Us duct’s automatic blast gates are pneumatically operated and electrically controlled. the pneumatic cylinders require 90 psi to operate but use very little volume. an electric solenoid directs the flow of the air to the cylinder for opening and closing. The solenoids are available in varied voltages (12/24v ac/dc, 120 and 220 line voltage). They can be wired to any electrical source and are typically wired so that the gates open when the machine is activated.