Hello all. I too have been lurking for the past month or so and we're in the process of building. Thanks to everyone for such an open source of invaluable knowledge and interaction.

Looking at the process and the times during which more heat needs to generated (de-water/meth), would it be better to place the heater below the pump to avoid issues?

V5: w/ eductors for mixing
V6: filling & reverse intake
V10: reverse output

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Now this may not be a big issue with a regenerative pump, but it is bound to have some influence, so can you think of a way of keeping the heater always downstream from the pump?

Hmmm, that would be like finding the end of the rainbow...

But no, I've been thinking about it, and since now the pump switches inlet and outlet, short of installing a bunch of valves again, or 2 heaters, which in both cases would defeat the purpose, I don't see how it could be done.
But there's a way this could be, if not completely avoided, at least minimized.
What we could do is install the heater as Jdoughy (thanks) suggested (between the pump and V10), and run the process in reverse (same as in the demething step) for the oil preheating/dewatering step ( step 3). That would mean putting the V6 inlet a little lower in the tank, and it'd probably make dewatering a little slower, but at least the heater would stay at the pump outlet when functioning.

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Originally posted by Tilly:
Hello Paul

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Originally posted by paulb3:
Making a fan shroud out of a 2 liter soda bottle might work also.

The World Famous Dr Pepper Fan Shroud?

But of course! I keep forgetting the versatility of the amazing Dr. Pepper Bottle tho I perfer Pepsi.

Is that little Harbor Freight pump large enough for the push-pull processor?

I thought the pump had to be capable of running 1/2 batch volume /min.

I'm building a 80gal tank, so allowing a large head space yeilds 60gal per process. That would mean a minimum of 30gal/minute pump rate is recommended.

The Harbor Freight is only rated at 640gph MAX, = 10.66 gpm, only about 1/3 of the minimum size pump Graham recommends, and that is at maximum output.

Are you guys using this pump on the push/pull? If so, what size batches are you running, or maybe do you let it pump for a longer amount of time??

I am attempting to get all my parts together and begin construction next week, so any reply would be great!

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Is that little Harbor Freight pump large enough for the push-pull processor?

No, for most processors, it isn't. But the advantage of the HF pump is that, being so cheap, you can use more than one pump, which has the disadvantage of making the plumbing more complicated, but in exchange has the big advantage that if one pump fails, you don't have to stop processing.
I'm planning on building a 30 gallon push pull, and using 2 or maybe 3 pumps.
By the way, if you want to make 60 gallon batches with an 80 gallon tank, you won't have much head space at all. 60 gallons of oil + 22 % (13.2 gallons) methanol will give you less than 7 gallons head space (actually, probably less than 6, if you count the lye).

wouldn't it simply be easier to use a 150 dollar variable speed drive?

A VSD would be useless. Motors like the one the HF pump uses can't be reversed externally, and their flow can't be increased that way. The only possible way to (slightly) increase its flow would be to use a variac, and that at the cost of severely decreasing the pump's lifespan.
Besides that, with the additional $150 expense you'd be able to buy 5 extra pumps, or 4 and the extra plumbing, which is an increase in flow, and reliability, you can't possibly get any other way.
The idea here is to get the highest possible "bang for the buck". Of course there may be better options, if you have the money to pay for them, or if you're willing to.

Hello Berny

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Originally posted by bernyjb:
A VSD would be useless. Motors like the one the HF pump uses can't be reversed externally, and their flow can't be increased that way. The only possible way to (slightly) increase its flow would be to use a variac, and that at the cost of severely decreasing the pump's lifespan.

If you re-read Dogma's post he was not talking about the HF Pump, he was talking about a $150 variable speed drive motor.

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Besides that, with the additional $150 expense you'd be able to buy 5 extra pumps, or 4 and the extra plumbing, which is an increase in flow, and reliability, you can't possibly get any other way.

How does buying 5 Piece-of-Crap pumps increase reliability?

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The idea here is to get the highest possible "bang for the buck".

"Bang for the buck", a good choice of words!

so what really needed is a spur gear pump driven by a DC motor.

-dkenny

you have to be careful with DC motors, there are a number of DC motors out there that are not continuous duty rated.

this might end up being a repost, but, the message board appears to have eaten my first post.

So, to summarize - Thanks Tilly - That's what i was talking about. A good solid 3phase motor.

and I've always been of the mindset that its better to invest in quality in the beginning as it will invariably produce more consistant results and generally result in fewer headaches and less unnecessary out of pocket expenses.

Tilly, your constant harping on the HF pump is amusing. I've been using the same pump for 4 years now, processing over 1500 gallons of fuel (oops, that's almost 6000 liters for the SAE impaired). My last batch failed 3/27 badly and I noticed the pump was slow -- I took it apart and found some plastic shavings blocking the inlet -- from a settling barrel. I cleaned out the pump, I checked the electricals, found no signs of wear. The pump is back in service. So far this is an extremely reliable pump.

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so what really needed is a spur gear pump driven by a DC motor.

Wouldn't that be perfect...
Or at least, the same pump with a DC motor. And for the same price, please...

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....flicking the exposed fan blade in reverse...running the pump in reverse...

I'm surprised that i haven't thought of that. I've had an HF pump that upon initial plugging in will pump backwards unless you dangerously "half" plug it in and spin the impeller the correct direction. I'd replace it but i'm too cheap and it only receives intermittent use as a fueling pump. It's been that way for almost a year now and has no problems in operation.

I wonder if the same thing can be done with the more reliable, higher GPH Northern Tool pump?

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Originally posted by ProjectPurity:
I wonder if the same thing can be done with the more reliable, higher GPH Northern Tool pump?

This will only occur if the start-run capacitor is defective.

ReM

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I wonder if the same thing can be done with the more reliable, higher GPH Northern Tool pump?

If you're talking about hand cranking it as you described, I wouldn't try, defective capacitor or not.
Now, if you're wondering about modifying it...maybe. If you want, disassemble it (I don't know if it's similar to the HF). Look first at the impeller: if it's a real centrifugal pump (if the inlet goes straight to the center of the impeller), it's NOT reversible. If it's like the HF, take a look at the motor: if you have 2 copper wires connected to one of the terminals (the one that's NOT connected to the capacitor) you should have no problems making it run backwards.

the NT pumps will backwards just the same as the harbor frieght pumps.

its easy..if you don't mind a manual start...
just disconnect the cap. then spin the fan in the direction you want the pump to go. I did this for a couple of months until finally replaced the cap. I only need the pump to run one direction, but would run either


DC motor would have to built.
doesn't require much. find a spur gear pump.
a used DC tread mill motor( ebay).proper coupling pieces. and you're off..
great flow in both directions

Rob_ - you'll want a much bigger pump. for along time I ran a 1" NT and 1.5" NT pump..then I went to goulds 60gpm pump...much better. better seal, better temp range. I don't think it reversible.

-dkenny

Sadly I haven't done the math yet, but I figured I would start with 60gal total volume in the reactor and work backwards to determine how much oil / lye / methanol and what the final biodiesel output would be.

The tank is 80gal, if I should shoot for 70gal max fill instead then I'll do that.

Well I was going to hit HF and stock up on supplies, but it sounds like buying the murphy's machine big boy would be a better route for the size I'll be running.

This forum is great, thank you to everyone for your knowledge, experience, and willingness to teach others.

Hopefully I'll be able to pick up the tank and piping this weekend to get started on it next week.