The TV2 Clean Room Monitoring system uses the included Positive and Negative pressure sensor. The differential pressure sensor uses two tubes to measure the two different areas being compared.
If you want to measure positive pressure in a room, the positive pressure tube will terminate in the interior of that room and the negative pressure tube will terminate outside of the room. If you want to maintain negative pressure in a room, you would simply switch the tube locations.
The wall plate (shown left) provides a finished look and easy connection for the terminated ends of the positive and negative pressure tubes originating from the pressure sensor. They can be mounted with tubing running through wire chases inside the walls.