How is the output signal range of an intelligent valve positioner determined?

The output signal range of a valve positioner usually refers to the range of the air pressure signal used by the positioner to control the valve. When filling in the calibration record, it can be filled in according to the actual measured or set output pressure range. Yes, the maximum output range refers to the highest air pressure signal that the valve positioner can generate. Typically, this range is determined by the manufacturer or design parameters; for example, the air supply pressure corresponding to the common 4-20 mA control signal may be 0.2-1.0 MPa. When filling in the records, it is necessary to ensure that these data accurately reflect the actual operating status and parameters of the valve positioner. .

Personally, I think this isn’t very reasonable; it’s the conventional understanding. In actual testing, the pressure is far from that level, and the air supply pressure is not 1.0 Mpa either, so it’s impossible for the output pressure to reach 1.0 Mpa. According to data from various positioners, the output pressure is usually around 0–7 bar.

Your view is correct. Indeed, the output pressure range of valve positioners is usually relatively small, generally between 0 and 7 bar, depending on the specific model and application requirements. When filling out the calibration record, the output signal range should be specified based on the technical parameters of the specific device. If there are manufacturer manuals or technical specifications available for reference, these should be used to accurately fill in the actual range of the output signal. .

But there is still a question: if we use the actual range of 0–7 bar, it is well known that the valve cannot move when the output pressure of the actuator is very low. So is it appropriate to start the range at 0?

In practical applications, an output range starting from 0 may not accurately reflect the actual operating condition of the valve, as it might fail to function properly or respond slowly at very low pressures. Typically, a valve positioner has a minimum operating pressure or “starting pressure”; only when the pressure reaches this value can the valve begin to move. Therefore, when filling out the calibration record, it is more accurate to record the range from this starting pressure to the maximum output pressure, rather than starting from 0. This initial pressure value can be determined through testing to ensure that the records reflect the actual performance of the valve under real working conditions. If relevant information is provided in the valve positioner manual or technical documentation, those sources should also be consulted to determine and record the correct output signal range. Doing so will help to maintain and adjust the valve positioner more accurately, ensuring the reliable operation of the system. .