20200112-Firefighting Systems Design By Elite Software- Eng. Iyad Alalem

DESIGN  Extinguishment of fires by water spray shall be accomplished by one or a combination of the following methods: a. Surface cooling ( ‫) تبريد السطح‬ b. Smothering by produced steam c. Emulsification ( ‫) استحﻼب‬ d. Dilution ( ‫) تخفيف التركيز‬ e. Other factors  Design Densities for various hazards, when demanded by other sections of this code or by Civil Defense hazard evaluation shall be as per following Tables.  The duration of Discharge shall not be less than 60 minutes.  All deluge water spray systems shall be hydraulically designed along with the manufacturer’s instructions.

DESIGN: Water Spray Design Densities and Criteria

Example Water Spray System for LPG gas Tank  Calculate the total area of the Tank a. Calculate the surface area of the Shell, A1= ������DL b. Calculate the area of the flat ends, A2= D2/4 c. Calculate the area of spherical (Concave or Convex) ends, A3= (D2/4+h2) d. Calculate the area of Hemispherical ends, A4= D2/2 e. Total Area of Tank, A = A1+A2+A3+A4

Example Water Spray System for LPG gas Tank  ii. Design Density Water Application Rate shall be d = 10.2 Lpm/M2 (2.7 Gpm/M2)  iii. Water Application Rate Required (Theoretical – Lpm) = A X d  iv. Establish minimum Pressure (Bar) required at remotest Nozzle. (As per manufacturer’s recommendations suitable to design density and area of application).  v. Establish minimum Discharge (lpm) through each Nozzle at the above stated pressure (Bar).  vi. Select number of Nozzles to be provided as per the coverage requirement.  vii. Find water required from each nozzle, = Q/No of nozzles  viii. Select appropriate Nozzle capacity i.e K-factor  ix. Adjust design as per calculated Flow and Pressure required at the tap off point.  x. Provide number of QBD Detectors as per the Coverage requirements.

Typical horizontal tank protection.

Typical Schematic for LPG Tank Water Spray System.

Typical Deluge Water Spray System Application for LPG Tank.