If it is a low range transmitter, then precision pneumatic test equipment like “Wallace and Tiernier” and pneumatic pump (or air supply) may be used.
If it is a high range transmitter, then a hydraulic pump and a test gauge are to be used.
Yokogawa CA700 Pressure Calibrator has a basic accuracy of 0.01% of reading on pressure measurement and 0.015% of reading on Current/Voltage source/measurement, which makes it the most accurate calibrator in the portable calibrator class.
A calibrated fluke and a calibrated pressure gage on a hand pump.