The Direct Low Pressure System (DLP) utilized the detection tubing as both fire detection as well as delivery system for the fire suppressant. The portion of the tube nearest to the fire will rupture with a nozzle-like opening. The pressure drop in the tube causes the release of the suppressant from the cylinder through this opening.
The Indirect Low Pressure System, the detection tubing act just as a fire detection device. The fire suppressant is delivered through metallic pipe or high pressure braided hose. Once the detection tubing rupture, the suppressant is discharged through strategically placed nozzles within the protection enclosure.