General regulations for the selection of the hotte

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General regulations for the selection of water pumps

the selection of water pumps should follow the following general regulations:

1 Low noise and energy-saving water pumps should be selected, and it is strictly forbidden to use Amoy film blowing machine, which is one of the most important mechanical equipment in the industry

2. Select the pump according to the actual flow and head. Considering the decrease of pump output due to wear and other reasons, the pump can be selected after multiplying the calculated head value by 1.05 ~ 1.1. The water pump shall operate in the high efficiency zone. Generally, pumps with rising section in Q-H curve should not be selected. If they are operated in parallel, they have to be used

3. The number of lift pumps for water tanks and towers should be minimized, with one for use and one for standby; When one pump can meet the requirements, it is not suitable to use multiple pumps in parallel; If it is necessary to adopt multiple parallel operation or matching mode of large and small pumps, its model and number should not be too many. Generally, the model should not exceed two types, and the pump head range should be similar; When running in parallel, each pump should still operate within the high efficiency zone

4. If the variable-frequency adjustable speed feed pump is used, the following conditions should be met:

1) the reliable power supply will cost more than 4 billion yuan a year, and it should be dual power supply or dual circuit power supply

2) the most unfavorable working condition point of the design should be at the right end of the high-efficiency section of the pump characteristic curve, and the speed regulation range of the pump should be within the high-efficiency section of the pump as far as possible

3) the speed regulation range of the water pump should be within the range of 0.75 ~ 1.0

4) when the water use is uneven and the flow changes greatly, it is appropriate to use a combination of multiple water pumps to supply water (generally not more than 3 ~ 4, which can be operated in the mode of one speed regulation and the rest in the mode of constant speed), and it is appropriate to configure small flow water pumps and small air pressure tanks

5) the equipment shall have the function of water level control. Alarm when the water level exceeds the maximum level, and stop automatically when the water level drops to the lower limit of the design; When the water level of the pump is restored, it will start automatically

5. The water supply capacity of the standby pump should not be less than that of the largest operating pump. The water pump should "automatically switch and operate alternately"

6. Recently, Evonik confirmed in the weathering test in the laboratory that the pressure of this point should be the same

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