Fire Water Distribution System

Fire water distribution systems should be inspected and tested regularly to ensure water can be delivered to all locations as required. Table 10-3 summarized the inspection and tests for components in a fire water distribution system. 

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The following is a generic test procedure that may be used to perform a flow performance of fire water distribution systems. 

The project plan should encompass all aspects of a fire protection system, such as the underground fire water distribution system, fire pumps, aboveground water header, valving and standpipes, structural support, and detection and alarm systems. All work on the fire protection system must be coordinated with other work activities at the site or in the operating unit. The recommended installation practices for the different types of fire protection systems are covered in consensus standards, such as NFPA. The installation process is illustrated in Figure 9-1. 

Inspection, Testing, and Maintenance for Fire Water Distribution Systems... 

The fire water distribution system is kept pressurized by means of a jockey pump. In the event of a sprinkler trip, three large diesel driven pumps come on line as needed to supply the tremendous quantity of water which may be required. In order to prevent the water pressure from dropping, which would result in low water flow to the sprinkler nozzles immediately after they are opened, an electric switch panel allows the diesels to be started directly from an electric notifier system. This permits the diesels to get the start signal about the same time water begins to flow which reduces the unwanted initial pressure drop. 

Fire water distribution systems including hydrants, monitors, etc. 

Some new features of furnaces available today include variable speed blowers, which deliver warm air more slowly and more quietly when less heat is needed, and variable heat output from the burner, which when combined with the variable speed blower allows for more continuous heating than the typical fixed firing rate. Distribution system features can be sophisticated with zoned heating which employs a number of thermostats, a sophisticated central controller, and a series of valves or dampers that direct airflow or water to different parts of the home only when needed in those areas. 

A terrorist release of weapons of mass destruction damage to chemical and industrial plants, sewer lines, and water distribution systems and secondary hazards such as fires will result in toxic environmental and public health hazards to the surviving population and response personnel, including exposure to hazardous chemicals, biological substances, radiological substances, and contaminated water supplies, crops, livestock, and food products. 

Water distribution systems are designed on the basis of the maximum day plus flow for fighting fires or on the basis of the maximum hourly, whichever is greater. For emergency purposes, standby units are installed. 

Several series of field tests were conducted under different conditions. Row was discharged from a hydrant on EBMUD s water distribution system, through a fire hose and onto a fairly level paved and curbed street close to the curb. The water flowed down the street, into a drop inlet 160 ft downstream. The drop inlet led to an onsite storm drain system at EBMUD s wastewater treatment plant that flows into the headworks of the plant. 

Fire not only poses a risk to life and property it also has a significant impact on the environment. Environmental damage from fires can be both short and long term and, in the case of poiiutants from fires affecting groundwater supplies, may persist for decades or even longer. Rivers, sewers, culverts, drains, water distribution systems and other services all present routes for the conveyance of pollutants off-site and the effects of a discharge may be evident some distance away. 

Motor-driven, multistage reciprocating compressors have reportedly been the most popular choice for aeroderivatives. Motor-driven, oil-fiooded screw compressors are also used in some cases. High horsepower, multistage centrifugal compressors, similar to those used at many pipeline compressor stations, may be required for the newer heavy-duty units if the distribution pipeline pressure is insufficient (see Pipelines). Gas turbines have more stringent fuel-gas specifications in terms of cleanliness than do gas-fired boilers. Thus oil- and water-knockout systems, coalescing filters, and fine-mesh filters are used. 

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. 

With hot water units, time clock control can operate satisfactorily as automatic bypass valves built into the distribution system will help the heater to achieve its working temperature quickly. With steam boilers, it is important that the boiler reaches a reasonable working pressure before steam is allowed into the distribution system. For example, if boilers are left open to a system for an extended length of time while not firing they will quickly lose their pressure. This is not only wasteful of energy but eventually creates a problem on start-up. To... 

Several catastrophic fire incidents in the petroleum industry have been the result of the facility firewater pumps being directly affected by the initial effects of the incident. The cause of these impacts has been mainly due to the siting of the fire pumps in vulnerable locations without adequate protection measures from the probable incident and the unavailability or provision of other backup water sources. A single point failure analysis of firewater distribution systems is an effective analysis that can be performed to identify where design deficiencies may exist. For all high risk locations, fire water supplies should be available from several remotely located sources that are totally independent of each and utility systems which are required for support. 

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. 

The sizing of piping is based upon a hydraulic analysis for the water distribution network for the WCCE. The main delivery pipe should be sized to provide 150% of the design flow rate. A residual pressure and flow requirement at the most remote hydrocarbon process or storage location from the supply source dictates the sizing for the remaining system. Normal reliability requirements usually suggest that minimum of two sources of supply be available that are in themselves remote from each other. Therefore two remote flow calculations must be performed to determine the minimum pipe distribution size. NFPA 24 requires that the minimum residual pressure available in a fire main not be less than 6.9 bars (100 psi.). Velocity calculations should be performed which verify flows are not more than the limits of the material that is employed. 

American Water Works Association (AWWA), M31. Distribution System Requirements for Fire Protection. First Edition, AWWA, Denver, CO, 1989. 

Pressure maintenance (jockey) pumps should be provided to maintain a predetermined pressure on the system and make-up normal leakage in the distribution system. Normally, the pressure maintenance pump will maintain 10-15 psi (69-103 kPa) above the starting pressure for the automatic starting of the main fire water pump. (See 7.4.4.3.9.)... 

Other utility systems. Other utility systems required in a refinery are electric power distribution, instrument air, drinking water, fire, water, sewers, waste collection, and so forth. Since these are difficult to estimate without detailed drawings, the cost is normally included in the offsite facilities. 

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