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"Unidose" chemical feeder pump - Who is Brer Vole?

Nov. 8th, 2014

02:58 pm - "Unidose" chemical feeder pump

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Purchased a chemical feed pump to help correct the pH of my well water. This is done by injecting a small (and precise) amount of basic chemical into the pressure tank while the well pump is operating. For the pH correct to be correct - the well pump and chemical feed pump need to pump at the same ratio. I estimate that I need a 1:1000 injection ration of a ~10% solution of "soda ash".

The Unidose chemical feed pump is offered as such a pump - and at the best price. Unfortunately, it doesn't meet the requirements. My first test (a very crude one) found that a few feet of head resulted in a very different amount of fluid per pulse. I contacted the manufacture (LMI) who interestingly couldn't give me any useful information on the change in flow per change in pressure. This is a VERY standard item for pumps! Even told me that it was so application specific that they leave it to the distributors to provide this information.

My world of electronics has similar types of components. They're called voltage regulators (or current sources.) Everyone one clearly states the change in voltage various changes in load. They due this as its critical to the function of the circuit to know the regulators performance. Injecting chemicals into drinking water has the same requirements!

Contacted my distributor that in short said, I've been doing this for 20 years and I've never been asked this question! Of course, he couldn't tell me anything specific other than "it works in this application". Wow - I'm injecting potentiality hazardous chemical into our house water and I'm supposed to take his word in this? What testing have you done? What follow up have you done? Sorry dude this is a terribly pathetic answer - its my family that will be harmed.

I always find it interesting how when one ventures into the skilled trades field (and not having been formally trained in this area) - they seem to think you're an idiot when you do something outside the normal process.

As my original experiment was crude (a "chicken test" - poor chickens) - I performed a better one. Basically measured the amount of water removed from my bucket after injecting the water into a tube a various pressures for a known time.

10 psi - 2.96 oz/min
15 psi - 2.95 oz/min
20 psi - 2.8 oz / min
25 psi - 2.7 oz / min
60 psi - 2.3 oz / min

There's a 25% difference!

Fortunately for me - the distributor will take it back. But I'll be out shipping two ways.

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