Section 232.309 - Equipment and devices used to perform single car air brake tests(a) Equipment and devices used to perform single car air brake tests shall be tested for correct operation at least once each calendar day of use.(b) Except for single car test devices, mechanical test devices such as pressure gauges, flow meters, orifices, etc. shall be calibrated once every 92 days.(c) Electronic test devices shall be calibrated at least once every 365 days.(d) Test equipment and single car test devices placed in service shall be tagged or labeled with the date its next calibration is due.(e) Each single car test device shall be tested not less frequently than every 92 days after being placed in service and may not continue in service if more than one year has passed since its last 92-day test.(f) Each single car test device shall be disassembled and cleaned not less frequently than every 365 days after being placed in service. 66 FR 4193 , Jan. 17, 2001, as amended at 66 FR 39689 , Aug. 1, 2001