OSHA General Industry Standards (29 CFR Part 1910) 1910.159: 1910.159 Automatic sprinkler systems

Applies to automatic sprinkler systems installed to meet a particular OSHA standard; systems installed in workplaces but not required by OSHA are exempt. Systems installed before the standard's effective date comply if they meet the NFPA or National Board of Fire Underwriters standard in effect when installed. Design must provide the discharge patterns, densities and water flow for complete coverage of the workplace or zoned subdivision, using only approved equipment and devices. The employer must properly maintain the system, perform a main drain flow test on each system annually, and open the inspector's test valve at least every two years to confirm operation. Systems installed for employee protection after January 1, 1981 need acceptance tests, with dates recorded, including flushing of underground connections, hydrostatic tests of piping, air tests in dry-pipe systems, dry-pipe valve operation and a test of drainage facilities. Each system needs at least one automatic water supply able to provide design flow for at least 30 minutes, with an auxiliary supply or equivalent protection when the automatic supply is out of service, except for systems of 20 or fewer sprinklers. Hose connections may be attached to wet pipe systems only where the water supply meets the combined sprinkler and standpipe demand. Piping must be protected against freezing and exterior corrosion, dry pipes installed so the system can be totally drained, only approved sprinklers used, older style sprinklers not substituted for standard sprinklers without a complete engineering review, and sprinklers protected from mechanical damage. Systems with more than twenty sprinklers need a local waterflow alarm that sounds on the premises when flow equals that of a single sprinkler. Sprinklers must be spaced for maximum protection area per head, minimum obstruction of the discharge pattern and suitable sensitivity, with at least 18 inches (45.7 cm) vertical clearance to material below. Hydraulically designed systems must be identified with location, number of sprinklers in the hydraulically designed section and the design basis, on signs at the valves or in central records available to OSHA.