Function and Classification of Self-operated Regulating Valve
1 Function of Self-operated Regulating Valve
Self-operated control valves use the feedback signals (pressure, differential pressure, temperature) from the output end of the valve to transmit to the actuator to drive the valve disc to change the opening of the valve, so as to achieve the purpose of regulating pressure, flow and temperature.
2. Advantages of Self-operated Regulating Valve
Self-operated regulating valve is a new type of self-operated regulating valve. Compared with manual control valve, it has the advantage of automatic regulation; compared with electric control valve, its advantage is that it does not need external power. The application practice has proved that in the closed water circulation system (such as hot water heating system, air conditioning chilled water system), the correct use of this valve can easily realize the flow distribution of the system, realize the dynamic balance of the system, greatly simplify the commissioning work of the system, and stabilize the working state of the pump, etc.
Classification of 3 self-operated control valves
Self-operated control valves are divided into direct and indirect action.
Direct Acting Regulating Valve
Direct-acting regulating valve is also called spring-loaded regulating valve. It has elastic elements in its structure, such as spring, bellows, bellows, thermostats, etc. It uses the principle of balance of elastic force and feedback signal.
Indirect Acting Regulating Valve
The indirect action type control valve adds a commander (pilot valve) to amplify the feedback signal and then drives the main valve disc movement through the actuator to change the valve opening.
If it is a pressure regulating valve, the feedback signal is the outlet pressure of the valve, which is introduced into the actuator through the signal tube.
If it is a flow control valve, there is an orifice plate (or other resistance device) at the outlet of the valve. The differential pressure signal is taken out from both ends of the orifice plate and introduced into the actuator.
If it is a temperature regulating valve, the outlet of the valve has a temperature sensor (or a temperature bag) driving the actuator through the thermal expansion and contraction of the medium in the temperature sensor.
Characteristic of 4 Self-operated Regulating Valve
Self-operated regulating valve does not need additional energy, and can work in an electric and gas-free place, which is convenient and energy-saving. The pressure subsection range is fine and cross each other, and the adjustment precision is high. Pressure setting values can be set continuously during operation. The ratio of pre-valve pressure to post-valve pressure can be 10:1-10:8 for the regulation of post-valve pressure. Rubber diaphragm type detection, high accuracy of the actuator, sensitive action. Pressure balancing mechanism is adopted to make the control valve sensitive and accurate.