The mixed flow centrifugal pump has the function of self-priming, and there is no need to install a bottom valve in the pipeline. It is only necessary to ensure that there is a quantitative drainage in the pump body before work to have the function of "one-time drainage, life-long self-priming". Therefore, the piping system is simplified and the working conditions are improved. In order to ensure its normal operation, the correct installation before the official operation is also very critical. Let's share some installation experience.

The installation method of mixed flow centrifugal pump and the requirements to be met:

Since the liquid level of the suction pipeline of the self-priming pump is lower than that of the pump, during the suction process, the pipeline must be pumped into a negative pressure state before water can be sucked up. Therefore, the layout and installation of the suction pipeline should be in accordance with the following requirements:

The installation and laying of the suction pipe should avoid the formation of air pockets in the pipe.

In order to prevent air leakage in the suction pipe, the suction pipe must be completely sealed so that no air can be sucked in. The suction pipe of the self-priming pump is usually made of steel pipes, and the joints are connected by welding or flange.

The suction pipe is installed in the suction well, and the effective volume of the suction well should not be less than the pumping capacity of a larger pump for 5 minutes. In order to prevent the swirling flow from sucking air at the inlet of the suction pipe, it is required that the inlet should have a certain submerged depth, suspended height and certain spacing.

The design flow rate of the suction pipe of the mixed flow centrifugal pump is generally: when the diameter of the suction pipe is less than 250mm, the flow rate is 1.0-1.2m/s; when the diameter of the suction pipe is 250-1000mm, the flow rate is 1.2-1.6m/s; when the diameter of the suction pipe is larger than At 1000mm, the flow velocity is 1.5 to 2.0m/s.

When the water in the suction pipe contains dissolved gas, it will escape due to the reduction of the pressure in the pipe. If there is gas accumulation somewhere in the suction pipe, an air bag will be formed, which will affect the water-passing ability of the pipe. In severe cases, it will damage the house and absorb water.

In order to enable the pump to drain the gas in the suction pipe in time, the suction pipe should have a continuous upward slope along the direction of the water flow, and i≥0.005. The gas in the pipe is discharged from the top of the pump casing at the inlet of the pump.

When there are a lot of impurities in the water, a filter should be set under the bell mouth. When the water pump is artificially irrigated or the pump is started by using the water in the pressure pipeline. There should be a bottom valve on the suction pipe. The bottom valve is a check valve with a filter screen, which has a large resistance.

When the water level of the suction pool is higher than the axis of the pump, a gate valve should be set on the suction pipeline to facilitate the maintenance of the pump, and a separate suction pipe should be set for each self-priming pump. The length and fittings of the suction pipe should be minimized to reduce the head loss of the suction pipe.

When the number of mixed flow centrifugal pumps is 3 or more operating together, multiple pumps can be used to absorb water from the common suction main pipe, but the number is not less than two. When one fails, the remaining suction pipes can still pass the designed water volume. .

A gate valve should be set on the suction main pipe to facilitate switching and maintenance. When setting up a common suction pipe, the suction main pipe should be in a positive pressure state.

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