A more narrow definition of the term calibration simply involves comparing an instrument or measuring device to a standard, without making an adjustment to make the instrument read correctly. The second step, involving adjustment or “resetting the scale,” is sometimes called verification. In ordinary use, however, most people include the verification step in the standard process of calibration or re-calibration.

A company that pays $2,000 to have an ultrasonic flowmeter re-calibrated is most likely not going to be satisfied with a report that says, “We have tested your flowmeter against an approved standard and found that it is not reading properly.”  The customer probably already knew that, or they wouldn’t have pulled the flowmeter out of service for re-calibration. A company that pays to have a flowmeter calibrated expects it to come back reading correctly. This could involve replacing a piece of hardware, adjusting the K factor, making a software modification, or taking some other action to correct or “verify” the operation of the flowmeter.