In Fan Coil Unit systems, solenoid valves and electric valves play a vital role. They are responsible for controlling the flow of refrigerant and regulating the flow in the pipeline, respectively, to ensure efficient and stable operation of the system. However, there are significant differences between the two in terms of working principles, application scenarios, and performance characteristics. A deep understanding of these differences will help to correctly select the appropriate valve and improve the overall efficiency and reliability of Fan Coil Unit systems.
Introduction and components of solenoid valve
Solenoid valves are valves that automatically control the flow of refrigerant in refrigeration systems. Solenoid valves can be divided into direct-acting and indirect-acting types. Solenoid valves used in commercial refrigeration equipment are generally direct-acting.
Solenoid valves consist of a valve body and a solenoid head. They are generally direct-acting. The so-called direct opening and closing solenoid valves use the armature in the solenoid head to directly control the opening and closing of the valve hole. The hole diameter is generally between 6-22mm.
Function and Working Principle of Solenoid Valve
The refrigeration system divides into high pressure and low pressure, liquid and gas. The solenoid valve protects the compressor from high-pressure liquid impact after stopping. Before the compressor starts, the system pressure balances. At this point, the solenoid valve powers on, starting the compressor. The refrigerant circulates and begins refrigeration.
When the compressor stops, the solenoid valve quickly powers off and cuts off flow. Refrigerant on the high-pressure side cannot return to the compressor in reverse. Instead, it flows through the compressor in the normal direction. Gradually, the refrigeration system balances with the compressor stop pressure.
Working Principle
Refrigeration equipment starts, and the electromagnetic coil generates force to open the valve. An energized coil and armature create an induced magnetic field. The armature moves the valve needle upward, opening the valve hole. Fluid then flows normally. Once the set temperature is reached, the coil de-energizes. The magnetic field disappears, and the armature falls due to spring force. The valve needle closes the valve hole, stopping fluid flow.
What is an electric valve
There are two types of electric valves. One is the angular stroke electric valve, which is used by the angular stroke electric actuator in conjunction with the angular stroke valve to realize the valve rotation within 90 degrees to control the flow of pipeline fluid; the other is the linear stroke electric valve: the linear stroke electric actuator is used in conjunction with the linear stroke valve to realize the up and down movement of the valve plate to control the flow of pipeline fluid. It is usually used in equipment with a high degree of automation.
Working principle of electric valve
The electric valve is usually connected by an electric actuator and a valve, and becomes an electric valve after installation and debugging. The electric valve uses electrical energy as power to connect the electric actuator to drive the valve to realize the opening and closing and regulating action of the valve. Thereby achieving the purpose of opening and closing or regulating the pipeline medium.
The driving device of the electric valve is a reversible electric motor, which drives the valve core to control the valve by rotating the motor for a certain period of time. It adopts AI analog signal control to adjust the flow of pipeline medium, and can also use digital signal control in specific pipeline environments.
Differences Between Electric Valves and Solenoid Valves
Application Scenarios
Solenoid valves open and close quickly with low power consumption. They provide excellent anti-leakage performance, making them ideal for corrosive, toxic, or chemical pipelines. In contrast, electric valves adjust pipeline flow effectively. They commonly appear at the outlet of air supply and refrigeration pipelines. They also work well in liquid systems like sewage treatment and beverage production.
Control Method
For on-off control, solenoid valves operate in two-position DO systems. They suit small pipelines, typically DN50 and below. Electric valves manage medium flow with AI control. They also handle large valves and air systems, offering greater versatility.
Functionality
Unlike electric valves, solenoid valves only offer on-off functions. These valves use coils for quick switching. Electric valves rely on motors, taking more time to open or close. However, they can control multiple flow states, such as open, closed, or partially open.
Flow Coefficient
The flow coefficient of solenoid valves is smaller. For example, a 25-caliber solenoid valve has a lower flow than a 15-caliber electric ball valve. Voltage shocks can easily damage solenoid coils. As simple switches, they perform basic opening and closing functions.
Power Source and Resistance
Electric valves, driven by motors, resist voltage shocks better. They handle large flows and pressures more effectively. While solenoid valves perform best in low-pressure systems, electric valves excel in larger and higher-pressure pipelines.
Cost and Special Requirements
Special process requirements often use solenoid valves, such as anti-leakage or specific fluid media. However, they are more expensive. Electric valves perform adjustment and switching functions, such as in fan coil unit systems. They are widely used across various industries.
