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NFPA 30 vs ACGIH approach to ventilating liquid storage areas

Question asked by laura.radle on Nov 16, 2020
Latest reply on Nov 19, 2020 by toddlaberge

I'm working on a liquid storage area and with regard to ventilation, Section 18.6.1 & 18.6.2 of NFPA 30 (2018) require a horizontal air flow in liquid dispensing areas to ensure movement across all portions of the floor and prevent accumulation of flammable vapors.  This is contrary to guidance provided by the American Conference of Governmental Industrial Hygienists (ACGIH), which requires vertical airflow- exhaust intakes to be installed on the room walls near the floor, with make-up air entering through the ceiling.


Can NFPA elaborate on the background as to why a horizontal flow is specifically called out in NFPA 30?  Industrial hygienists are concerned that the NFPA 30 approach will not reduce vapor concentrations in the employees breathing zone.