fuel?
Titration is not highly relevent..water content is.
Also read about WVO oxidation and possible damage to engine internal parts and bought some oxidative stabilizer for WVO , is this really necessary?
There are different compounds sold as stabilizers. To date none I have tested have been especially effective. The most effective thing you can do is to make your wvo as water free as possible and not store wvo for long periods of time prior to use.
Still trying to figure out the best method to have the fuel return line setup . Currently both diesel and VO are looped back to the inlet side of the IP , i don't think i have air accumulating in the system since i dont seem to have any loss of power and according to some reading in this forums there usually isn't any problem with to much heat to the VO or Diesel since before the IP as it mixes with the fresh fuel.
I still want to at least unloop the diesel so i have shorter purging time . I Have a six port valve but currently only using three ports.
I think unlooping diesel is a very good idea.
My Heat exchanger is before the filter, but i am thinking on having the heat exchanger the last thing before the IP, good idea?
Always have some kind of filter between the HE and the IP. Even a small disposable "Chunk catcher" is ok. It too will have to be heated (a simple hose jacket will work) to liquify any VO in it in cold weather.
Also on the harness i bought from you the relay has a spare unused blue wire , could i connect it to the solenoid valve? I want to combine the switches and relays to simplify things a bit.
The blue wire is hot when the solenoid is "switched off" but the key is still on. I use it to operate solenoid valves in multi valve or timed configurations.
Hope this helps...and sorry I missed your first post. I am now semi retired...retaining only a single large client and so am travelling more to places that have no internet service.