quote:

it'd be better to have too little acid (even if the lye is not fully neutralized) than too much.

That is true, and when i mentioned that an indicator solution that would change color at a slightly less acidic point would be better for this. I forget if turmeric does that or the opposite.

The important part is to get a representative sample in the site tube, because if it isn't a constantly accurate sample of the whole batch, you will end up with a false reading with the indicator.

quote:

All I can say for sure is that if my heaters leak, I am doing away with the horizontal safety feature and putting it vertically. Ok enough gripping.

You'll sure gripping when your shop burns down or the tank explodes with you in the room. Accidents happen and methanol fumes trapped in an area with an exposed hot element spell trouble. Why didn't you just have a couple 1 1/4"NPT x 1"NPT bushings welded into the tank like i did? weld them in close to the bottom so that you don't have to build a thing like that... That being said, i do like Graham's external heater design for what it is.

quote:

Just spent 11 hours teflon taping and tightening my main plumbing. Sadly I still have to do the foam trap and the centrifuge piping. I hope I am not doing anything wrong, I had no idea it would this long to plumb.

Unless you've NEVER used black iron pipe and teflon tape before, it shouldn't take that long. You just need two pipe wrenches a bunch of teflon tape and an idea of what you're about to build. After the specifics spelled out in this thread, you should have your work made easy for you.

Also, you should pressure test with the garden hose hooked to your processor on one of the upper outlets, letting a vent open at the top. When the tank is filled, close the top vent and allow the pressure to build. you'll notice any pinholes in your welding... fix them now rather than later with either JB Weld or more welding. A garden hose should do at least 10-15lbs... which should adequately leak test your tank.

Take it easy.
JB

Is there such thing as having the rapeseed tank to far from the processor?

Right now the way I have the rapeseed tank is around 28-30" away from the processor. Just trying to figure out if I should make adjustments or if it will be alright where it is.

Ted

The only reason that i'd see for it to be closer would be to prevent reflux, but if you insulate your piping, it shouldn't be a problem.

My 2 Cents though.

Thanks project,

My pipes are insulated so I will let you know how it goes.

Ted

quote:

I forget if turmeric does that or the opposite.

Opposite. Anthocyanin from red cabbage is a universal indicator with a range of colours indicating the PH you are at. Not sure how well it would work with this whole batch titration but it works very well on our normal titrations.

This message has been edited. Last edited by: Ant,

After reading about the Push/Pull processor I decided to build one. I bought a 120 gallon propane tank, and burned off the fumes.
Now I need advice on what pump to use. Around here a 40 gallon per minute pump is considered an irrigation pump,typically with 2 inch fittings.Can I get buy with two Northern Equipment pumps in parallel? That would only give me 20 gallons per minute max flow. Would putting some kind of 'turbulater' after the pump allow me to get by with less flow?
Sorry about all the questions but I can't move forward until I get the pump question answered.

Thanks
Dave

Pump mechanics was by far the hardest thing for me to understand, and for putting pumps in parallel, you are already beyond me. However, what I do know, is the best pumps for the money are: the 1.5hp Murphy's pump Murhpy's Machines or pumps from Grundfos. Grundfos is the pump pictured in Graham's Eco1, and they are plentiful in the US as they are used in Floor Radiant heating systems. They also come in different metal flavors, the cast iron ones are a bit cheaper than the Bronze ones. The good and the bad is that they come in 20-30 different sizes with numbers that have a pattern but do not specifically indicate anything - maybe I am missing something. But you will need at minimum two 26-99 to move the flow at 60 gpm or they have bigger pumps, but they are not common and are more expensive. I am including a PDF from their website - look at the graphs starting on page 28 onward to get an idea of what the flows will be. As you probably already know, Head is the measurement of pressure the pump can handle and is measured basically by calculating how far the TOP of your liquid is being moved - (Not the bottom - this took me a little to wrap my head around). The top of of the liquid in the processor is only moving a few inches, so Head is nearly 0. However, the pipe friction and twists and turns does create some Head - how much I do not know as there is one website that has a calcualtor that after I used it reported I had like 100 feet of it - which seems impossible. 1" pipe creates a lot less friction than 3/4" so use it if you can afford it. Check back a few pages to find that guy on ebay who sells 1" Ball Valves at the best price I have ever seen. Also check ebay for these pumps as you can usually find a someone who has 1 or 2 spares from some large install. Hope this helps.


Doug

Thanks Doug,
I decided to buy the pump from Murphy's Machines. I need to learn alot more about hydraulics in order to make an informed decision. I did learn that each 90 degree angle is equivilant to an additional ten feet of pipe. How this relates to head pressure or flow ratings I don't know. The people at Murphy's assure me that a 1.5 horsepower pump is adaquate so I'll trust their expertise.

You already are on are you way to understanding.

I think engineers do not use pressure because there are many factors that effect pressure that have little to do with the pump itself. So in the end, they just measure how high the pump can lift water at a certain temp and measure that - calling it HEAD. Then calculate how much HEAD other elements add - 90 degree angles, size of pipe, friction of pipe, viscosity of other liquids to come up with a total for HEAD.

The only thing that was news to me but obvious after thinking about it was to measure HEAD from the top of the liquid being moved, not from the pump itself - which in my setup was at the bottom.

A simplified explanation is that liquids themselves, gravity and atmospheric pressure act together as a kind of pump that pumps the liquid itself to a certain height - equally through the system - regardless of the size of the pipe. Its one principle of EQUILIBRIUM THOERY and there has got to be a simple name for it, but I can not remember it. Think of the liquid in a straw, its the same height of the soda in the cup just like the liquid in your 1/2" site tube is the same level in your 120 gallon tank.

The result is that the pump will then only have to move the liquid higher than the liquid can do it by itself - thus measure from the top of the liquid to calculate HEAD not where you place the pump.

Hope that makes sense and is not too wordy.
Doug

quote:

there has got to be a simple name for it, but I can not remember it.

There is. They're called "Pascal vases".

http://www.ph.utexas.edu/~phy-demo/demo-txt/2b20-40.html

Doug,
Your explanation makes perfect sense.
Thanks

quote:

Originally posted by Hummerbk:
Thanks Doug,
I decided to buy the pump from Murphy's Machines. I need to learn alot more about hydraulics in order to make an informed decision. I did learn that each 90 degree angle is equivilant to an additional ten feet of pipe. How this relates to head pressure or flow ratings I don't know. The people at Murphy's assure me that a 1.5 horsepower pump is adaquate so I'll trust their expertise.

In large centrifugal pumps, allowing them to run against too little backpressure (too little head) can destroy them through cavitation. I doubt that low pressure operation will be an issue with a 1.5 hp pump, but apply the common sense that consulting engineers often lack - a pump which is discharging into the same reservoir from which it is drawing, does not experience very much head.

So Jeff, do you think I should use one inch pipe instead of 1 1/4 to slightly increase back pressure?Do you think one inch will reduce the flow too much?
For some reason I thought cavitation was caused by not enough flow into a pump.

Graham, this design is brilliant. I've been lurking for quite some time, but have been a little concerned about the shop space required in ancillary equipment for an appleseed processor, as well as the somewhat large batch size an appleseed implies.

I would like to do this, but I'd like to scale it down for my current needs. (I burn about 5 gallons a month in my tractor) Would an eco-processor work adequately with a tank of about 9.4 gallons capacity (I have a 40# propane cylinder) and a 1 gallon propane cylinder for a vacuum tank? I estimate that This setup could fit in a 12 x 24 x 48" tall.

I understand that 5 gallons a month doesn't justify the financial investment in any processor, but I can justify some expense from a hobby perspective.

If my needs change to the degree that the 8 gallon batch size is inadequate - I can always swap the valves, condenser, pumps and vacuum tank to a larger (waterheater-scale) processor.

What say you?

quote:

Originally posted by Hummerbk:
So Jeff, do you think I should use one inch pipe instead of 1 1/4 to slightly increase back pressure?Do you think one inch will reduce the flow too much?
For some reason I thought cavitation was caused by not enough flow into a pump.

Cavitation is caused by vacuum bubbles which form (then quickly collapse) in the low pressure area at the eye of a centrifugal pump.

In a >5hp non-self-priming centrifugal pump pumping water (the type with which I'm familiar) The ways to avoid cavitation are:
a) do not throttle the suction - provide as unobstructed path from the reservoir from which the pump is drawing as possible.
b) pumping cooler material is better.
c) assure that the pump is running on a good spot on its performance curve. Running against zero backpressure is generally not good. A centrifugal pump is generally happy running near shut-off head... but it's a poor use of electricity.

That said, the rules for big centrifugal water pumps are not be very applicable to the experience of small pumps in oil, if for no other reason that unlike water, vegetable oil has a vapor pressure of about zero. In other words, most pure vegetable oils can exist in liquid form in a vacuum and thus resist cavitation.
http://www.engineersedge.com/fluid_flow/fluid_data.htm

(FWIW, I'm unconvinced that the small HF pump is not a classic centrifugal pump)

Kind of a long winded way of saying that I'd use the 1 1/2" dia pipe because after consideration a) I don't think that cavitation is an issue for these little oil pumps.
b) It's important to have a free suction flow as possible
c) I'd rather drain the glycerol through as big a pipe as possible.

quote:

(FWIW, I'm unconvinced that the small HF pump is not a classic centrifugal pump)

It's not. The HF pump is a "regenerative turbine pump". You can look it up here:

http://www.roymech.co.uk/Related/Pumps/Peripheral%20%20Pumps.html

BTW: what does FWIW mean?

quote:

Originally posted by bernyjb:

quote:

(FWIW, I'm unconvinced that the small HF pump is not a classic centrifugal pump)

It's not. The HF pump is a "regenerative turbine pump". You can look it up here:

http://www.roymech.co.uk/Related/Pumps/Peripheral%20%20Pumps.html

But the HF pump draws suction directly into the eye of the impeller, like a centrifugal.

Does anyone have a published performance curve for the HF pump?



Every pump with a curve that looks like the one on the left is a centrifugal pump.

quote:

BTW: what does FWIW mean?

FWIW = "For What It's Worth".

http://www.gaarde.org/acronyms/?lookup=F

quote:

But the HF pump draws suction directly into the eye of the impeller, like a centrifugal.

That's what I thought, until I bought my HF and opened it up. The intake is internally routed to the impeller's perimeter. I guess they did it that way so you could use the pump as a replacement for a centrifugal with minimum or no re-plumbing.

quote:

FWIW = "For What It's Worth".

Thank you. TWDMC ( that's "That Was Driving Me Crazy" )

Hi

Can someone tell me (Graham ) what the line marked with the red arrow does ??

Also when in stage 7 and you are applying vacuum to the reactor is there enough air going through the system for the condenser to work ... ie where / how does the replacement air enter the system?

Thanks

Stuart

It is a small pipe to prevent a rupture if the heat is on while the valves are closed, here is a quote from GL's site: "It has a failsafe narrow bore relief pipe, so that if heat is applied with all valves accidentally closed, it will prevent over-pressuring / rupture."
In stage 7 the reactor needs to be under vacuum therefore there can be no air entering the system. The vapors in the system will migrate towards the source of the vacuum as the methanol boils off through the condenser.

Best regards,
Jon