Foam Nozzle

DTL upright and pendent foam-water sprinklers are air-aspirating foam discharge outlets for foam-water deluge systems. They are for flammable liquid risks where foam is to be applied from overhead sprinklers, followed by plain water in a standard spray pattern, as NFPA 16 describes for foam-water sprinkler and foam-water spray systems.

The end user should confirm the materials of construction suit the corrosive environment: ambient temperature, chemical concentration and gas or chemical velocity all bear on it.

Operation

The body is a venturi. As foam solution flows through the inlet, air is drawn in through openings beside the wrenching area; solution and air are agitated together into an air-aspirated foam. The sprinkler discharges foam in a predetermined pattern and, once the concentrate is exhausted, water much as a standard spray sprinkler does — which NFPA 16 requires.

Design criteria

The sprinklers are for systems designed to the installation rules for foam-water sprinklers recognised by the listing agency (UL listing is based on NFPA 13 and 16). The applied density of foam solution must meet the authority having jurisdiction for the liquid and occupancy. Under NFPA 16 the density must be at least 0.16 gpm/ft² (6.52 mm/min) of floor area, at a discharge pressure of at least 30 psi (2.1 bar).

Installation

Tighten the ½" NPT joint to 7 to 14 ft-lb (9.5 to 19.0 Nm), using the wrench flats only. Higher torque can distort the inlet and impair the sprinkler.