Calibration of Controller

Hi! I am Aditya an Electronics & Instrumentation Engineer. I would like to know the calibration procedure of pneumatic controller? There are few instruments and specification are available to do this calibration. These are: two pens chart controller+recorder, 20 psi supply from an air regulator, a dial type pressure gauge, capillary tubes, another air pressure controlling valve or regulator, an U tube water manometer and other instruments as per requirement.

Now, please tell me how can I calibrate the controller o/p i.e. 3-15 psi pressure with respect to U-tube manometer and virtual inputs. Which is used to go actuator of the final control element.