At 2 pm., due to fluctuations in the composition of the fuel gas, the flare pilots extinguished one by one, causing the release of 23 t of cracked gas (C1/C2/C3) in a petrochemical company. The flare is fuelled instead of natural gas, with fuel gas from another installation in the process of being restarted, thus causing fluctuations. The technicians had to face 3 700 alarms during restart operations, so they overlooked the alarm of the flare. The flare pilots were manually re-ignited because the auto-ignition did not work. The operator changed the alarm system so that employees can give attention to the critical ones and changed the fuel system of the flare.