How important is it to periodically have the Pile Driving Analyzer® (PDA) sensors recalibrated?
Pile Dynamics, Inc. (PDI) recognizes that generally both acceleration and strain transducers are stable and unlikely to change calibration within the specified tolerance of +/- 2 %. You may evaluate this by comparing the velocity (times impedance) with the force at the early impact times; if there is good proportionality between the two, then it is likely that both strain and acceleration are properly calibrated. However, the calibration process may identify a defective sensor. It is therefore important to have sensors periodically checked by PDI or one of its authorized agents, to ensure that they are performing according to specifications.
In accordance with American Society for Testing and Materials (ASTM) D4945 recommendation, Pile Dynamics recommends that all sensors be recalibrated every two years, regardless of how much they have been used during this period. If any sensor gives questionable data prior to two years, Pile Dynamics also recommends recalibration.
It should be noted that Pile Dynamics has a policy of recalibrating any sensor that is returned to its Maintenance Department for check-up or repair.