Perancangan Sistem Peringatan Dini Bahaya Kebakaran Berbasis Infrared Fire and Gas Detector dengan Voting Logic 2oo3 dan Verifikasi Safety Integrity Level pada Terminal BBM PT XYZ

Fuel terminals store large volumes of volatile hydrocarbons, and a leak can form a flammable vapor cloud that may escalate into a fire or explosion. A root cause analysis at the PT XYZ fuel terminal in Semarang found no fixed vapor cloud detection. This study designs an infrared fire and gas detection-based early warning system that detects leaks, alerts operators, and triggers automatic protection, and verifies its reliability against IEC 61508/61511. Methods include a 5×5 risk matrix, orifice leak rate calculation, Gaussian plume dispersion with 2020–2024 BMKG wind data, 2oo3 voting and electrical design, Layer of Protection Analysis (LOPA), and PFDavg calculation with OREDA data. Leak rates through a 10 mm hole range from 0.32 to 1.45 kg/s, giving conservative 20% LFL hazard radii of 30–66 m. The design uses 22 infrared detectors in five zones with 2oo3 voting on a 1oo2D Safety PLC, lowering the false alarm probability to 0.12% while keeping the sensor PFD at 0.73%. The total PFDavg is 7.53×10−3 (SIL 2) with a risk reduction factor of 133, making it a suitable protection layer for the terminal. The motor operated valve contributes 87.2% of the total PFDavg, making final element redundancy the most effective improvement.