MVWS Nozzle Stainless Steel

MVWS nozzles are open (non-automatic) directional spray nozzles for fixed water spray (deluge) systems protecting special hazards. An external deflector discharges the water in a directional cone of fine droplets, distributed uniformly over the surface to be protected.

They apply water to exposed vertical, horizontal, curved and irregular surfaces; cool those surfaces and prevent excessive absorption of heat from an external fire, avoiding structural damage and the spread of fire; and control or extinguish the fire, depending on the water design density the applicable code requires.

Because the design intent of water spray systems varies considerably, the nozzle is made in several combinations of K-factor and spray angle, and may be oriented in any position the hazard requires.

Operating pressure

The minimum desirable pressure for a reasonable spray pattern is 1.4 kg/cm², and a change in pressure between 1.4 and 3.5 kg/cm² does not change the spray angle considerably. Published patterns are at an average of 2.0 kg/cm² in still air and apply between 1.4 and 4.2 kg/cm²; above 4.2 kg/cm² the pattern draws inward and the coverage area decreases. Consult DTL for pressures up to 12 kg/cm².

NFPA 15 requires a main pipeline strainer for systems using nozzles with an orifice smaller than 9.5 mm (⅜ inch) — K-41 and below — and wherever the water is likely to contain obstructive material.

Installation and maintenance

• Handle with care; store and ship in the original packing only.
• Do not install a nozzle that is visibly damaged.
• Apply Teflon tape or a soft thread sealant to the male thread of the nozzle only.
• Hand-tighten into the fitting, then use a nozzle wrench. Excessive torque can damage the arms and deflector and affect the spray pattern.
• Optional blow-off caps keep foreign material out of the waterway; the minimum operating pressure with a cap fitted is 1.4 kg/cm² (20 psi).
• Outdoors, the system designer must allow for wind velocity and any field obstructions affecting the pattern.
• Have authorised personnel inspect the system regularly for atmospheric effects and internal or external obstruction.
• Operate the system at full water flow at least twice a year, or as NFPA or the authority having jurisdiction requires.
• Design water spray systems to NFPA 15 and/or the applicable authority having jurisdiction.

Marking

Each nozzle body is marked with the DTL trademark, its K-factor and the year of manufacture.