What is the difference between calibration, re-calibration, and in-situ calibration verification? In this post, we define these and share the benefits of verifying that a thermal mass flow meter remains in calibration while still in the field.
What is calibration?
Once a manufacturer produces a meter, the meter must be calibrated before its sent to the end user.
From a simplistic perspective, calibration is checking a meter for correctness against a standard. For a thermal mass flow meter, the unit is reviewed or compared to a measurement taken at a specific rate(s) and data point(s); then compared to a known standard. The second step after calibration is resetting the scale, and most people associate this correction with calibration.
Sage Metering calibrates its thermal mass flow meters in its NIST Traceable calibration facility.
What is re-calibration?
After a meter has been in the field for some time, typically one year, most manufacturers recommend that the meter be returned to the factory (or a third party) for re-calibration. In this case, the meter is calibrated again and faces adjustments to guarantee accuracy.
Without using a calibrated instrument, there’s no confidence in the collected data. Why spend your company’s funds on a meter to measure gas flow if you’re not willing to ensure correct information? While this is a rhetorical question, I assure you that I have heard many people claim to waive a calibration because of the expense and inconvenience associated with it.
It is inconvenient and costly to recalibrate a meter.
Why is calibration such a problem for thermal mass flow measurement? Imagine buying a meter to measure gas at a remote location. There’s the expense of hiring a contractor or employee to install the unit. A year later, the company would need to hire another employee or contractor to return to the location, remove the meter and ship it back to the manufacturer (or some third-party lab). Then, of course, there’s the expense of hiring someone a couple of months later to reinstall the now-calibrated unit. Calibration, in this manner, is labor-intensive and costly.
What is in-situ calibration verification?
The Latin term in-situ means “in position.” In-situ calibration verification implies that a unit can be evaluated in position or on-site to determine if the meter remains in calibration from its original NIST calibration.
Benefits of On-site Calibration Verification
The obvious benefit, of course, is that the user does not have to deal with the inconvenience and expense of removing the meter from service and sending it to the manufacturer for annual calibration. If the user can verify that the meter retains its NIST calibration while in the field, it does not have errors that require adjustments, and there is no need to return the meter for re-calibration.
In addition to saving time and money, a meter that can perform frequent calibration checks now meets EPA GHG Reporting Rule and calibration requirements to measure GHG emissions. In other words, the ability to calibrate the thermal mass flow meter in the field opened new markets for thermal mass flow meters with the ability to verify that the meter remains in calibration.
More recently, new compliance regulations for monitoring emissions on engines and turbines require calibration verification.
Thermal Mass flow Meter In-Situ Calibration Pioneer
Sage Metering has led the way in introducing an in-situ calibration method for thermal mass flow meters. The Sage In-Situ Verification can occur without removing the meter from the pipe and without stopping the gas service. Sage was the first thermal mass flow meter manufacturer to introduce such a system. While many other manufacturers have followed and introduced their methods to compete, the Sage method remains the first, easiest, and quickest.
Read more about Sage Metering’s award-winning proprietary procedure and history.
Sage In-Situ Validation Procedure
Learn more about the onsite calibration verification here.