Pump for KOH

[astrocady]

I am building a unit in a box for a truck application. I need to use a pump to circulate the electrolyte, as I don't have enough height to separate everything.

I bought a Jabsco 12v magnetic plastic pump that was rated for continuous duty, and for "aggressive fluids". After about 30 hours of operation I started having problems. If you turned it off, it wouldn't restart.

Turns out the impeller rides on a shaft that is bushed by a graphite bushing and the KOH started to effect the graphite. It swelled, and I started seeing black residue in the bottom of the tank. I reamed out the bushing slightly, and all was well for about 10 hours then the same thing happened again.

Clearly I need a different 12v pump. Can any of your make a good recommendation? This is for a cross country truck, so the pump will need to operate more or less continuously for 20-30 hours at a time.

Any and all help appreciated.

Steve

[cabrera]

I am building a unit in a box for a truck application. I need to use a pump to circulate the electrolyte, as I don't have enough height to separate everything.

I bought a Jabsco 12v magnetic plastic pump that was rated for continuous duty, and for "aggressive fluids". After about 30 hours of operation I started having problems. If you turned it off, it wouldn't restart.

Turns out the impeller rides on a shaft that is bushed by a graphite bushing and the KOH started to effect the graphite. It swelled, and I started seeing black residue in the bottom of the tank. I reamed out the bushing slightly, and all was well for about 10 hours then the same thing happened again.

Clearly I need a different 12v pump. Can any of your make a good recommendation? This is for a cross country truck, so the pump will need to operate more or less continuously for 20-30 hours at a time.

Any and all help appreciated.

Steve

This is a small 1GPM pump I use to circulate the electrolyte. It's a Shurflo. I bought it on Amazon.com I have about 40 hours on it w/o any issues.

http://www.amazon.com/SHURflo-100-00...7485195&sr=1-1

[BioFarmer93]

Steve, I know this is a little on the pricey side, but I read up on the particulars of the 12V magnetic drive brushless version made out of KOH compatible materials and it looks to be a winner... http://www.rparts.com/Catalog/Major_...77-8930_39.jpg

http://www.rparts.com/Catalog/Major_...umps/pumps.asp

Gus

[astrocady]

Thanks Andy and Gus for your input. I went with the March pump, as it seemed the most rebust and rated for continous operation. I called March and spoke to an engineer there who assured me the pump would have no problem pumping KOH for 24 hours a day.

The pump arrived yesterday, and of course I had to change all the hoses to match the different input and output sizes, but I got it running late afternoon. With one problem.

The pump will be running along fine then for no appearant reason, suddenly slow way down, then slowly speed back up. Voltage remains steady. I left it running all night, expecting to find it not running when I got her this morning, but it was still chugging away, still slowing down then speeding up.

I'll be calling March again as soon as I finish my first cup of coffee. I'll report back.

Perhaps I should have gone with the sure-flo

Steve

[BioFarmer93]

Steve, what did March say about the speed variations?

[astrocady]

I called the distributor I bought it from and they said that was really unusual, as the only problems they've ever seen with any March pump was when someone ran them dry and burnt the impeller. They'd never seen a motor problem. (They are a very large pump distributor and sells many brands and sizes of pumps). After talking with them a while, they send me a new pump overnight. I got it Friday morning. I placed my old pump in the same box and used the USP tag they sent along to ship it back.

The new pump is working flawlessly so far. It even sounds altogether different. It's been running continuously for 24 hours now, and will continue to do so until about noon on Monday. I'd like to run it even longer, but I need to ship the unit out Tuesday and I have to drain it, clean it all up so it looks pretty, and put on warning stickers and such first.

There is one thing about that perticular model that I don't like, however. The motor on the back of the pump is completely open. And it rotates. I had to build a shield around it to protect it from something falling on top of it and stopping the motor. They also make it in a submersible modle, which has the motor fully encased. I don't know how much more it costs, but that will be the one I use next time.