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　　After pressure source connected to each other through hoses and fittings made of, balance valve closed and sealed gas path inspection of the case, then the ammeter (voltmeter), Communicator access to the transmitter output circuit, power preheating start calibration. We know no matter what type differential pressure transmitter, its positive and negative pressure chamber has a vent and drain valves or cocks; this provides a convenient on-site calibration of differential pressure transmitter for us is to say, without removing guide pressure pipe will be able to calibrate differential pressure transmitter. Differential pressure transmitter calibration when the first positive and negative valve three valves closed, open balancing valve, and then loosen the exhaust vent or drain cock valve, fitting in place after using homemade pick exhaust plenum , drain valves or cocks; and a negative pressure chamber to maintain a loosened state, making it through the atmosphere.
　　Calibration conventional differential pressure transmitter
　　First state damping to zero, zero adjustment first, then add full scale pressure span adjustment, so that the output is 20mA, the adjustment at the scene talking about the fast, in this introduction zero and span of rapid adjustment method. Almost zero when adjusted for full-scale impact, but when adjusted for full-scale zero impact when not migrate with their impact is about 1/5 of the amount of the adjustment range, that range upward adjustment 1mA, Zero will move up to about 0.2mA ,vice versa.
　　Smart Pressure Transmitter Calibration
　　By conventional methods described above for smart transmitter calibration does not work, because this is the principle by the HART transmitter structure decision. Because smart transmitter between 4-20mA current signal input and generating a pressure source, in addition to mechanical, circuit, there are micro-processing chip input data computing tasks. Therefore, the conventional method adjustment differ.
　　In fact, manufacturers of smart transmitter calibration is also described, such as ABB transmitters, calibration there: "Setting the Range" and "the quantitative procedure", "fine tuning" of the points. The "set range" operating mainly through LRV.URV digital settings to complete the configuration, while the "ration procedure" operation requires the transmitter connected to a standard pressure source, through a series of guided instruction by the change Get directly sensing the actual pressure and set values. The initial range ultimately set depends directly on the real pressure input value. But to see that although the transmitter output analog input value relationships with and correct, but the value of the process value display digital readout will be slightly different, which can be calibrated by the spinner. Since each part individually adjust both the FBI and will need, so when the actual calibration Proceed as follows:,
　　1, 4-20mA do first trimming, the interior of the transmitter to the correction D / A converter, since it does not involve the sensing means, no external pressure source.
　　2, the entire fine-tuning to do it again, so 4-20mA, pressure readings and the actual signal applied to the digital phase consistent, requiring a pressure source.
　　3, the last to do heavy weight process, by adjusting the analog output 4-20mA with external pressure source coincide Zero (Z) and the effect on its transmitter housing, adjusting range (R) as a switch identical .