Section 61(1)(d) in The West Bengal Factories Rules, 1958
(d)all ventilation ducts, pneumatic conveyors and similar equipment involving a serious fire risk shall be provided with flame-arresting or automatic fire extinguishing [appliances, or fire resisting dampers electrically interlocked with heat sensitive/smoke detectors and the air conditioning plant system; and] [Substituted by W. B. Factories Amendment Rules, 1991, dated 27.11.1991.]