Fire Water Demand

The process area has combustible gas detectors, fireproofing, and a water deluge system. Cable trays are protected with deluge, and portable dry chemical extinguishers are in the process area. Diesel-powered fire water pumps can provide a maximum fire water demand for 4 hr. 

Determining fire water demand and duration of worst-case fire scenarios. 

Structures with equipment on two or more levels, not protected by water spray or deluge systems, should be counted as double the grade area beneath the multilevel structure plus the areas as noted above. Where fixed water spray systems are provided, their water requirements should be added to the fire water demand. Water demands for other areas within a plant may include ... 

Normally, fire water demands range between 2,000 and 10,000 gpm (7,600 to 38,000 Ipm). The design capacity of the fire water system should be at a minimum four (4) hours of continuous operation of the largest fire water demand. The capacity is based on a number of factors, including ... 

Figure 7-8. Example Fire Water Demand Method...

It is common practice to provide pumping capacity so that when the largest fire water pump is out of service, the total fire water demand can still be met. In situations where the demand does not exceed 1,500 gpm (5,700 Ipm), it may be acceptable to use a single pump. 

Distribution system-This system should cover all facets of outside fire protection water demands in order to provide adequate water distribution for existing conditions and the possibility of plant expansion. 

In areas where the water demand of the plant may exceed the supply capacity of the local mains, it will be necessary to install additional storage tanks. It is likely that if the local supply is subject to low flow rates additional storage is already available for services such as fire protection. 

Electricity, Valves, Heaters Fixed Protection Fire Areas, Water Demands,... 

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. 

Most hydrocarbon facility process areas and high volume storage areas have standardized on a minimum supply or availability of four hours of firewater for the WCCE. The performance of risk analysis may reveal the level of fire water protection may be more or less than this requirement. Once a detailed design is completed on a facility or if a verification of existing water demands is needed, a simple tabular calculation of firewater requirements can be made. This table can be used to document spray density requirements, duration levels, code requirements and other features. Table 23 provides and example of arrangement to document such information. 

For onshore facilities, water may be supplied from local public water mains, storage tanks, lakes and rivers. In these cases a conventional horizontal pump is used. The preferred design for onshore fire water pumps is a horizontal centrifugal type with a relatively flat performance curve (i.e., pressure versus quantity). The discharge pressure is determined by the minimum residual pressure required at the most remote location of the facility flowing its highest practical demand with allowances added for piping friction losses. 

On large fire water systems, the location of pumps and storage tanks at various plant areas provides greater reliability of protection and results in less pressure drop between the pump and the area of demand. Net positive suction head (NPSH) requirements and friction loss in the piping should be considered in locating fire water pumps. 

The water demand for enclosed process structures may depend on the degree of compaitmentalization by solid floors and the number of separate systems used to protect the structure. At a minimum, ground floor systems should be assumed to operate in a spill fire scenario. But, if water spray systems are used, it should be assumed that all systems will operate in order to estimate maximum water demand. 

If soluble anhydrite is desired, firing is maintained until a second boil occurs accompanied by a second temperature plateau at about 190°C. Virtually all the water of crystallization has been removed at 215°C. Soluble salts are impurities that increase the vapor pressure within the kettle. Aridized stucco refers to ketde-calcined hemihydrate that has been made with the intentional addition of 0.55—1.1 kilograms of NaCl or CaCl per metric ton of land plaster. The stucco characteristic of lower water demand permits higher density and higher strength casts. The hygroscopic nature of the chlorides prevents the use of aridized stucco for some applications. 

Table 18.3 shows a breakdown of the water requirements for the DOE base case NGCC and PC-fired power plants discussed in the previous section. Cooling tower use dominates the water demand with only a small fraction of water used for steam turbine makeup. 

A further example in WWERs is the seismic qualification of systems important to safety, especially ventilation systems which should be safety-graded but are not, and safety support systems like the service water pumps, fire water supply pumps and indication and recording instrumentation. Since fliese are not qualified with respect to seismic loads, their functional capability on demand in the case of an earthquake would be questionable. 

It is also feasible, during periods of extreme high temperature, that the risk of bush fire and perhaps even explosions of fuel tanks, etc. are possible. The combined effect of these hazards however, is no more severe than the individual consequences. The greatest risk to nuclear safety would be during periods of drought and high ambient temperature when a demand is put on the fire water supplies. 

The material is not considered a fire hazard, although flammable ammonia gas may be released in a fire. The chemical may explode if mixed with oxidizers, such as potassium nitrate, potassium nitrite, and potassium chlorate. Use any means suitable for extinguishing surrounding fire. Water spray may be used to keep fire-exposed containers cool. In the event of a fire, wear full protective clothing and NIOSH-approved self-contained breathing apparatus with full facepiece operated in the pressure demand or other positive pressure mode. 

The largest volume of hydrauHc fluids are mineral oils containing additives to meet specific requirements. These fluids comprise over 80% of the world demand (ca 3.6 x 10 L (944 x 10 gal))- In contrast world demand for fire-resistant fluids is only about 5% of the total industrial fluid market. Fire-resistant fluids are classified as high water-base fluids, water-in-oil emulsions, glycols, and phosphate esters. Polyolesters having shear-stable mist suppressant also meet some fire-resistant tests. 

SNR s fluidized-bed cogeneiation system is an early example of the commercial development of AFBC technology. Foster Wheeler designed, fabricated, and erected the coal-fired AFBC/boHer, which generates 6.6 MWe and 37 MW thermal (also denoted as MWt) of heat energy. The thermal energy is transferred via medium-pressure hot water to satisfy the heat demand of the tank farm. The unit bums 6.4 t/h of coal and uses a calcium to sulfur mole ratio of 3 to set the limestone feed rate. The spent bed material may be reiajected iato the bed as needed to maintain or build bed iaventory. The fly ash, collected ia two multicyclone mechanical collectors, may also be transferred pneumatically back to the combustor to iacrease the carbon bumup efficiency from 93%, without fly ash reiajection, to 98%. 

Water supply - It is the most important of all extinguishing agents for most chemical plant fires. The water supply should be sufficient to fulfill the demand for automatic protection and hose streams for at least a four-hour period. Allowance should be made for explosion damage to the system and protection against freezing. 

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