Control valves are valves used to control conditions such as flow, pressure, temperature, and liquid level by fully or partially opening or closing in response to signals received from controllers that compare a "setpoint" to a "process variable" whose value is provided by sensors that monitor changes in such conditions. The opening or closing of control valves is usually done automatically by electrical, hydraulic or pneumatic actuators. Positioners are used to control the opening or closing of the actuator based on electric, or pneumatic signals. These control signals, traditionally based on 3-15psi (0.2-1.0bar), more common now are 4-20mA signals for industry, 0-10V for HVAC systems, and the introduction of "Smart" systems, HART, Fieldbus Foundation, and Profibus being the more common protocols.
A control valve consists of three main parts in which each part exist in several types and designs: Valve body, actuator, positioner.
The valves manufactured and sold by Shanghai Datian Valve Pipe Engineering Co., Ltd including self-control valve, manual valve, automatic valve, lining valve and fittings. Self-control valve are regulating valve, electric regulating valve, pneumatic valve, vertical pressure regulating valve, vertical temperature regulating valve, magnetic valve. The manual valves are gate valve, globe valve, ball valve, Butterfly valve, piston valve, plug valve, diaphragm valve and middle valve. Automatic valves are check valve, safety valve, pressure-reducing valve, water isolate valve, air vent valve, balance valve, breather valve, strainer and hydraulic valve. Lining valve are gate valve globe valve, ball valve, butterfly valve, diaphragm valve and lining pipe, elbow, template pipe and flange of all kinds of specification. Furthermore we can manufacture and process the specificial valve upon customer's request.
