Eccentric stub end
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This post was last edited by leo_0088 on 2011-1-24 at 22:08. There is a multi-stage pump for boiler feedwater in the workshop; both the inlet and outlet pipes are vertical, with the inlet pipe having a diameter of DN50. Now, it is necessary to change the diameter of the inlet pipe to DN100. The pump manufacturer recommends using eccentric tees. I would like to ask those who have experience in this area: is it really necessary to use eccentric tees? If so, are there any specific requirements regarding their installation? Additional note: Deoxygenated water is used to provide the inlet pressure for the boiler feed pump through a pressure difference; since the deaerator is located at a lower level, cavitation occurs in the pump, which is why an increase in the diameter of the inlet pipe was adopted. The inlet pipe is vertical, not horizontal.
It depends on whether your impeller is mounted vertically or horizontally. According to what you said, it should be mounted vertically; in that case, cavitation generally does not occur, so a concentric inlet can be used. If it is mounted horizontally, then an eccentric inlet is necessary
This post was last edited by hcwang12345 on 2011-1-24 at 19:58. According to you, since the boiler feed pump provides positive pressure for water supply, the gas in the pipes can return smoothly to the high-level water tank (or deaerator). Therefore, it doesn’t matter whether it is installed horizontally or vertically, and using concentric reducers is acceptable in such cases. If the water is supplied under negative pressure and the installation is horizontal, then there are requirements regarding the orientation of the eccentricity – the straight side should be at the top.
If the inlet is horizontal, eccentric tees with the flat ends facing upward must be used; if it is vertical, concentric tees are used, unless other circumstances apply!
The last edit to this post was made by diwu0205 on 2011-1-25 at 17:08. The imported pipeline mentioned by the original poster is vertical, but the section connected to the water pump is horizontal, right? The eccentric large and small ends are installed with a flat top.
Reply to 5# moliang2 Thank you! ! ! The pump inlet has always been vertical.
This post was last edited by diwu0205 on 2011-1-25 at 17:10. Reply to 6# leo_0088: There’s no need to use an eccentric design; it’s pointless.
For piping, if the pump inlet is perfectly vertical, concentric reducers can be used; there is little advantage to using eccentric reducers.
Reply to 4# mm189: For pipelines that feed pumps horizontally, it is necessary to determine the flow direction of the medium in order to decide the upper and lower positions of the flat ends of the elbows. If the medium flows from a lower position to a higher one and enters the pump, then a top-flat eccentric reducer should be selected ； If the medium flows into the pump from a higher position to a lower one, then an eccentricity with a flat bottom should be selected.
This post was last edited by Bagua Lu on 2011-1-25 at 15:58. Since the pump inlet pipe is also vertical, it is advisable to use concentric reducers as much as possible; they are inexpensive, result in low resistance, and are also aesthetically pleasing. Explain the situation to the manufacturer, and they will agree.