Standpipe Systems Design & Operation PDF

OBJECTIVE 3 Describe the design and operation of a typical standpipe system STANDPIPE SYSTEMS The practical height limit for firefighters to couple hoses together from street level, up stairways to the fire floor is 3stories (14 metres). It is also near the limit at which a fire can be fought exter...

OBJECTIVE 3 Describe the design and operation of a typical standpipe system STANDPIPE SYSTEMS The practical height limit for firefighters to couple hoses together from street level, up stairways to the fire floor is 3stories (14 metres). It is also near the limit at which a fire can be fought externally from ladders and snorkel equipment. Standpipe systems deliver firefighting water to higher levels in a building. The standpipe rises up the stairwell(s). At each floor level, provision is made for the connection of fire hoses. The firefighters need only to couple hoses to one of the valved outlets provided on the standpipe to get a water supply. The connections used are usually on the floor below the fire, allowing the fire to be safely approached from below. Most building codes accept the NFPA (National Fire Protection Association) Code 14,Standard for the Installation of Standpipe and Hose Systems as an integral part of their fire system code. The following descriptions can be found in more detail in NFPA-14. Classes of Standpipe Systems There are three classes of standpipe systems: • Class I systems provide 65 mm hose and connections. These systems are intended for use by fire departments and those trained in handling heavy fire streams. • Class II systems provide 40 mm hose and connections. These systems are intended for use by trained personnel or by the fire department during initial response. Subject to approval of the local fire authority, a minimum 25 mm hose and connections can be used in class II service in light hazard occupancies. • Class III systems provide 40 mm hose stations, and 65 mm hose connections. These systems are intended for use by trained personnel to supply a larger volume of water for use by fire departments. The number and location of standpipes and equipment is dependent upon the use, occupancy, and construction of the facility. Provincial and local authorities govern the fire acts, codes, and regulations. In general terms, the number of standpipes and hose stations are the same for each class. Page 18 of 44 In each building, and in each section of a building divided by fire walls, there must be standpipes and hose stations such that all portions of each story of the building are within 9 m of a nozzle attached to no more than 30 m of hose. Where a 25 mm hose has been approved in class II service, all portions of each story of the building must be within 6 m of a nozzle attached to no more than 30 m of hose. The standpipe risers are to be located in non-combustible, fire-rated stairwells. If it is not possible to locate all standpipes in fire-rated stairwells, then additional standpipes may be located in pipe shafts at the building interior column locations. For class I and III service systems, at least one 65 mm roof outlet connection shall be provided from each standpipe. Figure 10 illustrates a typical roof manifold system. The hose connections to the standpipe for Class I service should be located in the stairwell. For class II service, the hose connection should be located in the corridor or space adjacent to the stairwell. For class III service, the DN 65 (NPS 272) hose connection should be located in the stairwell, and the 40 mm hose connection should be located in the corridor or space adjacent to the stairwell. Where the building has a large area, the connections DN 65 (NPS 272) and DN 40 (NPS P/2) for class III may also be located at building interior columns. Standpipes for risers of less than 30 m are usually DN 100 (NPS4) pipe. If the riser is greater than 30 m, the pipe is usually DN 150 (NPS6). Where a building has a high-level fire zone (i.e., floors more than 85 m above street level), then the riser to these higher floors is usually DN 200 (NPS8). Page 19 of 44 The water pressure at the topmost outlet of each standpipe should not be less than 450 kPa, with a flow rate in the system of 32 litres per second (L/s). If the flowing pressure at any hose valve outlet will exceed 690 kPa, then a pressure reducing system shall be installed to reduce the pressure, at the required flow, to no more than 690 kPa. Note The abbreviations DN and NPS stand for diameter nominal and nominal pipe size respectively. Wet and Dry Standpipes There are two basic standpipe systems. A wet standpipe is one that is always filled with water. A dry standpipe is one that is normally dry and terminates at its base, outside the building, with a fire department connection. If a fire requires fire department participation, a pumper engine will connect to a nearby street hydrant and discharge water into the standpipe system through the fire department connection. The fire department connection is a special Y-piece, called a Siamese connection, which allows two hoses to simultaneously feed the standpipe (as shown in Figure 11). A Siamese connection is also provided on a wet standpipe system. Class II and class III systems must be connected to a wet standpipe system since the 40 mm hose system must have water available immediately. Figure 12 shows a schematic of a typical single zone system, well figures 13 and 14 show systems for buildings with two fire zones. Fig 12 Typical Single Zone Standpipe System Fig 13 Typical Two Zone Standpipe System Fig Typical Single Zone Fig12 14Typical Two Zone Standpipe StandpipeSystem SystemWith withVertically Staged Pumps Vertically staged Pumps Page 20 of 44