In the following cases, we can consider Upper mounting positioner:
1. When there is no spring or piston actuator to realize proportional action;
2. When the diameter of regulating valve is relatively large (DN>100);
3. For Split range control;
4. When it is necessary to increase the action speed of the regulating valve;
5. Using High temperature or low temperature control valve;
6. When the inflow medium pressure and pressure difference are large;
7. When the valve is to be reversed (air to close and air to open switch each other);
8、 When electric signals are used to control the pneumatic actuator.
9、 When operating the actuator of non-standard spring with standard signal (spring range beyond 20~100KPa);
10、 When the flow characteristic of the valve needs to be changed (the positioner cam can be changed).
The above are all kinds of situations that the valve needs to use the positioner, and I hope it will be helpful to everyone.
