In a direct acting solenoid valve, a coil magnetically opens the valve in a direct action, lifting the shaft and the seat of the valve without depending on outside pressure.
Compressed air is hot, wet, and dirty. Air filters clean contaminants from compressed air to insure proper, consistent operation and to reduce wear on mechanical parts.
In pilot operated valves, the plunger opens up the pilot opening while built-up pressure causes the valve to open and close. Although piloted valves require less electrical energy to operate, they usually need to maintain full power in order to remain in an open state, and they perform at a slower rate than direct acting solenoids. Direct acting solenoid valves only need full power when opening the valve, as they can hold their open position even when operating on low power.