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NYC Mechanical Code

§ 502.9.5.1 — § 502.9.5.1

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What is NYC MC § 502.9.5.1?

Quick Answer

This section mandates that vaults containing Class I liquids must have continuous ventilation at specified rates and conditions. It requires automatic shutdown of the dispensing system in case of exhaust airflow failure or detection of flammable vapors. Applies to operators of facilities with such vaults.

General informational summary. Not legal advice for your situation. Consult an attorney before acting on any specific matter.

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502.9.5.1 Vaults.

MC § 502.9.5.1

Vaults that contain tanks of Class I liquids shall be provided with continuous ventilation at a rate of not less than 1 cfm/ft 2 of floor area (0.00508 m 3 /(s • m 2 )), but not less than 150 cfm (4 m 3 /min). Failure of the exhaust airflow shall automatically shut down the dispensing system. The exhaust system shall be designed to provide air movement across all parts of the vault floor. Supply and exhaust ducts shall extend to a point not greater than 12 inches (304.8 mm) and not less than 3 inches (76.2 mm) above the floor. The exhaust system shall be installed in accordance with the provisions of NFPA 91. Means shall be provided to automatically detect any flammable vapors and to automatically shut down the dispensing system upon detection of such flammable vapors in the exhaust duct at a concentration of 25 percent of the LFL.

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