Automatic sprinkler systems

The standard applies to all automatic sprinkler systems installed to meet a particular OSHA standard. See 1910.159(a)(1).

• This means if an OSHA standard requires a sprinkler system for employee protection, that system must meet the requirements in 1910.159.

Yes — a sprinkler system installed before the standard's effective date can comply by meeting the NFPA or NBFU standard that was in effect when it was installed. See 1910.159(a)(2).

• Record or keep documentation of the older standard used at installation so you can demonstrate compliance if inspected.

No — automatic sprinkler systems that are installed in workplaces but are not required by OSHA are exempt from the requirements of this section. See 1910.159(b).

• If you install sprinklers voluntarily, you still should follow good practice and applicable local codes, but OSHA's specific requirements in 1910.159 do not apply.

A sprinkler design must provide the required discharge patterns, densities, and water flow for complete coverage of the specific workplace or zoned subdivision. See 1910.159(c)(1)(i).

• Designs should be based on the hazards, layout, and hydraulics for the area protected—not on a generic template.
• Use a qualified designer and document the basis of the design.

Yes — employers must ensure that only approved equipment and devices are used in the design and installation of automatic sprinkler systems used to comply with this standard. See 1910.159(c)(1)(ii).

• "Approved" typically means listed or certified by a nationally recognized testing laboratory or meeting the applicable consensus standard; retain documentation of approvals.

Employers must properly maintain the system, perform a main drain flow test annually, and open the inspector's test valve at least every two years to ensure proper operation. See 1910.159(c)(2).

• Keep records of the annual main drain test and the biennial inspector's test valve operation.
• Follow manufacturer and NFPA guidance when performing these tests.

You must conduct proper acceptance tests and record their dates. Required tests include flushing underground connections, hydrostatic tests of piping, air tests in dry-pipe systems, dry-pipe valve operation checks, and tests of drainage facilities. See 1910.159(c)(3) and the specific items 1910.159(c)(3)(i)-(v).

• Keep dated records of these acceptance tests as part of your compliance documentation.

An automatic sprinkler system must have at least one automatic water supply capable of providing the design water flow for at least 30 minutes. See 1910.159(c)(4).

• Verify pump and supply sizing against the system hydraulic design to ensure 30 minutes at design flow.

An auxiliary water supply or equivalent protection must be provided when the automatic water supply is out of service, except for systems of 20 or fewer sprinklers. See 1910.159(c)(4).

• If your system has 20 or fewer sprinklers, that exception applies; otherwise plan for an auxiliary supply or other protection if the main supply is out.

Yes — employers may attach hose connections for fire fighting use to wet-pipe sprinkler systems provided the water supply can satisfy the combined design demand for sprinklers and standpipes. See 1910.159(c)(5).

• Ensure hydraulic calculations account for simultaneous use; do not reduce sprinkler protection by adding hose demand without verification.

Employers must protect automatic sprinkler system piping against freezing and exterior surface corrosion. See 1910.159(c)(6).

• Use insulation, heat tracing, or other measures in cold areas and select corrosion-resistant materials or coatings for exterior piping.

All dry sprinkler pipes and fittings must be installed so the system may be totally drained. See 1910.159(c)(7).

• Proper slope, drain valves, and design practices are required to ensure complete drainage and prevent trapped water that could freeze or cause corrosion.

Yes — employers must ensure that only approved sprinklers are used on systems. See 1910.159(c)(8)(i).

• Use sprinklers listed or certified to the appropriate standards and retain approval documentation.

No — older style sprinklers may not be used to replace standard sprinklers without a complete engineering review of the altered part of the system. See 1910.159(c)(8)(ii).

• An engineering review ensures the change won't negatively affect hydraulics, coverage, or system performance; document the review and approval.

Employers must assure sprinklers are protected from mechanical damage. See 1910.159(c)(8)(iii).

• Protection can include guards, proper placement, or barriers where forklifts, stock, or other activities could strike sprinkler heads.

A local waterflow alarm that produces an audible signal on the premises must be provided on all sprinkler systems having more than 20 sprinklers; it must sound upon waterflow equal to a single sprinkler's flow. See 1910.159(c)(9).

• Test and maintain the alarm so it will operate when water flows in the system.

Employers must space sprinklers to provide the maximum protection area per sprinkler, minimize interference with the discharge pattern, and ensure suitable sensitivity to hazards; the minimum vertical clearance between sprinklers and material below must be 18 inches. See 1910.159(c)(10).

• Avoid obstructions like beams or high shelving that interfere with spray patterns; follow the system's hydraulic and layout design.

Employers must identify hydraulically designed automatic sprinkler systems or portions of them and indicate the location, number of sprinklers in the hydraulically designed section, and the basis of the design. See 1910.159(c)(11).

• Keep labels or central records that show the design basis and sprinkler counts so inspectors can review them.

Yes — central records may be used in lieu of signs at sprinkler valves provided the records are available for inspection and copying by the Assistant Secretary. See 1910.159(c)(11).

• Ensure records are organized and readily accessible during inspections to demonstrate compliance.

Yes — employers must conduct proper acceptance tests on sprinkler systems installed for employee protection after January 1, 1981, and record the dates of such tests. See 1910.159(c)(3).

• Include the dates and results of flushing, hydrostatic testing, air tests, dry-pipe valve operation, and drainage tests in your records.

Complete coverage means the sprinkler design must deliver required spray patterns, densities, and water flows so that the protected area or zone receives adequate suppression according to the system design. See 1910.159(c)(1)(i).

• Achieving complete coverage typically requires following the hydraulic design, avoiding obstructions, and using approved sprinklers sized and placed per the engineered plan.