Testing System Provides On-site Verification of Magnetic Flowmeters

Krohne Co. recently introduced MagCheck, a new portable testing and verification device for its electromagnetic flowmeters. The device allows operators to check functionality and accuracy of a flowmeter without taking the meter out of the pipeline or interrupting the process.

The testing system was developed based on demands from the wastewater industry and complies with regulatory requirements that demand periodic verification of flowmeter performance. When combined with available PC software, MagCheck can be used as a compliance tool that verifies performance while creating an archived calibration record that is accurate to within 1 percent of the original factory calibration.

The MagCheck device is designed for testing Krohne's flowmeters in the field. No batteries or other power sources are needed. It connects on-site via plug and play connections without interrupting the flow and without removing the flowmeter from the pipeline or removing the converter-electronics.

The system's PC software is compatible with Windows 95, 98 or NT 4 or 2000. The system enables trend analysis with meter history, drift and error identification. It establishes verification certificates stating meter performance versus original factory calibration.

MagCheck uses available line power at the flow tube and can be used with most Krohne flowmeter converters. It can be employed either as an automatic verification instrument or as a manual flow signal calibrator, depending on the converter type.

The standard MagCheck product is supplied in a kit and includes a suitcase, connection cables for IFC 010, IFC 020, IFC 090, IFC 110 converters and an RS 232-cable for download of verification data to a PC. The kit includes an AC power supply adaptor plus a CD-ROM with MagCheck PC-software and a manual.

In automatic mode, MagCheck performs a test run during which all converter data are read, the essential parameters are measured and the results are stored. No additional instruments (laptop, printer, etc.) are needed during the on-site verification of the flowmeter.

The following parameters are tested during the verification:

Primary head:
• Electrode resistance
• Isolation resistance of the field coils
• Resistance of field coils

Converter:
• Field current and frequency
• Primary signal processing (Signal Input Instrumentation Amplifier, Analogue/Digital-conversion) at 25%, 50%, 75%, 100% of full scale value
• Active current output at factory calibration points
• Pulse output at 50% of full scale value

The device can also serve as an accurate flow signal calibrator for older Krohne converters. Unlike its predecessor, with MagCheck operators do not need a calculator, an ammeter or a pulse counter. Operators just enter full scale, meter size, GK and are ready to input any flow value (with a resolution of 0.1%). MagCheck gives an accurate display of zero point, current output, frequency output and field current.

With manual verification of Krohne flowmeter converters, the following parameters are tested:

Signal converter:
• Field current and field frequency
• At selectable flow values (0...>100% of the entered full scale value, in steps of 0.1%)
• Primary signal processing (Amplifier, Analogue/Digital-conversion)
• Current output
• Pulse output