Section 90.203 - Certified person; maintenance and calibration(a) Approved sampling devices shall be maintained and calibrated by a certified person.(b) To be certified, a person shall complete the applicable MSHA course of instruction and pass the MSHA examination demonstrating competency in maintenance and calibration procedures for approved sampling devices. Necessary maintenance of the sampling head assembly of a CMDPSU, or the cyclone assembly of a CPDM, can be performed by persons certified in sampling or in maintenance and calibration.(c) To maintain certification, a person must pass the MSHA examination demonstrating competency in maintenance and calibration procedures every three years.(d) MSHA may revoke a person's certification for failing to properly carry out the required maintenance and calibration procedures.