The Viking Quick Response Extra-Large Orifice Upright Sprinkler VK531 is a thermosensitive glass bulb spray sprinkler available in several different finishes and temperature ratings to meet design requirements.  The extra-large orifice provides greater flows at lower pressures than standard orifice or large orifice sprinklers. This feature allows reduced pipe sizing for hydraulically calculated sprinkler systems, which require high densities of water.  Viking Quick Response Extra-Large Orifice Sprinklers may eliminate the need for a fire pump or reduce the size of the pump if it is required.