Selection and specifications for fire pumps

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This post was last edited by tianyewei on 2017-3-15 08:47. Selection and application must comply with relevant regulations: 1. The performance of fire pumps shall meet the flow rate and pressure requirements of the fire water supply system； 2. The power of the drive associated with the fire pump must meet the power requirements at any point on the flow and head performance curve of the selected pump ； 3. When using a fire pump driven by an electric motor, a fire pump with the motor mounted dry should be selected ； 4. The flow-head performance curve should be a smooth curve without humps or corners; the pressure at zero flow rate should not exceed 140% of the design operating pressure, and it is preferable that it be greater than 120% of the design operating pressure ； 5. When the discharge flow rate is 150% of the design flow rate, the outlet pressure shall not be lower than 65% of the design operating pressure ； 6. The sealing method and material of the pump shaft shall meet the requirements for the operation of fire pumps at low flow rates ； 7. For fire water supply systems, the models of the fire pumps in the same pump set should be consistent, and the number of operating pumps should not exceed 3 ； 8. When multiple fire pumps are connected in parallel, it is necessary to verify the effect of flow accumulation on the outlet pressure of the fire pumps. 2 The main materials shall meet the specified requirements. 1. The pump casing should be made of ductile iron ； 2. The impeller should be made of bronze or stainless steel. When using diesel fire pumps, the relevant regulations must be complied with. 1. Diesel fire pumps should be equipped with compression-ignition type diesel engines ； 2. The rated power of the diesel engine should have its impact by altitude and ambient temperature on the engine’s power taken into account ； 3. Diesel fire pumps shall be capable of operating continuously, with a test operation time of not less than 24 hours ； 4. The battery of the diesel fire pump must ensure that the fire pump can start automatically at any time as required ； 5. The fuel tank for diesel engine fire pumps should be sized based on the duration of the fire, and its minimum effective capacity should be 1.5 L/KW. The fuel stored in the tank of such fire pumps should amount to no less than 50% of its total capacity. Axial flow deep well pumps are suitable for installation in wells, fire ponds, and other fire water sources. 3-axis flow deep well pumps shall meet the specified requirements. When installing an axis flow deep well pump in a water well, its submersion depth must be sufficient to ensure reliable operation. When the pump’s discharge volume is 150% of the design value, the minimum submersion depth should be at least 3.20 m above the water level at the bottom of the first pump impeller; in addition, for every increase of 300 m in altitude, the minimum submersion depth of the deep well pump must increase by at least 0.30 m ； 2. When an axial-flow deep well pump is installed at a fire water source such as a fire tank, the bottom of the first pump impeller should be below the lowest effective water level line of the fire tank. The submersion depth shall be determined through calculations based on hydraulic conditions, and it must ensure that the entire effective storage capacity or effective water level of the fire water source such as the fire tank can be utilized ； When the designed flow rate of the water pump is greater than 125 L/S, the submersion depth should be determined based on the pump’s performance, and it must meet the requirements regarding the pump’s net positive suction head ； 3. When the lowest water level in the fire tank is below the centerline of the outlet pipe of the centrifugal pump, or when the water level in the water source is not sufficient to ensure proper suction by the centrifugal pump, an axial flow deep well pump can be used; it should be installed in a wet-type deep pit configuration at the fire tank or other fire water sources ； 4. When the motor of an axial flow deep well pump is installed outdoors, it should have rain protection features ； 5. Other requirements shall comply with the relevant provisions of the current **standard, the “Code for Design of Outdoor Water Supply” GB 50013. A standby pump should be provided for the fire pump, and its performance should be identical to that of the working pump. 4 Buildings that do not require a backup pump: 1. Residential buildings with a height of less than 54 m, and buildings for which the designed flow rate of the outdoor fire protection water supply is 25 L/S or less ； 2. Buildings with an indoor fire protection water supply design flow rate of 10 L/S or less. A set of fire pump units shall be equipped with flow and pressure testing devices in the fire pump room. The flow and pressure testing devices in the pump room shall meet the specified requirements. 1. When the flow rate of a single fire pump is not greater than 20 L/S and its designed operating pressure is not greater than 0.50 MPa, the pump unit shall be equipped with interfaces for flow meters and pressure gauges for measurement; other pump units should be fitted with devices for testing their flow rate and pressure ； 2. The metering accuracy of the flow measurement device for fire pump systems should be 0.4 grade; 75% of the maximum head shall be greater than 175% of the design flow rate of the largest fire pump ； 3. The measurement accuracy of the pressure monitoring device for fire pump systems should be 0.5 grade; 75% of the maximum head value should be greater than 165% of the design pressure value of the largest fire pump ； 4. A DN65 test pipe should be installed on the outlet pipe of each fire pump, and drainage measures should be taken. 5 The water absorption rate shall meet the specified requirements. 1. Fire pumps shall have a self-priming suction system ； 2. When the fire pump draws water directly from the municipal water supply network, a backflow preventer equipped with an air separator should be installed on the outlet pipe of the fire pump ； 3. When there is no water intake well at the water intake, a swirl preventer should be installed there. 6 The suction pipes, discharge pipes, and valves of centrifugal fire pumps shall meet the specified requirements. 1 For a set of fire pumps, there should be no fewer than two suction pipes; when one of them is damaged or under maintenance, the remaining suction pipes shall still be able to handle the entire designed flow rate of the fire water supply ； 2. The suction pipe of the fire pump should be arranged in such a way as to prevent the formation of air pockets ； 3. A set of fire pump systems shall be equipped with no less than two main water supply pipes to connect to the circular fire water supply network; when one of these pipes is under maintenance, the remaining pipes shall still be able to handle the full design flow rate of the fire water supply ； 4. The submersion depth of the suction inlet of the fire pump shall meet the requirements for safe operation of the fire pump at the lowest water level. The submersion depth of the suction pipe nozzle below the lowest effective water level of the fire tank shall be determined based on the flow velocity and hydraulic conditions of the suction pipe nozzle, but it shall not be less than 600 mm. When a swirl preventer is used, the submersion depth shall not be less than 200 mm ； 5. A visible stem gate valve or a butterfly valve with a self-locking mechanism should be installed on the suction pipe of the fire pump; however, when a hidden stem valve is used, opening scales and markings must be provided ； When the pipe diameter exceeds DN300, it is advisable to install electric valves ； 6. A check valve and a gate valve with an exposed stem should be installed on the outlet pipe of the fire pump ； When a butterfly valve is used, it should be equipped with a self-locking device ； When the pipe diameter exceeds DN300, it is advisable to install electric valves ； 7. When the diameter of the suction pipe of the fire pump is less than DN250, its flow rate should be between 1.0 m/s and 1.2 m/s ； When the diameter is greater than DN250, it is advisable to use a value of 1.2 m/s to 1.6 m/s ； 8. When the diameter of the outlet pipe of the fire pump is less than DN250, its flow rate should be between 1.5 m/s and 2.0 m/s ； When the diameter is greater than DN250, it is advisable to set it at 2.0 m/s to 2.5 m/s ； 9. The layout of the water intake wells should ensure that the water flow within the wells is in one direction, with a uniform flow velocity and without any vortices, and it should also be convenient for installation and construction ； 10. When the suction pipes and discharge pipes of fire pump systems pass through exterior walls, waterproof sleeves should be used ； When passing through walls and floors, the requirements of Clause 5, Article 12.3.19 of these specifications shall be met ； 11. When the suction pipe of the fire pump passes through the fire water tank, a flexible sleeve should be used ； When using rigid waterproof sleeves, a flexible joint should be installed on the water pump suction pipe, and the pipe diameter should not exceed DN150. 7 When there are two fire water supply sources and it is permitted for the fire pumps to draw water directly, the relevant regulations must be complied with. 1. Each fire water supply source shall meet the designed flow rate required for fire fighting purposes, as well as other water usage requirements that must be ensured during a fire ； 2. During a fire, the pressure in the outdoor water supply network, measured from the ground level, should not be less than 0.10 MPa ； 3. The head of the fire pump should be calculated based on the lowest water pressure in the outdoor water supply network, and the operating conditions of the fire pump should be verified using the highest water pressure in the outdoor water supply. Pressure gauges should be installed on the suction and discharge pipes of the fire pump. 8 The pressure gauges shall meet the specified requirements. 1. The maximum range of the pressure gauge on the outlet pipe of the fire pump shall not be less than 2 times its designed operating pressure, and shall not be less than 1.60 MPa ； 2. A vacuum gauge, pressure gauge, or vacuum-pressure gauge should be installed on the suction pipe of the fire pump. The maximum range of the pressure gauge should be determined based on the specific conditions of the project, but it should not be less than 0.70 MPa; the maximum range of the vacuum gauge should be -0.10 MPa ； 3. The diameter of the pressure gauge shall not be less than 100 mm. Pipes with a diameter of not less than 6 mm shall be used to connect to the inlet and outlet pipes of the fire pump, and shut-off valves shall be installed.