PROTECTION FOR STORAGE TANKS

Storage tanks in some industries may carry potential hazard, ie fuel storage tank & flammable chemical liquid tank. Almost in every industries which is using liquid material for the production or store their final product in liquid form using storage tank. From single tank to multiple tanks as usually said tank farm.

3S-Firestop has designed and installed fire protection systems for storage tank, from single fuel storage tank to multiple storage tanks. The largest system ever installed was the protection system for Methanol Tank 5 x 5,000 MT. Our installations are in several power generating plant, bio-diesel plant, and chemical industries. Water spray and foam system using foam chamber are most common in this type of tank fire protection. Lets take a look :

Flame Detector

Flame often happens due to improper grounding, lightning strikes, spill and other cause. Install flame detector will give faster response for your fire alarm or fire releasing control mechanism. FlameSpec range of triple IR (IR3) and UV IR flame detectors are faster in detection time and perform over longer distances while maintaining and improving on false alarm immunity. The optional in-built High Definition (HD) video camera allows for live video streaming of the area being protected.

Gas Detector

Gas detectors can improve the safety of the area or in the perimeter of the hazard zone. Tank farm of Methanol tanks with Methanol Gas Detector can give early warning of a leakage if happens. This gas detector has analog 4 - 20 mA and RS-485 output which can be connected to the plant Emergency Shutdown System.

Fire Alarm & Release Control System

This is the heart of the whole system, this panel will collect all data / signal from the field instruments (detectors, manual pull station, pressure switches, tamper switches) and acts as per pre-programmed sequences to do the protection. For notification only, Fire Alarm Control Panel (FACP) fulfill the purpose. However if there's deluge water spray in the system, Fire Release Control Unit shall be used. Panel like Protectowire conventional release control panel model SRP-4x4, Mircom model FR-320 or more complex panel like Mircom model FX-3500RCU Addressable Fire Releasing Control, the selection depends on the complexity of the system built and the budget. The last model has input module that can accept 4 - 20 mA analog input.

Deluge System

Deluge valve is the heart of the deluge system. The spray system is controlled by deluge valve. When the fire alarm panel gets alarm signal, as pre pre-programmed configuration, a deluge valve may be actuated to initiate discharge. Reliable model DDX is the robust construction with minimum rubber parts. The maintenance is also simple. Just open the front cover to clean the interior of the valve. DDX Deluge Valve has range from 2", 2.5", 3", 4", 6" and 8" size. Stainless steel body material also available on request. For the isolating valve, Reliable has butterfly valve with hand wheel.

Spray Nozzles

The most common model for spraying water to the tank vertical surface is medium-velocity spray nozzle. There are various K-Factor and spray angle selection to suit to the design. Common material use is brass, but stainless steel also available. The purpose of the water spray system is to cooling the tank, temperature to reach boiling point of the tank content is not allowed.

Foam Systems

To avoid catastrophic fire damages and spreading of fire to the adjacent tanks in tank farm, foam solution is injected to the interior of the burning tank . To make proportional mix of Picture - 3 : Group of Deluge Valves of water and foam concentrate, Foam Bladder Proportioning Tank can be considered as it does not need external energy like electric foam pump. Horizontal or Vertical Tank available, however for large capacity > 1,500 gallon the option only the horizontal ones.

Foam Chamber used to mix foam solution with air and injected into the tank interior. Foam Chamber installation is the tank side wall. In case no spare flange is prepared at the tank side wall, another method of foam injection shall be considered.

High Back Pressure Foam Generators (HBPGs)

HBPG is used in subsurface foam injection system which are primarily designed for the protection of fixed roof tanks applicable for hydrocarbon fuels only. Designed to produce low expansion foam with an expansion of around 4:1, these Fixed Foam Generators will operate efficiently against a back pressure of up to 40% of the foam solution inlet pressure. The material is made of steel with coating and stainless steel. Six models are available with flows from 600 to 2000 LPM (160 to 530 GPM) to cater for a broad range of applications.

Foam Concentrates

There are numerous types of foam, but these days the synthetic foam concentrates are most common to apply. Environmentally Responsible FireFilm® foam concentrate is a superior quality aqueous film forming foam (AFFF) which is used at 1%,3% and 6% concentration to extinguish fires in hydrocarbon fuels. Most applications use 3% concentration as 1% more costly.

AFFF foam concentrates are designed for rapid fire knockdown by producing a thin aqueous film which spreads across the surface of the fuel, separating the fuel from oxygen. This is accomplished by allowing the foam solution to quickly drain from the foam bubble which in turn, improves long term sealability and burnback resistance. The aqueous film is produced by the fluorocarbon surfactant reducing the surface tension of the foam solution to the point where the solution can be supported by the surface tension of the fuel. All FireFilm®-AFFF fluoro-surfactants are based on C6 chain. Do NOT contain PFOS or PFOA and low energy input AFFF-requires minimal agitation.

AR-AFFF is used for polar solvent liquid like Methanol or Ethanol and other polarized liquid. AR-AFFF stands for Alcohol-Resistant Aqueous Film Forming Foam. FireFilm®-AR is an AR-AFFF concentrate with a special biosynthesized polymer. This polymer is designed to fulfill two functions. The first is to form a protective membrane between the fuel and the foam as it contacts the water-miscible fuel, making extinguishment possible. This layer will prevent the flammable vapor meets with Oxygen from the air. The second function is to make the foam more stable and heat- resistant, resulting in better burnback resistance and sealability compared to conventional AFFFs . Check this link.