Vane-type, explosion-proof waterflow detectors shall be installed on system piping on the drawing and/or as specified herein. Detectors shall be mounted in hazardous locations classified as: Class I, Div. 1 and 2, Groups B, C, D; or Class II, Div. 1 and 2, Groups E, F, G; or Class III, Div. 1 and 2. Detectors shall mount on any clear pipe span of the appropriate nominal size, either a vertical upflow or horizontal run, at least 6˝ from any fittings which may change water direction, flow rate, or pipe diameter or no closer than 24˝ from a valve or drain. Detectors shall have a sensitivity in the range of 4 to 10 gallons per minute and a static pressure rating of 450 psi for 2˝–8˝ pipes. The detector shall respond to waterflow in the specified direction after a preset time delay that is field adjustable. The delay mechanism shall be a sealed mechanical pneumatic unit with visual indication of actuation. The actuation mechanism shall include a polyethylene vane inserted through a hole in the pipe and connected by a mechanical linkage to the delay mechanism. Outputs shall consist of dual SPDT switches (Form C contacts). Two conduit entrances (one of which is a knockout type) for standard fittings of commonly used electrical conduit shall be provided on the detectors. A grounding provision is provided. Enclosures shall be NEMA 4 listed by Underwriters Laboratories Inc. All detectors shall be listed by Underwriters Laboratories Inc. for indoor or outdoor use.