1. The purpose of the selected valve, the working conditions and the control method.
2. the nature of the working medium: working pressure, working temperature, corrosion performance, whether it contains solid particles, whether the medium is toxic, whether it is flammable, explosive medium, the viscosity of the medium and so on.
3. the requirements of the valve fluid characteristics: flow resistance, discharge capacity, flow characteristics, sealing level and so on.
4. installation size and dimensions requirements: nominal diameter, connection with the pipe and connection size, size or weight restrictions.
5. Additional requirements for the reliability, service life and explosion-proof performance of the valve.
When selecting parameters, note that if the valve is to be used for control purposes, the following additional parameters must be determined: method of operation, maximum and minimum flow requirements, pressure drop for normal flow, pressure drop at shutdown, maximum and minimum inlet for valve pressure.
According to the above-mentioned basis and steps of selecting the valve, the internal structure of each type of valve must be well understood in order to properly and correctly select the valve, so that the correct choice can be made for the preferred valve.