A valve is a device used in a fluid system to control the direction, pressure, and flow rate of the fluid. It is a device that enables the flow or cessation of the medium (liquid, gas, powder) in the piping and equipment, and can control its flow rate.
A valve is a control component in a pipeline fluid transportation system, used to change the channel cross-section and medium flow direction, and has functions such as diversion, cut-off, throttling, check, diversion, or overflow pressure relief. Valves used for fluid control range from the simplest globe valve to various valves used in extremely complex automatic control systems, with a wide variety of varieties and specifications. The nominal diameter of valves ranges from extremely small instrument valves to industrial pipeline valves with a diameter of up to 10m. It can be used to control the flow of various types of fluids such as water, steam, oil, gas, mud, various corrosive media, liquid metals, and radioactive fluids. The working pressure of the valve can range from 0.0013MPa to 1000MPa at ultra-high pressure, and the working temperature can range from ultra-low temperature of c-270 ℃ to high temperature of 1430 ℃.
The control of valves can adopt various transmission methods, such as manual, electric, hydraulic, pneumatic, turbine, electromagnetic, electromagnetic hydraulic, electro-hydraulic, pneumatic, spur gear, bevel gear drive, etc; Under the action of pressure, temperature, or other forms of sensing signals, the valve can act according to predetermined requirements, or simply open or close without relying on the sensing signal. The valve relies on driving or automatic mechanisms to make the opening and closing parts move up and down, slide, swing or rotate, thereby changing the size of its flow channel area to achieve its control function.
1. Electromagnetic valve
Electromagnetic valve is an industrial equipment controlled by electromagnetism, which is an automation basic component used to control fluids. It belongs to the actuator and is not limited to hydraulic or pneumatic systems. It is used in industrial control system to adjust the direction, flow, speed and other parameters of medium. The solenoid valve can be combined with different circuits to achieve the expected control, and the accuracy and flexibility of the control can be guaranteed. There are many types of solenoid valves, and different solenoid valves play a role in different positions of the control system. The most commonly used ones are one-way valves, safety valves, directional control valves, speed regulating valves, etc.
The thermal expansion valve controls the flow rate of refrigerant entering the evaporator by controlling the degree of overheating of the gaseous refrigerant at the outlet of the evaporator. The thermal expansion valve achieves throttling from condensation pressure to evaporation pressure, while controlling the flow rate of refrigerant; Although its size is small, its function is enormous. Its performance directly determines the quality of the entire system. It provides the evaporator with liquid in the best way to ensure stable superheat of the refrigerant vapor at the outlet of the evaporator. The temperature sensing bulb must have good contact with the suction pipe of the compressor to accurately sense the suction temperature of the compressor, usually filled with the same refrigerant as inside the refrigeration system, Thus, the pressure feedback through the temperature sensor is the saturation pressure of this type of refrigerant corresponding to the suction temperature of the compressor. The expansion valve ensures the optimal and optimal liquid supply method of the evaporator when the operating environment changes (such as changes in thermal load). The filling amount of the temperature sensor is only corrected based on the complete evaporation of the liquid refrigerant in the temperature sensor at a specific temperature, This is equivalent to setting an upper limit for the pressure feedback from the temperature sensor above the expansion valve diaphragm, because if the surface temperature of the pipe wall continues to increase, it will only increase the temperature of the gaseous refrigerant inside the temperature sensor (in an overheated state), and the pressure will basically not change.
Electronic expansion valve is a throttling element that can enter the refrigerant flow rate of the refrigeration device according to a preset program. In situations where load changes are severe or operating conditions are wide, traditional throttling components (such as capillaries, thermal expansion valves, etc.) can no longer meet the requirements of comfort and energy conservation. The combination of electronic expansion valves and compressor variable capacity technology has been increasingly widely used. At present, research on electronic expansion valves generally includes three directions: application research, flow characteristics, control strategies, and algorithms.
As a new type of control component, electronic expansion valve has become an important link in the intelligence of refrigeration systems, and is also an important means and guarantee for the optimization of refrigeration systems. It is being applied in more and more fields. The application of electronic expansion valves will become increasingly mature with the progress and development of technology. In hot weather conditions, the advantage of electronic expansion valves is that they can better utilize the evaporator; In colder weather, it can reduce the operating pressure of the unit, thereby reducing power consumption and improving efficiency. The price of electronic expansion valves is twice that of traditional thermal expansion valves. There is a saying that "you get what you pay for". Electronic expansion valves are commonly used in high-end refrigeration equipment such as computer room air conditioning, precision air conditioning, and constant temperature and humidity air conditioning.
4. Ball valve
Ball valve refers to a valve that uses a ball with a circular through hole as the opening and closing component, and the ball rotates with the valve stem to achieve the opening and closing action. In the standard GB/T21465-2008 "Valve Terminology", it is defined as a valve whose opening and closing parts (balls) are driven by the valve stem and rotate around the axis of the square work ball valve. It can also be used for fluid regulation and control, among which the hard sealed V-shaped ball valve has a strong shear force between its V-shaped core and the metal valve seat welded with hard alloy, especially suitable for media containing fibers, small solid particles, and other materials. The multi way ball valve can not only flexibly control the convergence, diversion, and flow direction switching of the medium on the pipeline, but also close any channel to connect the other two channels. This type of valve should generally be installed horizontally in pipelines. Ball valve classification: pneumatic ball valve, electric ball valve, manual ball valve.
5. Check valve
Check valve, also known as one-way valve or check valve, is used to prevent the medium in the pipeline from flowing back. The bottom valve for water pump suction and closing also belongs to the check valve category. There are two types of body cover connection design for forged steel check valves: the first type is body cover bolt connection for forged steel check valves. Valves designed according to this connection form have the valve body and valve cover connected with bolts and sealed with spiral wound gaskets, which is convenient for maintenance; The second type of forged steel check valve with a fully welded and sealed body cover is designed according to this connection form. The valve body is connected to the valve cover with a screw, which is fully welded and sealed, with the advantage of no leakage.
In summary, different types of valves in the refrigeration and HVAC industry play an important role in controlling fluid flow and temperature regulation. Their diversity and widespread application enable refrigeration and HVAC systems to achieve precise temperature control, provide a comfortable indoor environment, and ensure efficient operation of the system. With the continuous innovation and development of technology, valves will play a more critical role in the field of refrigeration, heating and ventilation, bringing users a more intelligent, convenient, and reliable experience.
Hongsen Machinery provides you with comprehensive cooling solutions with its diverse product line. From electronic expansion valves, electric control valves, solenoid valves, thermal expansion valves to ball valves, safety valves, sight glasses, one-way valves, to shock resistant corrugated metal hoses, filters, YL oil flow switches, and pressure transmission accessories, each product is carefully designed to ensure efficient and reliable performance, bringing you cool and comfortable.