1. How many meters is the suction stroke of a centrifugal pump?
The pump has an important performance parameter called the suction stroke. The suction stroke is also called “maximum self-priming height” (it can also be understood as “the degree of self-priming”), and the unit is m, which is calculated by subtracting the NPSH of the pump from the local atmospheric pressure, and then subtracting the loss along the suction pipe and The vaporization pressure of the water temperature determines the vertical distance between the pumping port and the liquid surface to be pumped. Any pump has a suction stroke, and the size is different. So in the commonly used centrifugal pumps, what is the maximum suction stroke of the centrifugal pump?
The maximum suction lift of a centrifugal pump is mostly about 8 meters of water column. The theoretical value of the suction head is 10 meters, but in practice, due to accuracy, efficiency and other reasons, it cannot reach this number, so the installation height of the pump must be below this number. In practical applications, the suction lift of centrifugal pumps is up to 8 meters. However, the self-priming height of the general self-priming pump is only 3-5 meters, and other centrifugal pumps are similar to this height.
Second, how to improve the suction lift of a pipeline centrifugal pump
Many people sometimes need a pump with a large suction lift according to their actual working conditions when choosing a pump type. Centrifugal pump, then how to correctly improve the suction lift of the pipeline centrifugal pump?
1. Because the pipeline centrifugal pump does not have a water storage chamber and the mechanical seal has no independent oil chamber, the centrifugal pump must install a bottom valve in order to obtain a suction lift to ensure that the mechanical seal is immersed in the liquid medium.
2. Exhaust. Gas in the inlet pipeline is an important factor for the centrifugal pump not to be filled with water. There is a vent screw on the outlet flange of the centrifugal pump in the pipeline. When starting the centrifugal pump, open the vent screw until the pump is filled with water and then closed.
3. A vacuum pump is installed in the outlet pipeline. The negative pressure capacity of the vacuum pump is incomparable with other pumps. The self-priming pump needs 3~5min to discharge the air and the vacuum pump only needs less than 30S. Installing a water ring vacuum pump on the outlet pipeline can effectively shorten the self-priming time of the centrifugal pump and improve the suction stroke of the pipeline centrifugal pump. Vacuum assist systems, which have been successfully used today, are convenient and inexpensive. Reduce the medium temperature.
4. The suction stroke of the pipeline centrifugal pump is affected by the temperature of the medium. If the liquid temperature is too high, serious cavitation will occur, and the impeller will be scrapped within a certain period of time. Research shows that reducing the liquid temperature can effectively improve the Suction lift of a centrifugal pump.
5. Irrigation. When the pipeline centrifugal pump starts, injecting liquid into the pump body is equivalent to forming a seal for the impeller, the gas flows in one direction, and the exhaust speed is faster.
