2 tankin .. when you know you have purged

[Prickle]

Chaps

Set up a 2 tank system .. what's the go on knowing when you have purged all your oil out of the system and switching back to Dino? I realise it may be a bit of rough science but it would be handy to know when the system has been cleared

I thought maybe you could colour the dino with a food colouring so you can definitely see the change from oil to dino ... any other thoughts

Stuart

[Prickle]

Re: 2 tankin .. when you know you have purged

.... Some people say they never forget to change back but a lot more mere mortals do forget at times so knowing how long you have to idle to purge once you sityting in the driveway could also be handy. I figured out how many laps of the block it takes instead.

Ain't that the truth ... went out this morning and back home and forgot to purge ... parked it in the yard and let it idle until I couldn't smell fish & chips and I knew the deed was done .. Too easy

Stuart

[tbird650]

Re: 2 tankin .. when you know you have purged

what's the go on knowing when you have purged all your oil out of the system and switching back to Dino?

VE rotary pumps ...1.5 - 2mins as a basic rule for minimum. My setup has separate feed and return valving which helps greatly to minimise cross contamination. When switching to dino, the return gets the flick 1.5 - 2mins after the feed. This means a small amount of dino goes to the veg tank but that's better then veg in the dino tank. For timing I simply used the onboard clock. It doesnt matter much if it's idle or roadspeed either because roughly the same amount gets returned to tank.

For switching to veg, I use a different time lag. Return gets switched 30secs- 1min after feed.

Have a great xmas.

[Nuddy]

Re: 2 tankin .. when you know you have purged

Simple answer:
When the engine starts as if it were on Dino all along.

That is about the best guide to use. I would suggest start off with a landmark say 3 Km from home. Switch over and see how it starts in the morning. If it is fine, try switching over a little closer. If that is fine, shorten the distance again and so forth till the speed of the start falls off and takes longer to crank then go back to the previous point or a little before for good measure and there you go.

I read of one guy who lived on a country road that got some of that fluro paint and marked a road post so when he saw it, it jogged his memory ( and his mrs.) to flick the switch.

If you have several approach paths to your home as I do, you'll get a feel for each route soon enough. My markers are simply the next suburb from home but I live in the city and for some people the next town could be 50KM away! You can probably start your purge a bit closer than that!

You might also want to try an idle purge test. Some people say they never forget to change back but a lot more mere mortals do forget at times so knowing how long you have to idle to purge once you sityting in the driveway could also be handy. I figured out how many laps of the block it takes instead.

I tried the colored oil ( Tranny Fluid) approach and it didn't work at all.
I think the filer setup just tops the filter up and the excess is returned so even when the return line clears, the OEM filter is still full of the last fuel to pass through it. Your setup may be different but just illustrating the fault I found in the method you describe which I also thought sounded logical but didn't work in practice on my car.

Remember, despite all the hype, You don't need to change over at the last possible second. the purge fuel dosen't drop out on the ground and you still get to use it. Some people seem possessed with changing to oil at the soonest possible second and purging between the time they put the transmission in park or neutral and turn off the key.

No harm in taking a little extra time in changeover either way but cutting these things short holds a lot of potential danger.

I found my patrol starts exactly the same on 100% diesel and on 50/50 WVO/Diesel. So if the only requirement is easy starting then the above method would work fine. However if a complete purge is required (IP completely filled with 100% diesel) then a much earlier switch over will be required.
For me it is only the starting that matters but some have a 'thing' about WVO in the IP overnight.

PS Merry Christmas to all.

[Tim-HJ61]

Re: 2 tankin .. when you know you have purged

I tell by the colour of the exhaust when I blip the throttle.

Full vege - minimal smoke.
Partial purge, grey smoke.
Full purge, black smoke = diesel.

Being a DI, I'm most concerned about vege gelling in the injectors, so seeing what is in the IP is not as relevant as what is in the injectors.

Of course, if the injectors are full of diesel, so must be the IP

Tim

[hobie1kanobie]

Re: 2 tankin .. when you know you have purged

hey all,

purge time. does this not depend on how long a run of fuel line between switching valve and ip?

my way of thinking is, to take as long as you think is required. i have certain points on any given direction home, that i can switch over and have no worries. i am in no hurry to see how short a distance before change over.
i figure that, wco is not costing me anything, so the amount of money i save on running around, by far out weighs the cost of a few extra meters of dino travel time just to be sure.

just my 2 bits

H1K

[Nuddy]

Re: 2 tankin .. when you know you have purged

hey all,

purge time. does this not depend on how long a run of fuel line between switching valve and ip?

Not quite that simple.
Trouble is there is mixing in the IP.
If you get 50/50 mix in the IP it will probably start perfectly well next day so you will think you have fully purged.
If your concern is more than just starting next day then Tim's method (smoke colour) will be a better indicator.

[joe]

Re: 2 tankin .. when you know you have purged

Not that i can't provide the answers; so I'm relying on anyone who can fill the gaps, but we are talking about replacing the volume of WVO with the volume of Diesel (in this case but may more likely be biodiesel).

The equation would go as follows;

the volume of the liquid in the tubing from the change switch, filter (if applicable), IP, IP lines to the injectors (or what ever your set up may be);

MINUS the amount that injects into the engine and is consumed
MINUS the amount that is returned to the tanks
ALLOWANCE for gradual dilution of WVO in IP before being pressurised in IP lines (which I guess would be different to just a set amount of fluid to be replaced)
Amount that is pumped to IP from lift pump or what ever pumping method there is.


For example in the first minute of flow, it the ratio in the IP may reduce to 30/70 D/WVO (Diesel/Waste Vege Oil) ratio. In the next next minute it may be 40/60 D/WVO, in the next minute it may be 50/50 so on and so forth until our ideal starting amount is reached. Which in most cars is probably somewhere around 15 - 30 % IN SUMMER and considerable less for winter. And for the sake of arguement it may not and most probably does not reach ever 100% diesel. Even with 15 minutes it may still only be 99%. Who knows.


I guess an easy way to definitively say how much fluid must be replaced (which may not take into account the gradual dilution issue) is to say how much fluid is being used per injector squirt x 4 x rpm PLUS the amount thats being returned to fuel tank. (This could be diverted to a empty tank and measured).(plus fuel leaks)

So to take the equation further.

lets say there

• is 80 mls in the lines from the switch to a filter

• is 50 mls in the filter (which also acts as a dilution point)

• another 30 mls in the line from the filter to the IP pump

• is 500 mls in the IP

• 80 mls in the IP lines x 4 (but I'm not sure if this counts as they SHOULD be used at the same rate but I guess its a total amount so we'll count it

• 5mls per injector x 4

So lets say for arguements sake (bloody hell its added up to 1 litre, that was a fluke) that there is 1000mls.

I cant find the exact amount of fuel delivered per aquirt but for an 85 4d55 (2.3Ltr) Pajero, which was my test bed for Biodiesel, I believe the amount was close to .02mL ( and .025ml for a 4D56 (2.5Lt). Please its just an exercise and its a rough guess I cant find the figures.

So multiple .02 x 4 x rpm (of say 2500rpm) equals 200 mls of fuel being used in one minute of operation. How much over flows ??? Any one every measured it?? Lets say its and equal amount 100mls per minute for arguments sake. AND I DONT WANT TO ARGUE THIS UNLESS IF MATHS ARE WAY OFF. These are guestimates.

Also at 2500rpm in 5th you'd be doing approx 100kph and in 5 minutes ( 1 lite of fuel consumed )travel you'd get 8.5 k's. ( so my maths are a little by about a 20% assuming my old pajero RIP is getting 10k's to the litre )

Lets say in one minute of operation we have used 200mls of fuel and there has been 100mls of IP return.

Lets say that 300 mls of DIESEL have entered the Fuel system from the switch. We now have close to D30 (or 30% diesel and 70% WVO) Most if not all of the lines would be completely flushed. But the IP be close to D30.

In the next minute, lets assume the diesel mixes and swirls perfectly and we have an even d30 mix through out the IP and not pockets of WVO and 70-80% Diesel.

In this minute 200 mls of D30 fuel are consumed, 100 mls of D30 are return to the tank and another 300 mls of diesel enters the IP. Whats the ration now.

Who the hell know but you get my point, if your still reading. God am I still typing!!

Lets keep it going then. If 300 mls of diesel is added to 1 litre of D30 it would increase the ratio by a third to approximately 50% (am I wrong any takers? please jump in any maths gurus)

In the next minute 300 mls is used or returned and 300 mls flows in. Further increasing the diesel ratio by another third to 65%, seemingly taking exponentially longer to attain 100%. I lost interest after the 4th minute. I thought it was only 70% but that didn't seem right. I'm sure after 4 - 5 minutes the IP would be closer to 90 - 95% diesel, thus proving a more friendlier cold start fuel.

And if your STILL reading go get a life!!

Any corrections? Maths graduates need only apply?

[Prickle]

Re: 2 tankin .. when you know you have purged

And if your STILL reading go get a life!!

Thanks Joe ( I think ) posted at 1:24 am ... lets hope you work night shift ... I'd hate to have all that rattling around in my head at that time of the night

Food for thought

Stuart

[Alga]

Re: 2 tankin .. when you know you have purged

Both my triton and 2h hj60 cruiser take 2 klms to purge, any less than that and I have trouble starting next day no matter the weather. It makes no difference whether I start of BD or dino, although during winter BD is not as reliable a starter as dino unless blended. One engine has a return line and rotary pump the other in line and no return, you'd think they may take different times for purging, but that doesn't appear to be the case.

As for starting, I switch over as soon as the engine is running and by the time the dino is purged, the engine is hot enough to accept WVO and I idle it for at least 5 mins before driving so as to not put any strain on the motor with thick oil under high torque.

Luckily I'm mathematically challenged, or I may have got troppo reading Joe's post.

[hobie1kanobie]

Re: 2 tankin .. when you know you have purged

Might go process some oil today.
That setup has been working perfectly well for a long time now so I better go screw round with that as well and see If I can't do the same thing another way or just re-confirm I have already got it as good as it's practically ever going to be! 3rd January 2009 09:59 AM
maaaaaaate,

just this last week end, i got bored. thought about trying to better my filtration process, to make it easier on my already getting worse back problems.
left the main upflow tanks alone, mainley cos they are full, so started by removing my pre strainer and my two 5micron pre upflow filter drums and maybe in the process, stop some of those annoying little leaks.

well all started out pretty well, drained off all the residual oils in all pre filter drums, disconected the hoses and started again.
talk about opening a can of worms.

my first pre filter, the shopping bag 1, had sooooooo much gunk in the bottom, water and some other crap, that it had actually started to smell REALLY BAD. i mean this stuff was putrid.
wife comes out, WHAT IS THAT HORRID SMELL?
i did not think this possible, considering that it was under so much oil, thus away from contact with the air.
turns out, some of my oil collected had come from some Indian Take away shops and the herbs and spices had fermented. this stuff was toxic.

so after spending some time back here looking for an answer, i came upon someones cleaning tip, of using a solition of koh in a spray bottle.
again what a mistake, i mix a solution then add some more cos i really wanted it to work, and then proceed to spray the drums, the walls and any other thing that was sticky.

left it for a while, (like 2 or 3 beers for a while) thinking that this would be long enough. LONG ENOUGH???
what have i done,
my drive way has a new colour, the grass will never ever grow again, i am up for a new garden pump spray, wife is not talking to me cos the driveway has changed and she now has to wait for the garden spray and god forbid anything else that came in contact with the spray..

i have learnt a very serious lesson, IF IT AIN'T BROKEN.. DONT MUCK WITH IT........
cos by Sunday, i had put it all back to the way it was. yes i have put some more oil through the system, yes it still has those small annoying leaks and YES my back still hurts, but atleast it WORKS.....

cheers,

H1K

[Johnnojack]

Re: 2 tankin .. when you know you have purged

....
I'm going to experiment with looping the start fuel return so no veg gets into the Bio tank. I want to see if this will increase the purge time/ Distance or not and if it is possible to save a bit bio with a different changeover strategy through not diluting the start fuel with veg.
The main aim is not to get frugal with the start up fuel but rather to let the gradual dilution work in my favour at startup and end up with more pure purges while still being able to use the same convinent markers as I do now.

I looped my start fuel a while back and am happy with it that way. (See note below.) My diesel tank does not get gradually turned into a oily mixture of indeterminate percentages. By delaying switching of the return I can still flush back to the vege tank so ensuring a faster purge. Then when the return is switched the blend in the pump goes round and round while increasing in diesel/bio content. I only know it works because I get instant smokeless starts. However what the percentage of vege left in my IP is a bit of a guess.

*Note while the start fuel is looped, when switching from diesel to vege, if the return switch is delayed diesel can return to the tank via the feed line. I only do this after doing a few short trips on diesel only, as I then am confident that for a minute or so only diesel will be in the return. Otherwise I switch the return at the same time as switching to veg. Veg is looped as well. Clear as mud?