We have already talked about the difference between stable high-pressure water supply system and high-pressure, temporary high-pressure water supply system, characteristics, and the flow of the regulator pump, etc. This article would like to stress that the head of the regulator pump to determine and set pressure for colleagues to explore . The pressure pump head and pressure settings to determine the three cases to distinguish: (1) steady high-pressure fire water supply system, the pressure pump and fire pump share the pressure tank; (2) steady high-pressure fire water supply system , Pressure pump set air pressure tank; (3) steady high-pressure fire water supply system, there is no pressure regulator pump and water tank. As for the fire water supply system to replace the fire water tank to replace the pressure tank, and its water regulation capacity of 18m3, 12m3, 6m3, or "Sprinkler Systems Design Code" (GBJ45-85) revised version of the manuscript Specified 2.4m3, are not discussed in this article, the article refers to the pressure tank water regulation capacity of 450L and below the pressure tank. In the first case, when the pressure pump and fire main pump share the pressure tank, and the pressure tank is not used to replace the fire tank, only to meet the fire required before the start of fire main pump water and water pressure; and through the water level and pressure sensor to Control the start-stop pump and fire pump start-up, the pressure tank in the main three pressure settings, as shown in Figure 1. Figure 1 VX - water storage volume; VS - water volume regulator; VΔP - buffer water volume; V0 - water volume does not move; P0 - the starting pressure; P1 - the minimum working pressure; P2 - the highest Work pressure, fire extinguishing fire main pump start pressure; P3 - pressure water volume lower limit pressure, pressure regulator fire pump start pressure; P4 - pressure water volume upper limit pressure, pressure regulator fire pump stop pressure; h0 - starting water level ; H1 - fire water storage volume lower limit water level; h2 - fire water storage volume upper limit water level; h3 - pressure water volume lower limit water level; h4 - pressure water volume upper limit water level. P2 is the starting pressure of the fire main pump, P3 is the starting pressure of the stabilizing pump, P4 is the pressure of stopping the pump of the stabilizing pump, according to the experience of China's relevant design institute P3-P20.02MPa, P4-P30.05MPa. The water levels corresponding to the pressure values ​​of P2, P3 and P4 are h2, h3 and h4. h2 water level line under the water regulation volume, according to "Code for fire protection of high-rise buildings," the provisions of 450L, h2 ~ h3 section of the water volume of buffer water volume, h3 ~ h4 section of the volume of water for the regulator volume. In this case, the pressure setting of the pressure regulating pump is P3 and P4, and P3 is the lower pressure setting value of the pressure regulating pump, that is, the starting pressure of the pressure regulating pump; P4 is the upper limit of the pressure setting of the pressure regulating pump, that is, Pump stop pump pressure. P3 and P4 are greater than P2, greater than the head of fire main pump. The opinion of the domestic technical community is consistent with the relative relationship of the above pressure setpoints and the relevant requirements have been incorporated into the relevant provisions of the Code of Practice for Design of Pneumatic Water Supply (CECS 76:95) (see specification item 4.3.4). If you want to explore, but also limited to P3 and P4 pressure set value higher than P2 how much the problem. The second case when the system is equipped with a pressure tank, and the pressure tank does not store the fire required before starting the fire pump water, pressure tank settings, its only purpose is to: (1) control the start and stop pump ; (2) to ease the regulator pump start and stop too often; (3) buffer due to stop pumping caused by water hammer on the system pressure shock. In this case, the conventional approach is to start the pressure regulator pump pressure, that is, the pressure lower limit slightly higher than the head of the fire pump, pump stop pump pressure, that is, the upper limit of pressure by the pressure tank working pressure ratio, that is Air pressure tank to adjust the volume to determine, but also determined by empirical coefficient values, the method is similar to the first case, shown in Figure 2. The water levels corresponding to P3 and P4 are h3 and h4, and the water volume in the area between h3 and h4 is the buffered water volume. There are also fire main pump start pressure value set in the pressure tank, and if so, Figure 2 is converted into the form of Figure 1. Note: Figure 2, the letter meaning the same way in Figure 1 has been questioned for a long time without permission, is based on the following reasons: (1) The function of the pump is to stabilize the water pressure in the fire network to understand the existence of water pressure One-sidedness and surface. (2) Think fire pumps, including fire main pumps and booster pumps, do not need to account for efficiency and energy consumption as life pumps do. At the same time for the sake of stability, that the pump head high, high pressure pipe will not be harmful, good for fire fighting. (3) According to the fire design flow calculation main fire pump head, then calculate the pressure pump set pressure value and lift, more convenient. (4) There is no study on the technical aspects of fire protection. However, the situation is changing. With the increasing emphasis on steady-pressured water supply systems, some new problems have arisen due to the application of a centralized and stable high-pressure water supply system: (1) high pump head and high pipeline pressure are not the case in some cases Good thing. Long-term operation of the pipe network under high pressure, easy to aggravate the leakage, causing pipe fittings displacement and other issues. (2) The number of main fire pump start-up less, you can not need to count as life pump efficiency and energy consumption, and pump the situation is different, start and stop frequently, without regard to pump efficiency and energy consumption is not appropriate . Therefore, it is necessary to meet the most unfavorable fire extinguishing facilities fire water pressure and water requirements under the premise of determining the pump lift and pressure settings. When the fire main pump work: fire design flow Qs; the most unfavorable fire extinguishing facilities when the required water pressure Hx; the most unfavorable fire extinguishing facilities and fire main pump elevation difference ΔΗ; pipe network through the fire design flow The required head loss is Hy; the local head loss required by the design of the network for fire fighting is Hj, then the head of the fire main pump is: H = Hx + ΔH + Hy + Hj (1) When the pump works: The most unfavorable place fire extinguishing facilities in the fire required when the water pressure is still Hx; the most unfavorable place fire extinguishing facilities and stabilizing pump elevation difference ΔH ', when the pump is low Laying, and fire main pump in the fire pump room, ΔΗ 'and ΔH values ​​quite close; pipe network through the steady flow required head pressure loss is Hy'; pipe network through the regulator required for the local flow The head loss is Hj '; then the head of the booster pump is: H' = Hx + ΔH '+ Hy' + Hj '(2) Compare Hx = Hx, ΔHΔΗ'. Head loss along the way and local head loss are determined by the flow rate, the pump flow is much smaller than the fire main pump flow, so Hy '"Hy, Hj'" Hj, or H'H. The conclusion is that H '≠H, to meet the most unfavorable fire extinguishing facilities on the premise of fire water pressure, the pump lift head does not equal to the head of the main fire pump, pump head can be lower than the head of the main fire pump. This conclusion will bring designers several serious concerns: (1) not understand. Generally considered the main fire pump head is the pressure of fire, but do not understand the different design flow allows for different fire pressures. Therefore, on the surface, it is not easy to understand that the pressure head of the pump is lower than the head of the fire main pump, but in essence, both of them are premised on meeting the water pressure requirements of fire water for the most unfavorable fire extinguishing facilities. The difference is that the fire main pump flow, regulator pump flow is small, even if all in order to meet the same place, the same purpose, the same purpose of hydraulic pressure requirements, and because of fire design flow and the difference between the value of the constant flow rate, so that the two pumps lift Different. However, even if the two pumps have different heads, there is no problem in terms of ensuring the fire hydrant pressure requirements. (2) There are doubts about the operation of the pipe network. In actual operation, when the pressure tank is pressure P4 and the highest water level h4, the pressure regulating pump stops pumping. When there is leakage in the pipe network and the water level drops to h3, Pump start; pump start-up, pressure tank water level rise, when the rise to h4, the pressure pump stop.gunsq1 li {display: block; float: Pumps, Spray Pumps, Sewage Pumps [Buy] Bearing Accessories [Buy] Air Lock Valve [Buy] Signal Amplifier [Buy] Valve [Buy] Centrifugal Pump [Buy] Vertical Multistage Pump [Buy] Fuel Tank [Buy] Inverter motor Previous: The type of hot oil pump Next: Solenoid valve technology
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