Portable water-spray nozzles are manual firefighting devices usually provided to supplement automatic firefighting equipment. They are suitable for use on fires in ordinary combustibles, in flammable liquids with flashpoints above 150°F (66°C) either spilled or in open tanks, and in oil-filled electrical equipment. The three kinds of fires and the types of nozzle FM Approved for them are: A. Ordinary Combustibles . While any spray nozzle listed is to some extent suitable for use on fires in ordinary combustibles, those with narrow angle discharge are FM Approved because of their effective range. B. Flammable Liquids with Flashpoints above 150°F (66°C) . Nozzles FM Approved for use on fires in flammable liquids with flashpoints above 150°F (66°C) in open tanks produce a cone angle discharge not less than 120°. To permit close approach for maximum effectiveness, they must be equipped with 6 through 12 ft (1.8 through 3.7 m) lightweight applicators. FM Approved nozzles discharging a narrow angle (30°-90°) high-velocity spray are effective for controlling flammable liquid spill fires, fires in open tanks containing flammable liquids with flashpoints above 200°F (93°C) and for cooling closed containers exposed to heat. They are generally not suitable for extinguishing fires in lower flashpoint flammable liquids in open tanks or pans. C. Electrical Equipment. Nozzles FM Approved for use on fires in electrical equipment produce a long-range, narrow angle (30°-90°) high-velocity spray only. They are suitable for use on fires in oil-filled electrical equipment, such as small transformers and oil switches, at voltages up to 250,000 when used at a distance of not less than 8 ft (2.4 m). Electrical equipment should be de-energized, if possible, before anyone attempts to extinguish a fire in or near it. Nozzles producing a solid stream or those employing applicators are not suited for this type of fire. Explanation of listings . Hose threads are national standard unless otherwise indicated. Discharge and discharge angle are shown for 50 psi (345 kPa) pressure. FM Approval designations are as follows: A. Fires in ordinary combustibles. B1. Fires in flammable liquids with flashpoint above 150°F (66°C) in open tanks. B2. Fires in flammable liquids with flashpoint above 200°F (93°C) in open tanks, and for all spill fires. C. Fires in electrical equipment. Main suitability is listed first. Secondary suitability is given in parentheses. While all nozzles to some extent are useful on fires in ordinary combustibles, the A designation is affixed below only to those primarily intended for this class of fire. ...