Ever since I first read Graham's instructions for the "Push Pull" processor, I fell in love with it. But the problem with it is the fact that to reverse the flow you need 4 valves, which is expensive and cumbersome. Later on, Graham posted an idea to eliminate the valves by using 2 pumps, which makes it easier to use, but still expensive.
Days ago, I got my first HF pump, and upon disassembly (I always open up new machines), I've got a few surprises: first, the impeller is not made of iron as I thought, but it's actually made of brass. So I guess brass is not so sensitive to BD, after all.
Second, The pump is not centrifugal, but it's actually a regenerative turbine pump (thanks RickDaTech), so its flow is reversible, if you can reverse the motor's rotation.
So I opened up the motor, and after some investigative work, I modified the wiring, assembled it back and tried it, and it reverses beautifully!

So now, for those interested, we can have the "push pull" reactor without all the valves, and with only one pump.

Now, before I give the instructions on how to do the modification, I want to make something VERY CLEAR:

THESE MODIFICATIONS ARE DANGEROUS. YOU HAVE TO WORK INSIDE THE MOTOR, IN A FAIRLY CRAMPED SPACE. FOLLOW THE INSTRUCTIONS, AND ASK QUESTIONS BEFORE MAKING MISTAKES. A MISTAKE HERE CAN COST YOU YOUR LIFE, OR THAT OF YOUR LOVED ONES, SO BE VERY CAREFUL!

Last, IF YOU DECIDE TO MODIFY YOUR PUMP, YOU DO SO AT YOUR OWN RISK, AND YOU ASSUME THE SOLE RESPONSIBILITY FOR YOUR ACTIONS, AND THEIR OUTCOME.

Now that we're clear, here are the instructions:

You'll need:

A ratchet
A 5/16" socket
A 9/32" socket
A flat screwdriver
A hammer
A mini diagonal cutting plier
A hobby knife
A soldering iron
Solder
Wire
Some high temperature insulator
A multimeter
Some epoxy

Now, using the screwdriver as a chisel, gently take off the fan shroud. A couple of light taps with the hammer should be enough.
Put the tip of the screwdriver under the fan, as close as possible to the shaft, and pry it off (gently, please).
Now, take the long bolts off, and with a couple of light taps take off the motor back cover (be careful not to lose the spring washer for the bearing).
Now take off the front cover, which will come off with the whole pump assembly and rotor. Do NOT open the pump at this time, since leaving it closed will protect the impeller from accidental damage.
Now, look for the black wire. Once you find it, you'll see it's tied up to the coils with fabric tape(s). Carefully ( CAREFULLY!!!) cut the tape(s) off, free the wire up, cut the high temperature insulator lengthwise, and get rid of it. Cut the tape(s) as short as possible, to make sure they won't interfere with the rotor when functioning.
You will see 2 copper wires connected to the black wire. Cut them off as close to the black wire as possible.
Now, with the hobby knife (or any other method you like), scratch off the insulating varnish from the tips of both copper wires.
Slide a piece of high temperature tubing on the black wire, and solder it to the thickest one of the copper wires. Slide the insulator over the solder.
Connect a new piece of wire to the thin copper wire, solder it and slide another piece of high temp insulator. Route the new wire to the connection box.
Now,disconnect the capacitor, take a multimeter and test your connections.
You should read about 3 Ohms between red and black, and about 10 Ohms between yellow and the new wire. The reading between both pairs should be infinite.
Now, with some epoxy (I used JB weld), fix both wires to the back of the coil, making sure nothing will interfere with the rotor movement. At this time, take a very careful look at the coils, and make sure you didn't scratch the insulation off any wires. If you did, try to gently separate it from the others (just a fraction of a millimeter), and apply a very thin coat of epoxy over the scratch.
Now, once the epoxy cures, just reassemble the pump. Remember,the wires you just reconfigured go next to the pump side. AND DON'T FORGET THE SPRING WASHER!!!

Now, how to use it.

There are 3 wires normally on an HF pump: black (U1/Z1), red (U2/W2) and yellow (Z2/W1).
Since I don't know which color you'll use for the new wire, I will refer to it as the "new".

You will need to connect a dual pole 3 contact switch to the wires, in such a way that the following connections are established:

For normal running, the new wire should be connected to the black wire, and the yellow wire should be connected to the capacitor.

For reverse running, the yellow wire should be connected to the black one, and the new wire to the capacitor.

None of the other connections will change.

I hope I was clear enough, and you find this helpful. Don't hesitate to post any questions you may have.

Great, well done bernyjb !

Could you measure the flow rates in both directions, with say an 8 foot head of water in each case? Just time how many seconds it takes to empty a container with known volume of water, say 5 gallons.

Also, on an extended run of say an hour, pumping into an 8 foot head, could you measure the pump's case temperature when running in each direction, for a rough comparison of electrical efficiency?

Thank you Graham.
I will measure it soon, but I can't now. I'm having "liquidity issues"
When I got my last paycheck, I went straight to Harbor Freight, so now I'm broke, and the next paycheck goes to pay the rent, so I expect to be able to test it about a month from now.
Anyways, I expect it to have a slightly lower flow in reverse, mostly due to the inlet being in the pump's front face, near the perimeter, instead of in the side, like the outlet. But we'll see. I will post the data when I have it.

Great idea bernyjb, I am in the process of building the push pull now and having four valves around the pump and having all your plumbing connect correctly is a pain. This will make it a whole lot less confusing to operate. If I can figure out your insturctions then I will take a part what I have and do that. Thanks.

Also, Graham do you think you can do a diagram on how it would be on the processor? It makes it a whole lot easier for me when I can see how to set it up.

Graham,
My HF pumps always pop off the cap around the fan and run without it until the fan hits something and shears off all of the blades. After that without any cooling they last for 2 to 3 years of harsh service(I make about 4000 gallons/year)until they sieze and melt. The point of this story is that when the pump clogs I simply turn it off and then turn it back on while (whilst for Graham) flicking the exposed fan blade in reverse. It runs backward and flushes the clog back to where it came from. This worked after the point in the pumps service life when it required a flick to go forward too.

quote:

If I can figure out your insturctions then I will take a part what I have and do that.

Snookup (or anybody else): feel free to post any questions you may have. That way you also help other guys that may have the same doubts, and you help me improve the instructions and my English.

About the diagram for the processor modified for a reversible pump, you can see it here:

http://biodiesel.infopop.cc/eve/forums/a/tpc/f/919605551/m/7211059642/p/9

Scroll down to a little past the middle of the page. You just need to put the pump in place of the 2 pump assembly, and the heater assembly besides it. I would put the heater on top of the pump (between the pump and V5/V6) to avoid the risk of cavitation when the pump is running forward, and leave at least a foot (or more if possible) between pump and heater, to minimize the same risk when running in reverse, but the expert is Graham, so if he disagrees with me, go with his instructions.

quote:

Originally posted by bernyjb:
. . . . help me improve the instructions and my English. . . .

Your English has always been good. I have no problems understanding your posts.

I did not see the reversible processor , was it on that page , or on another ?
Thanks John

JohnTF,
It was towards the middle of the page where there is a diagram and a picture of 2 HF pumps connected so if you turn one on it will flow one way but if you turn the other one on it will flow the other way.

Bernyjb has found a way to do this with just one pump.

Oh and bernyjb I didn't actually read the directions thoroughly untill now and they are pretty clear, before I had just scanned over them.

quote:

help me improve the instructions and my English.

Would never have guessed english wasn't your first language. You are as clear and articulate as anyone and more so than some people I have met who do speak english as thier first language.

Thank you guys. That's very nice of you. And very forgiving.
My first language is Spanish. When I lived in my country, I used to think I knew English, mostly because what I had learned in school, but that opinion was quickly proven wrong once I moved to the U.S., almost 8 years ago. If I have learned some English since, I owe it to the endless patience of most Americans I have met during these last 8 years.
Either way, I'm aware that my English is far from perfect (and it would be much farther from perfect, if Firefox didn't have a spell check), but I keep on working on it, and at least I know I write it much better than I speak it...
But I'm glad you think the instructions are clear. I was afraid they'd leave room for misunderstandings, especially when dealing with electricity.

From what I can see , the link is of the original 2 pump system , no link or pictures of the 1 pump design ?

Hello to all on the forum,

I have been lurking for quite some time, and have been following the a lot of different threads.

The one on using two pumps, back to back seemed like a good idea.

The idea by bernyjb seemed even better. The only question I have is how is the impeller fastened on the motor shaft?

Is it keyed or pinned. If not is there a chance it could spin off the shaft and not pump or spin part way off and lock the pump up?

Again hello to all and back to lurking

BackStagemusic1

I'm with Graham on the temperature of the motor. Reversing the direction of the motor also reverses the air flow from the fan. You might need an external fan to keep it cool.

JohnTF The orignal diagram was with one pump and valves around it to minipulate the flow of the water, then someone decided to put two pumps back to back to minipulate the flow, now Bernyjb has figured the way to do that with one pump, there isn't a diagram with bernyjb's design but you can imagine if there was one pump there instead of two.

quote:

Originally posted by RickDaTech:
I'm with Graham on the temperature of the motor. Reversing the direction of the motor also reverses the air flow from the fan. You might need an external fan to keep it cool.

Making a fan shroud out of a 2 liter soda bottle might work also. That way you still get air flow over the pump either being pushed or pulled across it.

Hello Paul

quote:

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?

Backstage: there's a pin that sticks out of the shaft (I didn't measure it, but I'd say a good 1/8"), that goes into a notch in the impeller, so, short of the impeller breaking in half, I don't think it could loosen up.

Rick: actually, the fan works similarly to the impeller: it pushes air to the perimeter, so I don't think there should be any cooling issues. If the motor gets hotter in reverse, I think the culprit may be the inlet of the pump, which instead of being located in the perimeter, like the outlet, is located at the housing's front face, about 3/8" from the border, so it might take some extra power from the motor to move the liquid. But I've been looking at the pump housing, and I think, if necessary, the priming hole could be over bored a little, and used as the inlet/outlet, instead of the original inlet.
I haven't tried it yet, because first I want to test the pump as it is, but if I see any flow or temperature problems in reverse, I will, and I'll report on the results.

JohnTF: Snookup is right. You just replace the 2 pumps with the reversible one, and install the heater after it. In my opinion, the best location for the heater should be between the pump and V5/V6, but I'm waiting on Graham's expertise on the matter.

The HF cooling fan will blow air across the motor when turning in either direction. It's a straight-vane centrifugal out-flow impellor with duct shroud that directs the airflow along the finned motor body.

The pump impeller is keyed to the shaft, and the fan is an interference press-fit, so there's nothing to unscrew. Good thoughts though.

Good news about the fan - looking promising!

The other possible overheating issue could be due to the way the motor is wound/rotor is shaped, being electrically/mechanically more efficient one way than the other, but being a low cost pump, I'd guess everything is symmetrical and will have the same efficiency either way - still, would be nice to know if it keeps as cool, both ways.

As to the location of any inline heater, this adds a little more 'interest' to the layout...

The heater should be in the outlet side of the pump. This is because we want the inlet to the pump to be as cool as possible, to minimise the effects of cavitation (Because the inlet is at low pressure, the methanol will boil at lower temperature), and the liquid in the heater to be in the higher pressure section of piping, to reduce boiling risk in the chamber.

Also it would be a little kinder on the pump not to feed it with the hottest liquid in the system.

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?