How to maintain and upkeep MAC solenoid valves
MAC solenoid valves are mainly installed on thermal power units to provide protection for large pumps and prevent water backflow. The air discharge check valve works in conjunction with the small flow automatic recirculation bypass valve of the water pump. When the feedwater pump is in low load or the outlet shut-off valve is closed, the automatic recirculation bypass valve (automatic recirculation valve) should be in the open position to ensure the safe operation of the water pump. When the air discharge check valve is opened, the recirculation bypass valve automatically closes. Not suitable for media containing solid particles and high viscosity. This valve works in conjunction with the recirculation bypass valve to maintain the safe operation of the system.
The working principle of MAC solenoid valve: Automatic recirculation valve is designed to meet the needs. For centrifugal pumps, a bypass is required to prevent overload and overheating vaporization that may cause damage to the pump when operating below the specified low flow rate. The water output varies with the boiler load. When starting or when the load is very low, the feedwater pump is likely to operate with a small or zero feedwater volume. The water in the pump body is heated by the friction of the impeller for a long time, causing the water temperature to rise. After the water temperature rises to a certain degree, vaporization occurs, forming cavitation. Causing damage to the water supply pump.
To prevent the occurrence of the above phenomenon, a recirculation system is installed between the outlet of the feedwater pump and the deaerator (or condenser) water tank. The recirculation system can be opened when the feedwater pump is just started or when the feedwater volume is small to a certain extent. Return a portion of the water to the deaerator tank and pass it through the water pump with a certain amount of water (usually about 30% of the rated flow) without causing the water temperature in the pump to rise and vaporize. And when the water supply is under normal conditions, close the recirculation system. The previous control method consisted of a complex control system that formed the pump's protection and control system. The recirculation system consists of a small flow valve, a check valve, and a flow measurement system. The flow measurement system in the system determines when to turn on or off the recirculation system.
The MAC solenoid valve is in the open position for safe operation of the water pump. When the air discharge check valve is opened, the recirculation bypass valve automatically closes. Not suitable for media containing solid particles and high viscosity.
The MAC solenoid valve works in conjunction with the recirculation bypass valve to maintain the safe operation of the system.
Introduce the structural characteristics of MAC solenoid valve to you:
1. When the main valve disc moves up and down and the medium flows back, the channel is closed under the pressure of the medium and the action of the spring. At this time, the bypass valve opens. When the main valve disc is fully opened, the bypass valve closes.
2. The valve disc seal is made of stainless steel overlay welding, which has strong wear resistance, abrasion resistance, and reliable sealing.
3. Valves should be installed vertically.
MAC solenoid valves can also be used on pipelines to supply auxiliary systems where the pressure may rise above the main system pressure.
Automatic recirculation valve, also known as pump protection valve or small flow valve, is used for automatic recirculation of small flow in centrifugal pumps to prevent overheating and noise under low load
The valves can be neatly placed on the floor of the warehouse. Ensure that the flange connection surface is not grounded. Protect the valves of the power plant from damage.
For power plant valves that will not be used in the short term, asbestos packing must be removed to prevent electrochemical corrosion and valve stem damage.
Check the valves of the power plant in the warehouse. If rainwater or dust enters, please wipe them clean and store them.
The inlet and outlet of power plant valves must be sealed with wax paper or plastic plates to prevent dust from entering.
The treated surface of power plant valves may rust in the atmosphere, so they must be coated with anti rust oil and protected.
Valves installed in outdoor power plants must be covered with rain and dust resistant components, such as felt and waterproof tarpaulin. The warehouse storing power plant valves must be kept clean and dry.
2、 Usage and maintenance
The use and maintenance are aimed at extending the lifespan of valves in power plants and ensuring reliable opening and closing. Dry threads often rub against valve stem nuts and require a small amount of butter or graphite powder for lubrication.
For power plant valves that are not frequently opened and closed, please rotate the handwheel regularly to add grease to the valve stem threads to prevent jamming.
Outdoor power station valves. A protective layer should be added to the valve stem to prevent rain, snow, dust, and rust.
If the valve is a mechanical transmission device, it is necessary to add lubricant to the gearbox in a timely manner to keep the valve clean.