PT400 Exterior Display is typically mounted on the main backboard close to the tank fill pipes. It is used to initiate measurements which provide operators/truckers with tank content information before, during and after filling operations. It is housed in a rugged weather proof enclosure. This exterior display supports up to 16 tanks. It measures: height, volume, ullage, and temperature corrected volume. During fill monitoring, it measures ullage, volume and height. The LED display shows the user: “SPILL”, “CAUTION”, “DANGER” and indicate “LOW N2”. The large keypad allows gloves to be used when pressing keys. It can also may be configured to allow only one tank to be in fill monitoring at a time or to allow multiple tanks to be filled at a time. The exterior display can be set up to work with on site pump shutdown units, refusing to allow pumps to operate until Fill Monitoring is entered.