Layout and installation specifications for suction pipes of self-priming sewage pumps

Layout and installation specifications for suction pipes of self-priming sewage pumps

The self-priming sewage pump water suction pipe has a lower liquid level than the pump. The self-priming sewage pump must first pump 

the pipe to a negative pressure state before it can be suctioned. Therefore, in the arrangement and installation of the self-priming pump 

water suction pipe, the self-priming pump water suction pipe should be arranged and installed in accordance with the following self-priming 

pump installation specifications:

(1) In order to prevent air leakage from the suction pipe of the self-priming sewage pump, the suction pipe must be completely sealed and not

 be sucked in. The water suction pipe of the self-priming pump usually uses steel pipes, and the joints are connected by welding or flange.

(2) When the water in the water suction pipe contains dissolved gas, it will escape due to the decrease in the pressure in the pipe. If gas accumulates 

somewhere in the water suction pipe, an airbag will form, affecting the water passing capacity of the pipe. In severe cases, it will damage the water 

absorption of the real home. In order to enable the water pump to discharge the gas in the water suction pipe in time. The suction pipe should have

 a slope that rises continuously along the water flow. And i≥0.005. The gas in the tube is discharged from the top of the pump housing at the inlet of the water pump.

(3) The installation and laying of the suction pipe of the self-priming sewage pump should avoid airbags in the pipeline. The following describes several 

correct and incorrect installation methods for suction pipes.

(4) The suction pipe is installed in the suction well, and the effective volume of the suction well should not be less than the maximum water pumping

 capacity of one pump in 5 minutes. In order to prevent swirl flow at the inlet of the suction pipe to absorb air. Therefore, imports are required to have

 a certain submersion depth, suspension height and a certain spacing. Specific size requirements are:

1) The water depth of the inlet of the suction pipe of the self-priming sewage pump is ≥0.5~1m, otherwise a horizontal partition should be installed.

2) A flare should be installed at the inlet of the suction pipe of the self-priming sewage pump to make the water flow in the inlet of the suction pipe

 stable and reduce losses. The diameter of the large head of the flare mouth D—1.3～1.5d, (d is the diameter of the suction pipe); the height of the

 flare mouth is (3.5～7)(D--d).

3) The distance h1 (suspended height) between the lower edge of the trumpet mouth from the bottom of the well should be greater than 0.8D.

4) The distance between the outer edge of the trumpet mouth and the outer wall L1 must not be less than (0.75-1)D.

5) The distance L2 between the trumpets shall not be less than (1.5---2)D.

(5) Each self-priming sewage pump should be equipped with a separate suction pipe. And the length of the suction pipe and the fittings should be 

minimized to reduce the loss of the suction pipe head. When the number of self-priming pumps is 3 or more, multiple water pumps can be used to 

absorb water from the shared water suction pipe, but the number is no less than two, and one fails. The remaining suction pipes can still pass through

 the designed water volume. As shown in Figure 6-16, a gate valve should be installed on the water suction main pipe to facilitate switching and maintenance.

 When setting up a shared suction pipe, the water suction pipe should be in a positive pressure state.

(6) When the water level of the suction tank is higher than the axis of the water pump, a gate valve should be installed on the water suction pipe to

 facilitate the maintenance of the water pump.

(7) When there are a lot of impurities in the water, a filter should be installed under the trumpet. When the water pump is started by artificial watering or 

using water filling pumps in pressure pipes. A bottom valve should be installed on the suction pipe. The bottom valve is a check valve with a filter screen 

and has a large resistance. There are two types of bottom valves: underwater and overwater. The underwater bottom valve is installed at the end of the

 suction pipe. Because it is easy to damage, it needs to be repaired frequently, which causes inconvenience to use. Currently, water-mounted bottom valves 

are mostly used, as shown in Figure 6-17. It has the characteristics of good use effect and easy installation and maintenance. When using a water-type 

bottom valve, the horizontal section of the suction pipe should be made to have sufficient length to ensure that sufficient vacuum value can be generated 

in the pipeline when the water pump is started.

(8) The design flow rate of the suction pipe of the self-priming sewage 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 between 250~1000mm, the flow rate is between 1.2~1.6m/s; when the diameter of the

 suction pipe is greater than 1000mm, the flow rate is between 1.5~2.0m/s.