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An electric control valve is a new type of control valve. Compared to manual control valves, it has the advantage of automatic adjustment; compared to electric regulators, it has the advantage of not requiring an external power source. The main control parameters for selecting electric control valves include: nominal diameter, design nominal pressure, allowable temperature range of the medium, flow coefficient, etc. Automatic control valves have many advantages, which is why they are increasingly favored by customers. However, to maximize the performance of these products, it is necessary to choose the appropriate control valve for each specific application. 1. For applications where a strict proportionality between flow rate and opening height is required, special control valves should be used. Ball valves and butterfly valves can generally be chosen for rough adjustment. 2. The sealing performance of a valve is one of the main indicators for evaluating its quality. The sealing performance of valves mainly includes two aspects: internal leakage and external leakage. Internal leakage refers to the degree of sealing of the medium between the valve seat and the closing element. Leakage refers to leakage in the valve stem packing area, leakage in the middle hole gasket area, and leakage in the valve body, all caused by casting defects. Leakage is not allowed. 3. The ideal flow characteristics of control valves include quick-open, parabolic, linear, and equal percentage types; it is necessary to select a control valve with the appropriate flow characteristic based on the actual operating flow requirements. 4. The nominal diameter of the control valve should be selected based on the flow rate required by the valve. The nominal diameter of the control valve should not be too large or too small. If the valve is too large, it will increase the project cost; when the valve is within a low percentage range, the adjustment accuracy decreases, resulting in poor control performance. If the valve is too small, the system resistance will increase, and even when the valve is fully open, the system still cannot meet the specified capacity requirements.