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8.3 Methane Detectors Each LNG fueling station is equipped with multiple methane detectors capable of measuring ranges from 0-100% of the lower explosive limit (LEL). The methane detectors are set to activate the alarm system at 20% and/or 40% of the LEL. Refer to the layout drawings for the location of each methane detector. ■ Methane Detection at 20%and 40%LEL The following safety measures take place automatically after a detection of 20%or 40% LEL ❑ The station and pumps shut down ❑ All air-operated valves close ❑ The alarm beacon illuminates 0 20% detection results in an amber beacon 0 40% detection results in a red beacon ❑ The alarm horn activates ❑ The Methane Detected Circuit on the fire alarm control panel activates ❑ The auto-dialer initiates communication to the Clean Energy Command Center or monitoring service ❑ A technician is dispatched ❑ The alarm is logged into the alarm system of the Programmed Logic Controller(PLC) ❑ 40% detection also results in disconnection of electrical power to all electrical equipment • Clearing the Alarm To clear a methane detection alarm,the following requirements must be met: ❑ Methane levels detected must fall below 20%of the LEL ❑ The alarm silence button on the front of the control panel must be pressed o This will silence the alarm horn, but will not clear the alarm or turn off the amber/red beacon ❑ The alarm reset button on the front of the control panel must be pressed o If the resent button is pressed while the detector is still reading 20%or more of the LEL,the alarm will remain active and the amber/red beacon will remain illuminated ❑ The alarm must be acknowledged on the Human Machine Interface (HMI)screen of the PLC control system on the front of the control cabinet In the case of a 40% Detection,there are some additional steps/requirements: ❑ Pressing the reset button on the control panel after a 40% detection will restore power to the pump skid and the fuel dispensers as long as the alarm conditions are cleared and the methane level detected onsite is below 40%of the LEL ❑ However no automatic process will be permitted to start ❑ Offloading and dispensing will also not be permitted to start until all alarms are cleared on the HMI screen of the PLC control system L/CNG Emergency Response Plan 4, Clean Enerav- 5