How to calculate the pressure before and after a valve
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Vacuum distillation tower (-0.09 MPa): 1. Forced extraction is carried out from the tower bottom using a pump; the pressure at the pump outlet is 0.45 MPa (the pump is located on the first floor), while the extraction control valve is on the third floor. The vertical distance between the two is approximately 15 m； The vertical distance between the production control valve and the production horizontal pipe, relative to the control valve, is about 3 meters. How can the pressures on the valves before and after the control valve be calculated? 2. The reflux tank is on the 6th floor, while the production control valve is on the 3rd floor; the vertical distance between them is 15 meters. Production takes place using natural gravity (not forced reflux) ； The vertical distance between the production control valve and the production horizontal pipe, relative to the control valve, is about 3 meters. How can the pressures on the valves before and after the control valve be calculated?
The pressures before and after the control valve are conditions provided by the process to the instruments, and they serve as important parameters for selecting the control valve. The pressure before the valve is usually the outlet pressure of the pump, as control valves are typically installed not far from the pump outlet. If the distance is relatively large, calculate the pressure drop from the pump outlet to the control valve, and then the inlet pressure of the control valve can be determined. As for the outlet pressure, it is calculated by adding the pipe loss from the outlet pipeline to the equipment to the equipment pressure.
What impact does the pressure before and after the control valve have on the selection of pneumatic control valves? If extraction is done by gravity, what can the pressure difference before and after the valve generally be? (The medium is considered to be water.)
1. The resistance coefficient is calculated by reversing the Kv value provided by the valve manufacturer; the actual flow rate in the pipeline is measured, and then it is determined using Bernoulli’s equation and the law of conservation of mass.
Hello, if I knew the actual flow rate, I would install a control valve on the third floor while the pump is on the first floor. How can I calculate the pressures before and after the control valve? Install the control valve horizontally. Thank you. In technical renovation projects, I often encounter the need to install control valves; it is necessary to calculate the closing pressure difference of these valves, as well as the pressures before and after the valve, and then provide these process conditions to the instrumentation team so that they can select the appropriate control valves.