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Join Date: Jul 2010
Posts: 75

Level Transmitter Use as Flow Measurement

04/27/2012 11:00 PM

I've got a level transmitter in a syrup tank which controls' the level whereby opening the discharge valve when the level is high....closing when the level is low. at the output going to another process, the syrup is injected by a phosporic and flocullant dosing pumps in (ppm). my question is, can i use the level control of the syrup tank for the output dosing instead of the flowmeter?

thanks

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#1

Re: level transmitter use as flow measurement

04/27/2012 11:16 PM

Yes, if the flow never changes.

If the flow changes, use a flow meter.

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#7
In reply to #1

Re: level transmitter use as flow measurement

04/29/2012 10:06 PM

I bow to the master. Who would have thought engineering was comedy fodder. Game on...

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#8
In reply to #7

Re: level transmitter use as flow measurement

04/29/2012 10:24 PM

All the world's a stage.

Game off...

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#9
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Re: level transmitter use as flow measurement

04/29/2012 10:31 PM

Understood No. Enjoy your stage. Good by.

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#2

Re: level transmitter use as flow measurement

04/27/2012 11:26 PM

The description of your system is cryptic at best. However, in principle, it should be possible to control flow as change in level, similar to loss-in-weight solids feeders do, with the same inherent limitations.

Sounds like you already have a flowmeter. Why do you not want to use it?

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#5
In reply to #2

Re: level transmitter use as flow measurement

04/29/2012 8:44 PM

i don't have one thats why this question. will use it for the ratio/proportion for the chemical dosing of the 2 pumps.

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#6
In reply to #5

Re: level transmitter use as flow measurement

04/29/2012 9:06 PM

Sounds like you want to dose syrup with phosphoric acid and flocculant as it's being pumped from a tank to ?.

If you expect real, useful assistance, please attach a flow diagram sketch with complete data on all pumps involved, flow rates, and size of syrup tank. What are the characteristics of this 'syrup'?

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#10
In reply to #5

Re: level transmitter use as flow measurement

04/30/2012 4:25 AM

It is not possible to do meaningful flow-paced dosing without having a flowmeter on the output of which the dosing flow is to be based.

#1↑ is √.

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#3

Re: Level Transmitter Use as Flow Measurement

04/29/2012 1:56 AM

Yes, We can use it with out flow meter.

Using flow meter is advisable cause of reliability.

Now the Level Transmitter O/P will be directly proportional to the input of the second tank.

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#4

Re: Level Transmitter Use as Flow Measurement

04/29/2012 12:15 PM

No. Still no. If 'syrup' = food for human consumption & maybe some quality standards in terms of 'recipe', you'd be best advised to tread carefully. Heck, I like my cat too - you're not 'dosing' him (inaccurately), are you?

That said, if 'dosing pumps' are solenoid metering pumps e.g. LMI, they are calibrate-able and repeatable within a certain range of stroke & frequency. This assumes the check valves, foot valve, diaphragm, tubing, etc. didn't / doesn't get gunked up (yeah, right). If you don't change stroke, output can be an implied function of frequency, controlled and measured by analog input to the pump. Flowmeters @ such low rates - good luck (some of them are just frequency counters, anyway). There are no-flow switches for alarm purposes which sort of work.

To try to answer your question before I get tired - dosing pumps are very small displacement things (at least for the purposes of this conversation) - even a 55 gallon drum liquid level isn't gonna change fast enough to have any sort of reasonable PV change to implement a control loop. Your results may vary. Your circumstances may be different.

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#11
In reply to #4

Re: Level Transmitter Use as Flow Measurement

05/25/2012 3:23 AM

thank you all contributors.....much appreciated

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