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Join Date: Mar 2011
Location: Lubbock, Texas
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Mag flow meter (Signet) totalizer creep

03/16/2017 12:00 PM

Have been witnessing that our mag flow meter on raw water to media filter is steadily creeping up in totalizer reading on a daily basis, although we have not operated system.

At first, I thought valve leak by, but in the plant area (RO systems) the drains are completely dry where concentrate or discarded permeate during rinse in leaves the system. Unfortunately, the meter is located on a 4" diameter vertical pipe run leading to media filter inlet (common header to "A" vessel and "B" vessel).

I believe what I am witnessing to be the meter detecting thermal currents of water in the pipe that is (and appears to be) static as to bulk flow velocity.

Any suggestions how to eliminate this pesky error to our measurement?

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#1

Re: Mag flow meter (Signet) totalizer creep

03/16/2017 3:17 PM

Not sure what model you have, but most mag flow meters have a setting for "low flow cutoff":

Low Flow Cutoff: Set a flow rate that the 2551 Magmeter will use as a minimum threshhold.

If the flow rate falls below this value, the 2551 will respond as if the flow were zero.

That should stop the totalizer creeping issue.

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#2
In reply to #1

Re: Mag flow meter (Signet) totalizer creep

03/16/2017 4:30 PM

Thanks. It is a Signet make, but I will research what to do with it from here.

It is reassuring that I have not totally gone bonkers.

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#3
In reply to #2

Re: Mag flow meter (Signet) totalizer creep

03/17/2017 8:54 AM

Actually, that is a pretty common problem. I usually do all the totalizing in the PLC, where I can "blank" the signal based on pumps running, valve open...

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#4
In reply to #3

Re: Mag flow meter (Signet) totalizer creep

03/17/2017 10:31 AM

Yeah, we also probably have a limit set correctly in the PLC (4-20 signal), it is just that I record daily totalizers directly off the XMTRs.

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