Section 65.111 - Standards: Pressure relief devices in gas/vapor service(a)Compliance schedule. The owner or operator shall comply with this section no later than the implementation date specified in § 65.1(f) .(b)Compliance standard. Except during pressure releases as provided for in paragraph (c) of this section, each pressure relief device in gas/vapor service shall be operated with an instrument reading of less than 500 parts per million as measured by the method specified in § 65.104(b) and (c) .(c)Pressure relief requirements.(1) After each pressure release, the pressure relief device shall be returned to a condition indicated by an instrument reading of less than 500 parts per million, as soon as practical, but no later than 5 calendar days after each pressure release except as provided in § 65.105(d) .(2) The pressure relief device shall be monitored no later than 5 calendar days after the pressure release and being returned to regulated material service to confirm the condition indicated by an instrument reading of less than 500 parts per million as measured by the method specified in § 65.104(b) and (c) .(3) The owner or operator shall record the dates and results of the monitoring required by paragraph (c)(2) of this section following a pressure release including maximum instrument reading measured during the monitoring and the background level measured if the instrument reading is adjusted for background.(d)Pressure relief devices routed to a process or fuel gas system or equipped with a closed vent system and control device. Any pressure relief device that is routed to a process or fuel gas system or equipped with a closed vent system capable of capturing and transporting leakage from the pressure relief device to a control device meeting the requirements of § 65.115 is exempt from the requirements of paragraphs (b) and (c) of this section.(e)Rupture disk exemption. Any pressure relief device that is equipped with a rupture disk upstream of the pressure relief device is exempt from the requirements of paragraphs (b) and (c) of this section provided the owner or operator installs a new rupture disk upstream of the pressure relief device as soon as practical after each pressure release, but no later than 5 calendar days after each pressure release except as provided in § 65.105(d) .