Manual regulating valves are essential terminal components for central air conditioning systems in industrial and civil buildings, used in ventilation, air conditioning, and air purification projects. They are typically installed in HVAC system ducts to control the airflow in branch pipes and can also be used for mixing fresh air and return air. Their main features include flexible operation, low noise, minimal leakage (enclosed type leakage <0.5%), a wide operating temperature range, reliable structure, and safety and convenience. The manual regulating valve blades are available in split and parallel opening styles, serving as regulating valves in ventilation, air conditioning, and air purification systems.