Questions about tandem pumps
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In order to save money, we connected two centrifugal pumps (50YII-60×2) in series. We have been using them for more than half a year now. Is there any harm in doing this?
.... Let’s analyze the specific problem in detail. This requires understanding the installation method of the poster, the entire pipeline layout, the properties of the liquid, etc., in order to have a detailed analysis: handshake
The outlet of pump 1# is connected to the inlet of pump 2#, and the medium is diesel. After series connection, the pressure rises from about 1.0MPa to about 1.4MPa.
The performance curve of centrifugal pumps is relatively flat. Parallel operation can increase the flow rate and head more than series operation. However, in actual engineering applications, series operation is almost never used.
It may have a certain impact on the mechanical aspects such as the sealing of the latter pump, because the pumps are the same, but the inlet pressure of the latter pump is its original design outlet pressure. The outlet pressure must be higher.
The main issue is safety. When two pumps are connected in series, the total outlet pressure rises significantly. Whether the pump body and outlet pipeline of the second pump can withstand the corresponding pressure, after all, exceeds the design pressure.
As long as the head of the pump is not very high, it will generally not exceed the design pressure of the pump and pipelines. In actual production, due to process changes or other reasons, when the original pump head is insufficient (but the flow rate can remain unchanged), as long as the final outlet pressure does not exceed the design pressure of the pump and related pipelines, the two pumps can be used in series. If a backup pump is really needed, another pump with a higher head can be purchased. Since the pressure only increases by 0.4MPa, it will not have much impact on the pump.
I have never seen two pumps used in series. Doing so may reduce operational stability, for example if a failure of one pump results in abnormal operating conditions of the other pump.
Personally, I feel that there is no need to use a series of pumps. After all, it is a centrifugal pump.
Of course you can buy a new pump if you have money, but you can only use it this way when you have no money or in emergencies. It costs money to buy a new pump, and the two old pumps are useless. It takes at least 3 months from the time of purchase, installation and operation. Those who work don't have to think about it, but those who are bosses will know what to do once they have calculated it. :lol
Series connection should be undesirable. Sometimes in order to achieve flow, parallel connection can be used. I think series connection can only cause a loss of pump efficiency and should be superfluous.