Rosemount 8712E Flowmeter Reading suddenly raising high and down

[hse112]

hi everyone,i am having a rosemount 8712e magnetic flowmeter (transmitter and sensor) , i installed them 3 months ago and suddenly the reading went crazy , sometimes it gets high and sometimes lower than the usual.
The Rosemount flowmeters are having a calibration code , it's inserted once when setting things up, so i'm wondering if there is a calibration process used for them instead of the calibration code, because iam not so sure that the calibration code is enough and i dont know whats the reason of the crazy reading and only after 3 months not years.
thanks in advance.

 

[gadfly56]

hi everyone,i am having a rosemount 8712e magnetic flowmeter (transmitter and sensor) , i installed them 3 months ago and suddenly the reading went crazy , sometimes it gets high and sometimes lower than the usual.
The Rosemount flowmeters are having a calibration code , it's inserted once when setting things up, so i'm wondering if there is a calibration process used for them instead of the calibration code, because iam not so sure that the calibration code is enough and i dont know whats the reason of the crazy reading and only after 3 months not years.
thanks in advance.

See here for the manual if you don't have a copy. See page 6-6 et seq for troubleshooting procedures.

 

[petersonra]

Is the piping system that the mag meter is installed in properly bonded and grounded? Meg meters don't like stray currents and the flowing liquids can easily create stray currents. Especially in plastic pipe line pipe or with high resistivity fluids

 

[JFletcher]

What kind of facility are these installed in? What is the application of the flowmeters? What kind of liquid is it measuring? Usual flow rate? What kind of pump do you have?

I ask because if the flowmeter is reading erroneously, it could be an actual flow problem rather than an error in the meter. That it has apparently been working fine for a few months and now suddenly gives odd readings, I'd check the process flow through other means.

Having worked WWTPs for years, most times when a flowmeter is throwing odd numbers, it's due to a process disruption (tank drained, cavitation of pump, pump ragged up, air in line, inconsistent pumping media, etc) rather than an error in the meter

 

[Saturn_Europa]

What type of fluid are you measuring?

It almost sounds like you are getting air in the pipe or that the electrodes are coated. I'd call the manufacturer and have their techs walk you through troubleshooting. Last time I called the call center it was located in the Philippines but their techs were fairly knowledgeable.

 

[JFletcher]

What type of fluid are you measuring?

It almost sounds like you are getting air in the pipe or that the electrodes are coated. I'd call the manufacturer and have their techs walk you through troubleshooting. Last time I called the call center it was located in the Philippines but their techs were fairly knowledgeable.

Ah, I was wondering if my fellow WWTP man would see this topic! Good morning!

 

[Saturn_Europa]

What kind of facility are these installed in? What is the application of the flowmeters? What kind of liquid is it measuring? Usual flow rate? What kind of pump do you have?

I ask because if the flowmeter is reading erroneously, it could be an actual flow problem rather than an error in the meter. That it has apparently been working fine for a few months and now suddenly gives odd readings, I'd check the process flow through other means.

Having worked WWTPs for years, most times when a flowmeter is throwing odd numbers, it's due to a process disruption (tank drained, cavitation of pump, pump ragged up, air in line, inconsistent pumping media, etc) rather than an error in the meter

You beat my post by 30 seconds

Excellent advice!!

 

[SonarMan]

+1 on the above. Most often I see that caused by pump cavitation/air bubbles in the flow...