Regulating valves are divided into two types: direct acting type and indirect acting type. The direct-acting type is also called the spring-loaded type. There are elastic components in its structure: such as springs, bellows, bellows-type temperature bulbs, etc., and utilizes the principle of balancing elastic force and feedback signals. The indirect-acting control valve adds a pilot (pilot valve), which amplifies the feedback signal and then drives the main valve disc movement through the actuator to change the valve opening. Category: ZZY type direct-acting self-operated pressure regulating valve ZZV type direct-acting self-operated micro-pressure regulating valve ZZC type direct-acting self-operated differential pressure regulating valve ZZYPII type pilot-operated self-operated pressure regulating valve ZZW type self-operated temperature regulating valve ZZD type Nitrogen sealing adjustment device ZZFX explosion-proof fire-retardant breathing valve