Is there such a thing as pressure before and after the cut-off valve?

There is no such thing as pressure before and after a cut-off valve. Operating pressure may refer to the air source pressure.

A shut-off valve, also known as a stop valve or isolation valve, serves primarily to open or close the flow of fluid, thereby preventing the passage of the medium. Cut-off valves indeed involve the concept of pressures before and after the valve; here, “before the valve” refers to the pressure on the inlet side of the valve, while “after the valve” refers to the pressure on the outlet side of the valve. In a fluid system, when a valve is closed, the pressure before the valve is usually higher than the pressure behind it. This pressure difference is one of the key factors that enable the valve to close successfully and prevent fluid flow. When designing and testing cut-off valves, the maximum operating pressure they are capable of withstanding is taken into account, that is, the maximum pressure upstream of the valve, in order to ensure the valve’s performance and sealing characteristics under such pressure conditions. The operating pressure listed in the data table you mentioned generally refers to the pressure range within which a valve can operate safely. This operating pressure should be understood as the pressure at which the valve can open or close properly while maintaining a seal and preventing leaks. If there are further technical specifications and requirements, it is recommended to consult the specific product manual or contact the manufacturer to obtain detailed information on this cut-off valve, including the maximum operating pressure (pressure before the valve), test pressure, etc., as well as any special usage or installation requirements. .

When the cut-off valve is in the open position, the pressure difference before and after it is merely the pressure drop across the valve. When in the closed state, the pressure at the valve inlet is higher than the pressure at the outlet.

No, the pressure listed in the data table is the operating pressure of the pipeline in question

For cut-off valves, the maximum closing pressure difference is determined by considering the pressure before the valve and the pressure after it. (All scenarios must be considered regarding the pressure difference before and after the valve; in some batch reactions, the pressure behind the valve can sometimes be higher than that in front of it, so attention should also be paid to the reverse pressure difference.) Then select the actuator.

For cut-off valves, the pressure difference before and after the valve must be taken into consideration, and an appropriate actuator should be selected. Operating pressure refers to the operating pressure of the process.