Calibration and Maintenance 8.1 Calibrate the pressure-indicating device by means of a dead-weight tester of the piston type. If the device is a Bourdon-type gage, it must be calibrated while inclined at the same angle at which it is to be used. Preferably, calibrate with the gage in its normal position. For an instrument error of less than 3 %, calibrate the pressure-indicating device in such a manner that known pressures are applied dynamically at approximately the same rate as in testing of paper. Maximum reading pressure devices are subject to dynamic errors as well as ordinary static calibration errors. A suitable method of dynamic calibration for greater precision is described in Tuck et al. (2). 8.1.1 Calibrate gages in frequent use at least once a month. If a gage is accidentally used beyond its capacity, recalibrate before it is used again. 8.2 Calibration of Transducer/Readout SystemÐCalibrate the transducer can be calibrated on the same device as is used to calibrate gages. 8.2.1 Calibrate transducers in frequent use should be calibrated at least once a month.