Ultrasonic Flowmeter (FH8300)

You must to calibrate analogue output

Contact the manufacturer for advice. Without seeing the wiring diagram as installed, it is difficult to suggest anything else.

I agree with the previous responder that stated that one must calibrate the analog output but also the DCS input needs to be re-calibrated by some reprogramming of the DCS.

With all ultrasonic flowmeters, one must ensure that the system parameters are entered correctly (fluid parameters like fluid temperature, specific gravity or in some flowmeters the actual liquid being measured, pipe parameters like pipe diameter,pipe material and pipe wall thickness). Incorrect entered pipe parameters can cause incorrect readings due to a phenomenon called beam scattering, in which the sent ultrasonic signal will travel around the outside of the pipe vice through the pipe wall through the fluid and through the other side. Because the flowmeter scales its output power in accordance with the entered pipe and fluid parameters, there is not sufficient emitted power to go through the pipe wall at both ends. To minimize this we used duct tape along the sides of the output transducer, from the back to approximately 4 inches forward in the direction of beam travel (same as flow direction). If the transducers are mounted in reflect mode and the distance is short enough (small diameter pipe), then the tape is mounted along the sides of the transducers from the back of the emitter to the back of the reciever. This method is especially helpful when non-standard pipe wall thicknesses are inuse.

Also check to see that the transducers are mounted correctly, either in direct mode or reflect mode. If there is a small amount of misalignment, this will cause incorrect readings or none at all. Most ultrasonic flow meters come with mounting brackets (Siemens/Controlotron do, I am not familiar with others) that will make it easy to mount and calibrate. Also, ensure there is sufficient coupling compound, either too little or too much can affect the reading.

The above information I have gotten from my own experiences with ultrasonic flowmeters and I am glad to pass this on.

Good luck

If your calculated calibrated max flow is 36.415 m3/hr, then the DCS side is indicating correctly, and the output from the meter needs to be calibrated for proper zero and span.The LCD display may be malfunctioning if it indicates zero flow with a milliamp input, or input polarity may be reversed.Check connections to input resistor of LCD display for good continuity.

It is advisable to start from the beginning and calibrate all indicators from scratch, using an accurate milliamp source,and finalizing with the meter output itself.This way, all outputs will agree with each other.

Confucious say:Man with two watches never know exactly what time it is.