I can use the case of a pressure air meter.
When calibrating a pressure air meter we first test to verify the meter's appropriate initial pressure. We do this by filling the meter to the top with water (i.e. no air in the air meter), bringing the meter to the assumed initial pressure, and testing. If the meter reads 0% we have confirmed the initial pressure.
Then utilizing a calibrated vessel we remove a fixed volume of water representing 5% air. Once the water is removed we repressurize the air meter to the initial pressure we determined. We then test again. If we get a reading of 5% we than repeat at 10% air and so on.
If any of the readings are off by a certain amount we examine the meter, reconfirm the initial pressure, and start over.
On a regular basis we will utilize a "quick calibration" unit that we toss in the meter and fill with water. With the unit in the meter our tests should come up at 5% air. If it doesn't calibration needs to be reperformed.
In truth each device requiring calibration will typically have instructions specific to standard (i.e. ASTM, AASHTO, ACOE) it is being utilized to perform. If you're working with equipment for ASTM standards please check ASTM E329 and AASHTO R18 which include general details for Quality Control Management. Furthermore look at the individual test methods for calibration requirements.