Flowmeter Issues with PD Pump
Flowmeter Issues with PD Pump
(OP)
Hi Everyone,
We are having issues at our facility with a mag meter and a metering pump. The pump is an electric diaphragm pump with adjustable stroke length used for metering ferric sulfate into a tank.
The problem is that we aren't getting accurate readings from the flowmeter because the flow isn't constant. The stroke length is backed off as much as it can be but it doesn't solve the problem. Ideally I could get a smaller pump.........but I thought I would ask some smart people if there is a fix in mind :)
The flowmeter is installed in the vertical position.......
Thanks!!
PR
We are having issues at our facility with a mag meter and a metering pump. The pump is an electric diaphragm pump with adjustable stroke length used for metering ferric sulfate into a tank.
The problem is that we aren't getting accurate readings from the flowmeter because the flow isn't constant. The stroke length is backed off as much as it can be but it doesn't solve the problem. Ideally I could get a smaller pump.........but I thought I would ask some smart people if there is a fix in mind :)
The flowmeter is installed in the vertical position.......
Thanks!!
PR





RE: Flowmeter Issues with PD Pump
David
RE: Flowmeter Issues with PD Pump
RE: Flowmeter Issues with PD Pump
RE: Flowmeter Issues with PD Pump
RE: Flowmeter Issues with PD Pump
What is the stroke rate of your metering pump? How many strokes per minute (approx.)? The pulse flow characteristic increases with low stroke rates.
A pulsation dampener might be a solution, too. But that only makes sense if pressure and flow are high.
RE: Flowmeter Issues with PD Pump
This pattern of flow is likely to cause excessive wear and ultimate failure of the meter.
For the most part today we need to look to the flowmeter electronics which are generally much more sophisticated than previously but which may trade off the primary element response time for a longer update time in the electronics.
Then too some meters are inherently slow responding, but not turbine meters.
Turbine meters are actually very fast responding, something like 5-7msec to 95% of a step change in flow and it is why they are used in jet engine test rigs where they require the meter to be able to handle the SNAP tests and turbines were originally used for rocket applications being able to handle the high G forces and high vibration environments.
JMW
www.ViscoAnalyser.com
RE: Flowmeter Issues with PD Pump
RE: Flowmeter Issues with PD Pump
I would like to ask you to clarify me the below:
For most Mag meters manufacturers they type ( medium control: separate electrode???) what they mean by that??
Thanking you
Ramy
RE: Flowmeter Issues with PD Pump
RE: Flowmeter Issues with PD Pump
RE: Flowmeter Issues with PD Pump
RE: Flowmeter Issues with PD Pump
http://www.youtube.com/watch?v=f949gpKdCI4
RE: Flowmeter Issues with PD Pump
However, a pulsation dampener will probably not completely fix the problem.
You should consider adding a totalizer to the flowmeter output. The flowmeter will accurately measure the total flow, it will just not display the average flow over time.
If you totalize the flow over a set time period, you can calculate the average flow over that time.
RE: Flowmeter Issues with PD Pump
A properly sized and selected pulse dampener will solve the problem completely. If the flow accuracy really matters, verify this with a calibration column on the suction side.
If you had a higher discharge pressure, you'd have check valve efficiency to worry about as well. Think about it: one of the reasons that real PD pumps deliver less volume per stroke as the discharge pressure increases is due to check valve leakage, which implies reversing flow in the discharge line. Without a proper pulse dampener, you're asking a lot of any type of flowmeter to give you an accurate measurement of the net forward flow for a stream which changes direction every stroke.
RE: Flowmeter Issues with PD Pump
Moltonmetal you are correct about the discharge pressure. The pump is connected to a large atmospheric tank. I was contemplating throttling the discharge to see if this had any impact.
RE: Flowmeter Issues with PD Pump