Safe LPG Storage Geometry for Dense Housing: Hazard Radii, Minimum Separation, and a Communal Vented Store Design

Household LPG cylinders stored on balconies, in alleys and in dense courtyards place neighbouring dwellings inside their hazard radii. From stated simplified models for a jet fire, a flash fire and a vessel burst with fireball, for 5 kg, 15 kg and 45 kg propane cylinders, the governing separations are 7.17 m, 12.52 m and 21.52 m (design values 8 m, 13 m and 22 m), governed in every case by the fireball thermal-dose distance. Jet-fire radii are 3.45 m at 4 kW/m2 for all sizes; flash-fire radii are 3.93 m, 5.66 m and 8.16 m. A small-leak venting requirement of 0.71 m2 free vent area (0.53 m2 low level) is derived. Where available separation is 4.0 m, 2.0 m or 1.5 m no practical individual separation exists even for 5 kg, and the design must change to a communal vented store: 20 households, 5 fire cells of at most 4 x 15 kg cylinders, 12.0 m by 1.8 m by 2.1 m, placed at least 13 m from dwellings, costing 4854.08 USD total or 242.70 USD per household protected, versus 145.0 USD for an individual cage where separation can be met. SIMULATED, NOT MEASURED.