Pressure difference
Differential pressure usually refers to the pressure difference between two points of the valve in the pipeline, such as the pressure difference between the front and back of the valve, the pressure difference between the two sides of the double flange, and so on.
It is not easy to calculate the pressure difference. The specific structure of the valve and the environmental pressure of the pipeline must be given, otherwise the calculation is impossible. The simple method is to install a pressure gauge and a flow rate meter at the water inlet and outlet ends of the valve, and directly read the pressure difference data.
Full pressure difference
When the valve is closed, there must be a pressure difference between the front end of the valve and the rear of the valve (the pressure difference is large at this time, called the full full pressure difference for short). The thrust generated by this pressure difference is added to the valve seat to create friction on the valve. Resistance torque, if you want to open the valve, you must use a reaction torque (manual or electric torque) to overcome it, this torque is called working torque. Of course, when the valve is opened, the resistance flowing through the valve is the pressure difference before and after the valve, which is much smaller than the full pressure difference.
