A leading thermal mass flowmeter manufacturer, striving to contend with Sage Metering’s In-Situ Calibration Check, recently introduced the option to purchase an in-situ calibration verification system for one of their models. It should be no surprise that other manufacturers are striving to offer alternatives to Sage’s award-winning flowmeter which has set a new standard in gas mass measurement.
In “Leading the way for thermal flowmeter in-situ calibration” I shared the Sage Metering approach to in-situ calibration . Here I explain how perhaps the largest gas mass flowmeter manufacturer is offering onsite calibrations too. A key difference between this manufacturer’s approach and Sage Metering is that they are offering the option of buying the meter with a calibration verification system. Like any option, an added expense is associated with it, and it carries a hefty price tag of about $2,000 per meter in addition to the meter cost.
The manufacturer provides a calibration certificate with data from various pressure points and recommends the customer to repeat the calibration check at the same points to establish a baseline.
Their patented process involves installing a plumbing module near the meter which includes a check valve and sonic nozzle. To calibrate the thermal mass meter, a trained technician must loosen the locking collar and packing gland nut on the meter’s insertion probe, rotate it and lift the probe from the pipeline. Another module (pressure regulator and gauge kit) is set up near the meter to regulate a secondary gas source where a nitrogen bottle is connected. This module includes a pressure regulator and digital output. The regulated nitrogen flows to the plumbing module near the meter, where the check valve is opened and gas flows to the sensor. After a couple minutes, allowing for the electronic readings to stabilize, values are taken from the digital readout. This process is repeated at various pressure points which the factory used in their initial factory calibration. The data points should comply with the factory provided calibration data, and if they do, the process has verified the unit is accurate.
From an operations perspective, it would appear that a highly skilled technician would be required to install the calibration verification plumbing module, the regulator module as well as calibrate the meter using bottled nitrogen. Nevertheless, this company should be commended for this unique approach since the method does validate in-situ, that the thermal mass flow meter is accurate. The downside to this approach is that it is time consuming and expensive.
In my next post I share another gas mass flow meter manufacturer’s efforts at calibrating the unit on site.