The Series 1831 differential pressure switch with manual reset is designed to eliminate common problems associated with high-duct-static-cutout installations. It requires no power to drive its outputs, eliminating the need for a separate power loop and its associated additional wiring and conduit. Both control contacts activate simultaneously, so the lead switch shutting down the fan and preventing the lag switch from sending an alarming signal to the direct digital control is no longer a probable system liability. —Dwyer Instruments, Inc.