UL Standards free download UL 2166 2021 pdf download – Halocarbon Clean Agent Extinguishing System Units UL 2166 2021 pdf download - Halocarbon Clean Agent Extinguishing System Units. 7 General 7.1 After discharge of the extinguishing agent is initiated, an extinguishing system unit shall maintain the maximum rate of application of the extinguishing... 02-09 Download Now