At one time, we recommended regular recalibrations. Now we recommend recalibrations only for the following three conditions below.
Condition l: Your probe requires repair. After we repair your probe, we must recalibrate it.
Condition 2: You need the probe certified for your company’s quality program. In this case, we may not actually open the probe to make adjustments. First, we put the probe on our tilt table to generate a calibration form. Then, if the probe is found to be within tolerances, we print out the calibration form. However, if the probe is found to be out of tolerance, we open it, make the necessary adjustments, and then run the calibration test again.
Condition 3: If you follow ASTM Standard D7299 (http://www.astm.org/Standards/D7299.htm) and readings in the check stand or in an inclinometer installed on stable ground show drifting or unusual readings.
Summary: If your readings and graphs are consistent, and there is no obvious need for repair, we recommend that you continue using the probe as is. Recalibration is unlikely to significantly improve the performance of a probe that is already working well.
Note that the probe is a special case. Other instruments, particularly readouts, can benefit from annual recalibrations.