Water suppression systems

Water is the most useful and vital fire suppression medium, whether used for fixed systems or manual fire fighting efforts for petroleum facilities. It is relatively inexpensive and normally plentiful. It has enormous heat absorption properties. Approximately 3.8 liters (1.0 gal.) of water absorbs about 1,512 k cal (6,000 Btu), when vaporized to steam. Steam created by water evaporation expands to about 17,000 times its volume in open atmospheres, thereby limiting combustion processes by displacing oxygen in the area. 

When water is combined with other additives, it can control and extinguish most petroleum fires. A water suppression system consists of a supply source, distribution system, and the end using equipment such as fixed spray systems, monitors, hose reels and hydrants. The objective of water suppression systems is to provide exposure cooling, fire control, suppression of fire incidents and may assist in the dispersion of flammable or toxic vapors. 

When water suppression systems are provided, due concern should be made for the disposal of the released water. Of primary importance are the capacity and location of surface drainage systems. Fire water usage usually places greater demands on a facility gravity sewer system than rainfall or incidental petroleum spillage effects. 

---

The success of fixed water suppression systems depends on the following ... 

Oxidizer storage areas and flammable liquids storage areas require water- based fire suppression systems. While there are no reqnirements to keep water reactive materials away from oxidizers, when storing oxidizers, consideration should be given to the additional hazard posed by the presence of water reactive materials when water suppression systems are activated. 

Ensure the adequaey (in terms of quality, quantity and reliability) of serviees/utilities, e.g. steam, proeess/eooling water, eleetrieity, eompressed air, inert gas, fire suppression systems, ventilation. Stand-by or emergeney serviees may be required. Some general safety design eonsiderations are summarized in Table 12.11. 

Level-Float 3.2.1.5.2 Piping Systems-Metal-Welds Suppression Systems-Water... 

Taxonomy No. 4,2.3.2 Equipment Description PROTECTION SYSTEMS-FIRE- FIRE SUPPRESSION SYSTEMS-WATER ... 

A patented water injection system has been devised for extinguishing oil and gas well fires in case of a blowout. The "Blowout Suppression System" (BOSS) consist of finely atomized water injected to the fluid stream of a gas and oil mixture before it exits a release point. The added water lowers the flame temperature and flame velocities thereby reducing the flame stability. In the case where the flame cannot be completely dissipated, the fire intensity is noticeably deceased, preserving structural integrity and allowing manual intervention activities. A precaution in the use of such a device is that, if a gas release fire is suppressed but the flow is not immediately isolated, a gas cloud may develop and exploded that would be more destructive that the pre-existing fire condition. 

Hydrants should be considered as a backup water supply source to monitors and fixed fire suppression systems. Hydrants should be located on the ring main at intervals to suitably direct water on the fire hazard with a fire hose. Hydrants monitors and hose reels should be placed a minimum of 15 meters (50 ft.) from the hazard they protect for onshore facilities. Hydrants in process areas should be located so that any portion of a process unit can be reached from at least two opposite directions with the use of 76 meters (250 ft), hose lines if the approach is made from the upwind side of the fire. Offshore hydrants are located at the main accessways at the edge of the platform for each module. Normal access into a location should not be impeded by the placement of monitors or hydrants. This is especially important for heavy crane access during maintenance and turnaround activities. 

For means of protection, the use of water based suppression systems may be a hazard due to the disposal of firewater water, which will freeze quite readily in exposed locations. This may also be the case with exposed hydrocarbon fluid lines that, if isolated, say for an ESD activation, may freeze up due to lack of circulation. This will hamper restart operations for the facility. Typical use in the past has been the reliance on gases fire suppression agents for enclosed area, particularly Halon. Other methods include fire water storage tanks that are kept warm, together with fire mains deeply buried and continually circulated. 

Depending on the criticality and value additional fire suppression systems are provided for protection. NFPA 850 section 5-8.6 recommends that oil-filled station and start-up transformers at power generation plants be protected with a water or foamwater spray system. The most common installation is a fixed water spray. Where several transformers are provided, a firewall is commonly used to separate and protect one unit from another. 

Fixed installations, such as water spray systems, halon systems, sprinkler systems, carbon dioxide extinguishing systems, explosion suppression systems, and other fire protection installations are often provided with flow and trouble detection switches connected to transmitters. A signal indicating the condition of the system should be sent to the attended location(s). 

Water mist systems are intended for rapid suppression of fires using water discharged into completely enclosed limited volume spaces. Water mist systems are desirable for spaces where the amount of water that can be stored or that can be discharged is limited. In addition, their application and effectiveness for flammable liquid storage facilities and electrical equipment spaces continues to be investigated with optimistic results. Water mist systems are also used for gas turbine enclosure protection. 

II reaction under similar conditions at temperatures between 80 and 100°C and with a four-fold excess of 2-methylpentanal (to compensate for the low solubility), the selectivity for the Aldol II product (80%) was 20% higher in [BMIMJEF NaOH than in the water/NaOH system, both at 100% propanal conversion. The increased selectivity was attributed to the higher solubility of the reactant 2-methylpentanal in the ionic liquid phase than in the water phase. The higher solubility of 2-methylpentanal effectively suppressed the self-aldol condensation in the ionic liquid. 

Other fire protection features have been incorporated into CNG refueling facilities such as methane detectors to warn of leaks from the dispenser, and automated fire suppression systems activated by ultraviolet/infrared detectors. Dry chemical is the preferred fire suppression material since water line protection from freezing is difficult in outdoor settings. The methane detectors can also be used to shut down the compressor and dispenser if desired. 

A fire suppression system should be provided around the dispenser to protect personnel and vehicles from fire during refueling. Actuation shall be provided both by sensors automatically and through the use of a manual switch. LP gas tanks that can be exposed to fire should have water spray fixed systems to prevent the tanks from failure due to over-temperature. The direct application of water in the form of a spray can also be used to control unignited gas leakage. 

---