Fire Fighting Agents – What Is Piping

Importance of Fire Protection System Fire Protection systems are a very important part of safety in any operating plant as it provides a reasonable degree of protection to expensive equipment, property, documents, life, and inventory during a fire event. For Oil & Gas, Refinery, or plants those deals with Petroleum or similar flammable products, It must have to be in place to avoid major loss during uneven circumstances. A Fire requires combustible materials, oxygen, and an energy source (heat) to provide ignition. Three components - fuel, oxygen & heat are referred to as the fire triangle. Principle of Fire Extinction: Starvation - Removing or blanketing the fuelSmothering - Cutting off or diluting the oxygen supplyCooling - Removing heat from the fire. Fig. 1: Principles of Fire Extinction Types of Fire & Extinguishing Medium: Fig. 2: Types of fire and extinguishing medium Fire Fighting Agents: Fire Fighting Agents are those substances that are used to reduce the effect of fire during fire events. Examples are: SandBlanketingWaterSteamCarbon dioxideDry Chemical PowderAqueous Film Forming Foam (AFFF) Properties of Petroleum Products: For all flammable liquids, it is the vapor that burns and not the liquid.Petroleum vapor is heavier than air so it has a tendency to descend on the ground or lower level or sump.Petroleum is immiscible with water. Its specific gravity is less than 1, so they float on waterThe electric conductivity of almost all petroleum products (except crude oil, ethanol, etc.) is very low and hence it generates static electricity during storage and transportation Petroleum Products are divided into the following classes Class A - Flashpoint 23 deg.C & 65 deg.C & 93 deg.C & above Fire Protection Facilities in Petroleum Installations: Fig. 3: Fire Protection Facilities Codes and Standards for Fire Protection System Design The following reference codes and Standards govern the design of Fire Protection System Design. NFPA 24 – Standard for the Installation of Private Fire Service Mains and Their AppurtenancesNFPA 13 – Standard for the Installation of Sprinkler SystemsNFPA 15 – Water Spray Fixed SystemNFPA 11 – Standard for Low, Medium and High expansion foamNFPA 16 – Standard for the Installation of Foam water sprinkler and Foam water Spray systemNFPA 20 – Standard for the Installation of Stationary Pumps for Fire ProtectionNFPA 22 – Standard for Water Tanks for Private Fire ProtectionNFPA 30 – Flammable and Combustible Liquids CodeIP 19 – Fire Precautions at Petroleum Refineries and Bulk Storage installationsDEP 80.47.10.31-Gen – Active fire protection systems and equipment for onshore facilities Fire Protection System Design The firefighting system should be designed based on Single Fire Scenario.The Facility should be divided into zonesThe type of Fire Fighting system should be decided.Fire-Water application rate and discharge time should be referred from IP-19 or NFPA standards.Firewater demand for the facility should be calculated.Similarly, the water required for the Foam system should be calculated.The facility with the highest water demand is considered critical and based on this the Firewater storage tank and pump capacity should be determined. What are the different types of fire protection systems? Fire-Water Tanks: Above ground storage tanks of adequate nos. to meet the norm of 2 hr. continuous firefighting (As per IP-19).Fire-Water PumpsHydrant NetworkWater Spray SystemFoam Pourer System Fire-Water Pumps Fire-Water Pumps (Fig. 4) should be selected based on the largest fire water demand for the facility. Fire-Water Pumps should be selected as per NFPA requirements Firewater pumps should be three basic types as a minimum: Electrical Driven Pumps – Primary Considered as cost-effective but not mandatoryDiesel Driven pumps – Secondary considered but mandatoryJockey pumps – Required to the keep the hydrant system pressurized and to check the health of the Fire Water system Fig. 4: A figure showing a Fire Water Pump Hydrant Network in Fire Protection System Hydrant Networks (Fig. 5) consists of Hydrant and Monitors.Hydrants and Monitors should be placed at least 15 meters away from the hazard but not more than 45 meters.Proper coverage should be checked for the hydrant and monitors ensuring the facility under protection is adequately covered.The hydrant mains can be laid above ground or underground.The hydrant mains should form closed-loop ensuring multi-directional flow in the system. The layout should be such that the facility has access to Fire protection at any given time.Isolation valves should be located at branches and other strategic locations. Fig. 5: Figure showing a typical hydrant network Water Spray System as Fire Protection System The water spray system (Fig. 6) is provided for cooling of the tank shell, piping exposed to fire. The system is provided for cooling of the structure on fire and exposure protection of adjacent propertyThe system consists of fixed piping with pipe fittings, isolation valves, NRV and water spray nozzles.In the case of tank and piping, the water spray is directly impinged on to the surface of the tank or piping for cooling.Spray ring should be installed between each tank wind girder.NFPA 13 and NFPA 15 requirements should be metTwo types: Manual Water Spray system and Automatic Water Spray system Fig. 6: Typical Water Spray System Use of Foam Pourer System (Fig. 7) in Fire Protection: Semi-fixed foam Pourer system - Comprises of fixed pipings and pipe fittings, drain valves, foam coupling, foam makers, foam pourer and deflector plate on tank.Mobile Foam tender is required for actuating the system.Fixed foam pourer system( Manual/Automatic) - Manual system comprises of fixed foam concentrate storage shed, foam supply pumps, proportioning system, pipings, and pipe fittings, isolation valves, drain valves, foam coupling, foam makers, foam pourer and deflector plate on tank.The automatic system requires motor operates valves at different points and PLC for its actuation based on feedback from automatic fire detection and alarm system. Fig. 7: Typical Foam Pourer System Extinguishing System for Fire Protection Fire Extinguisher – CO2, DCP, Clean AgentClean Agent System – FM 200, Halon, etc.Sand Buckets Some more References for you Piping Design and Layout Piping Stress Analysis Piping Interface Piping Materials Piping Design Softwares References: https://www.nfpa.org/https://apps.dtic.mil/dtic/tr/fulltext/u2/a095040.pdf