Most fire-fighting water supplies for fire-fighting water require fire-fighting pumps for pressurization to meet the pressure and quantity of water required for fire extinguishing. Pump failure due to improper installation and maintenance will inevitably affect firefighting and rescue, resulting in unnecessary losses. Here, the nature pump industry talks about personal understanding of several fire pump problems encountered in the work.

1. Is it necessary to set up a special multi-level fire pump in a multi-storey building?

Regulation 8.3.3 of the Code for the Prevention of Fire Protection of Building Design (hereinafter referred to as the “Building Regulations”) stipulates: “For fire protection tanks or water pressure tanks or water towers, the buildings that set up temporary high-pressure water supply systems shall be provided.” In accordance with this provision, firefighting water tanks should be installed in buildings that set up temporary high-pressure fire-fighting water supply systems. Such buildings are mostly four-storey and five-storey multi-storey buildings, and the pressure of the municipal pipe network is generally 20 to 30 meters. In order to meet the needs of the most unfavorable fire hydrant to fill the water column, such buildings should also be equipped with fire-fighting pumps. However, the purpose of setting up indoor fire hydrant systems in multi-storey buildings is only to save the initial fire, and a large number of fire-fighting tasks also depend on the urban fire brigade. Therefore, setting up multi-stage fire pumps is inevitably somewhat wasteful. For such buildings, I do not know whether they can learn to use high-rise buildings to install booster facilities on the outlet pipe of fire tanks. In the water outlet pipes of fire tanks, there is a button that can pass through the fire box or the flow indicator on the outlet pipe of the fire tank. Booster pumps started to meet the need to enrich the water column. In this way, the booster pump is installed on the roof, is a light-load start, and has a fast start-up speed, which should be beneficial to the initial fire.

Under the premise that the municipal pipe network can meet the indoor and outdoor fire-fighting water consumption, I wonder whether it can be considered whether to set up a fire pump according to the different uses of the building. That is, in the factory area and large public buildings, it is advisable to set up a fire pump so that it has a certain self-rescue capability. In a typical residential building, it is allowed to have no fire pump. In case of fire, the fire engine uses a water pump adapter to spray water outdoors. Fire extinguishing, after all, even if a fire pump is installed in a residential building, residents may not be able to use it properly.

Second, multi-stage fire pump performance and test requirements

Fire pumps have higher performance requirements than domestic pumps and production pumps, but China's current specifications do not make specific requirements for the performance and testing requirements of fire pumps. This makes fire pumps useless when selected. There have been many problems. The performance requirements of the US NFPA20 for fire pumps are: the maximum flow of the fire pump should be 150% of the design value, the lift should not be less than 65% of the head of the selected working point, and the lift when the pump is turned off should not be greater than 140% of the head of the selected working point. The regulated pump flow is 1-2L/S, and the lift is 1.1-1.2 times the lift of the fire pump. At the same time, it is stipulated that a flow meter for measurement should be installed on the fire pump outlet pipe. The flow meter should be able to test 175% of the selected flow rate of the pump. The fire pump should be equipped with a pressure gauge with a diameter greater than 89 mm on the outlet pipe. It is suggested that the customs authorities refer to US standards to provide more targeted and specific requirements for the design and selection of fire pumps in China so that they can be used in the selection and testing of fire pumps.

Third, the laying of the pump circuit

In many design drawings, it is found that the power supply and distribution lines and control circuits of the multi-stage fire pump are protected by PVC pipes and are routed from the ceiling. The author thinks this routing method is not proper. Although the "Building Regulations" only requires that the distribution line of fire-fighting electrical equipment be exposed to metal pipes when exposed, there is no requirement to protect the metal pipes when concealed, but the "Civil Design Code for Civil Buildings" (hereinafter referred to as "the People's Regulations") 24.8. 5 requirements: fire-fighting linkage control, automatic fire extinguishing control and other lines should be used flame-retardant cable through the pipe in the non-burning body structure, the thickness of the protective layer is not less than 3cm, when it must be applied, it should be on the metal pipe Take fire prevention measures. Regulation 8.2.2 of the "Automatic Fire Alarm System Design Specification" (hereinafter referred to as the "Automatic Alarm Code") also provides corresponding provisions. We know that fire-fighting pumps still have a role to play for a period of time after a fire has occurred to complete the fire fighting of building fires. Therefore, during this time, the safety of the pump circuit must still be guaranteed. For a long distance between the power distribution room and the electric shaft, if the capacity of the fire extinguishing equipment is large and the line cannot be concealed, it may be laid in the ceiling after effective fire prevention measures are taken. In this case, the fireproof tank box should be avoided because the ceiling is also a fire-prone area. The line laid in the ceiling is not safe in fire, and the tank box can only prevent the external combustion from damaging the line and can not prevent the line in the box. Fire caused by its own fault. It is suggested that fire-fighting pumps and other important fire-fighting equipment should be powered by fire-resistant cables to ensure that they can continue to work without being affected for a certain period of time in the event of a fire.

Fourth, multi-level fire pump should be set overload protection

Multi-stage fire pump is an important equipment for fire fighting and rescue, and plays an extremely important role in fire extinguishing. According to our customary thinking, overload protection should be provided for any important equipment. However, Article 8.6.3.5 and Article 10.2.2.4 (3) of the "Public Regulations" stipulate that: "For sudden power failure, it will lead to a distribution line that is greater than the loss caused by overloading. It should not be installed to cut off the circuit. Load protection appliances (such as the fire pump water supply line), but should be equipped with overload alarm appliances. In accordance with this provision, fire-fighting pumps should not be equipped with overload protection cut-off devices. This is mainly to take into account the need to ensure fire water use at the time of a fire, because line and equipment losses due to pump overload may be insignificant compared to fire losses. However, in the actual project, even in the standard construction atlas, including the current water pump electrical diagram described in the current university textbooks, the fire pump circuit is still added to the overload protection cut-off electrical appliances, such as "atlas of electrical installation engineering" JD13- Page 318, "High-Voltage Building Fire Protection System Full-Voltage Operation Fire-Fighting Pump Control Unit Diagram (II)". This obviously does not meet the specification requirements.

Fifth, multi-level fire pump control

1) Control voltage. According to Article 24.6.2.1 of the "Public Regulations", the control circuit for the starting fire pump in the fire hydrant box and the control circuit for the start-up pump signal light shall use a safety voltage of 50 V or less. Clause 24.9.11 stipulates that the DC operation power supply voltage of the fire linkage device should be 24V. This is mainly to prevent the use of fire hydrant, the overflow of water causing the fire hydrant box and water and water guns to injure the firefighters. smell). However, in the actual construction and some reference materials, the power supply voltage of the fire hydrant button is still connected to the AC 220V. Such an error was made on the same page as the previously mentioned Atlas. 2) Start control. There are three places where fire hydrant pumps can be controlled to start.

1 According to the "Building Regulations" and "High-rise Civil Building Design Fire Prevention Code" requirements, the fire hydrant box at the indoor start directly. 2 According to the requirements of "automatic alarm specification", control at the fire control room. 3 Control near the hydrant pump in the pump room. This should correctly handle the following two issues: First, the priority of control of fire control rooms, fire hydrant buttons, and fire pump rooms should be properly determined. In general, it should be based on long-distance operations in the fire control room. However, due to the lack of a clear guideline for long-distance operation by relevant departments, there are many practical practices in engineering, and the rationality and operability are inevitably mixed. Some simply turn on/off the pump button and/or connect it to the manual start/stop pump button of the secondary circuit. Some of them simply remove the thermal relay. Most of them are set on the pump room control cabinet by manual/automatic switch. Usually, Put in an automatic position. We think that all these methods are flawed. Comrade Song Gaofei proposed in his article “Discussion on the Design of Long-distance Operation of Fire Pumps” that the long-distance operation relay contact point crossed over the transfer switch part and be directly connected to the coil circuit of the main contactor of the fire pump to directly start the fire pump. We believe that the idea is good. It not only solves the problem of direct start-up, but also facilitates unified monitoring in the control room. It also satisfies the need for long-distance starting of the fire pump when the pump house control cabinet is in any state. The second is to determine the fire pump to start what kind of way. In order to put the fire fighting equipment into work as soon as possible to reduce the fire damage, taking into account that most of the fire-fighting loads have been cut off at the time of fire, the fire-fighting pump should give priority to full-pressure direct start.

Fault control. According to the requirements of Article 4.2.1 of the “Automatic Warning Regulations”, the fire control room shall be able to display the failure status of the fire fighting equipment. Due to technical problems, the fire control of the simple fault signal such as power failure can be displayed, while the failure signal of other fault signals such as the fire pump is not clearly stated in the "Automatic alarm specification" and "Public Regulations". This often avoids this and affects the correct detection of equipment faults in the control room.

Use the manual alarm button instead of the hydrant button to start the pump. Replace the fire hydrant button with the fire hydrant at the hydrant button to start the pump is more popular in the actual project, the project uses double contact buttons, a contact for hand reporting, the alarm signal is sent to the fire alarm controller, another contact for Kai For the pump button, the pump signal is sent to the control room to start the pump through the double switch box. However, according to Article 8.6.2 (9) of the "Building Regulations" and Article 7.4.6.7 of the "High Regulations": Each fire hydrant should be provided with a button to directly activate the fire pump. The manual button push pump is to send the fire signal back to the alarm linkage controller. After confirmation, the controller starts the fire pump and does not directly start the fire pump. Moreover, this alternative method places higher demands on the automatic alarm system. At present, due to the high false alarm rate and operating costs of automatic alarm systems, some buildings’ automatic alarm systems are often sickly or even unopened, making it difficult to play their due role. Therefore, we believe that it is still not advisable to use a fire hydrant instead of a fire hydrant button with a hand report.

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