Slow-start valves are used to safely build up pressure in pneumatic systems and serve as safety protection. The air inlet is connected to the input P of the slow-start valve. If the coil is energized, the three-port two-position valve opens. At this time, a small amount of air passes through the throttle valve to the output A, causing the system pressure to slowly build up;when the output pressure is equal to the input When the pressure is half, the slow-start valve is fully opened, and the flow rate reaches its highest value at this time. When the coil is powered off, the air inlet P is closed, and the air returns to the R port through the one-way valve and is quickly discharged. The system pressure drops to zero, which provides safety protection for the entire system.