Diameter change on the pipe
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We need to install several water pumps and slurry pumps here. Reducing diameters are required at the inlet of the pumps and at the outlet of the tank. Should we use eccentric reducing diameters or concentric reducing diameters? What is the difference between these two types of reducing diameters when applied to the pump inlet? I would appreciate some guidance from an expert.
When using eccentric tees with the elbows directed downward, the top of the reducing pipe remains level； When the elbow is turned upward, the top of the reducer is level, with drainage added at the lowest point. At the inlet of pumps used to convey solid particles or slurries, the eccentric reducer should be installed at a low level. From: Quick Reference Manual for the Installation Design of Petrochemical Pipelines.
It mainly depends on whether your inlet and outlet are vertical or horizontal; if they are vertical, use concentric fittings, while if they are horizontal, use eccentric tees. As for whether the tops or bottoms should be aligned, you can refer to http://bbs.hcbbs.com/thread-77476-1-1.html
The main purpose is to prevent the formation of air pockets; it depends on the specific conditions at the site, as the two people upstairs explained very clearly.
The pump inlet is usually an eccentric reducer; if the inlet pipeline comes from above, a bottom-flat reducer is used, while if it comes from below, a top-flat reducer is used. In most cases, the pump outlet pipe is a vertical pipe, so concentric reducers are sufficient.
As an additional note, the size adapters are generally installed near the pump’s inlet and outlet ports; if they can be welded directly to the flanges, that’s what is done. If it’s a flat-face flange and direct welding isn’t possible, then a short section of pipe is used as an adapter.
LZ should take a look at the piping connected to the pump. Classmate LS said that tees are usually installed near the pump outlet; I think this is mainly because there is usually very little space in the area where the pump’s piping is located, which forces such a solution. If there is space in the pump piping area of LZ, try to leave a straight section of pipe between the elbow and the pump inlet to stabilize the flow pattern.
I agree with the view above; for centrifugal pumps with axial suction, in order to prevent flow deviation, vortex currents, and air blockages from occurring after the liquid enters the pump, which could lead to vibrations and noise and affect the pump’s head and power output, there should be a straight pipe section at the pump’s inlet that is at least 3 times the diameter of the pipe.