Broken shaft problem in variable-frequency pumps
Thread Content
This post was last edited by XinYouMengHu on 2015-10-14 at 11:02. I would like to ask everyone the following: 1. Since I work in testing, the operating conditions often change; will the pump operating at a low flow rate with variable frequency for an extended period of time cause shaft breakage? 2. In cases of extremely high flow rates, shouldn’t vertical pipe pumps be avoided in favor of horizontal ones? What are the benefits? What about the vibration balance stability? What about noise? 3. What is an appropriate lower limit for pump frequency conversion for testing purposes?
Generally, if a centrifugal pump is not operated at its designed operating point, the impeller and its main shaft will be subjected to significant radial forces, which reduces the service life of the rotor components. Under normal circumstances, the minimum frequency required for an inverter is not less than 10 Hz; however, different manufacturers may have different requirements.
Most pumps have a minimum flow rate point; they cannot operate below this level, as doing so can lead to equipment failure over time
1. Since it is used for testing purposes, the operating conditions often change. Will the pump operating at a low flow rate with variable frequency for an extended period of time cause shaft breakage? This is possible; it needs to be calculated based on the pump outlet pressure and flow at low speeds. In some special circumstances. For example, compared to situations where the rotational speed and flow rate are extremely high. 2. In cases of extremely high flow rates, shouldn’t vertical pipe pumps be avoided in favor of horizontal ones? What are the benefits? What about the vibration balance stability? What about noise? I’m not clear what you mean by ‘extra-large data volume’. Horizontal pumps and vertical pipeline pumps each have their advantages and disadvantages, with the specific ones depending on your application conditions. Generally speaking, it’s pointless to discuss advantages and disadvantages (just like debating whether a wealthy man or a good-looking man is more suitable for marriage). In terms of vibration balance, horizontal pumps generally exhibit better vibration performance. 3. What is an appropriate lower limit for pump frequency conversion for testing purposes? If the frequency is too low, the shaft is prone to breaking.
This post was last edited by XinYouMengHu on 2015-10-15 08:48. Hello, at a flow rate of 600 m3/h and a power output of 90 KW, will vertical pumps cause significant vibration? Is it necessary to use horizontal pumps instead? What about 1800 m3/h?
It is recommended to choose a horizontal pump for easier installation and maintenance.
I have some time today, so I took a look at API 610 to add something to my previous response. As mentioned in the previous response, horizontal pumps exhibit better vibration performance compared to vertical pumps, based on Tables 7 and 8 of API 610, Version 10. At roughly the same load, the requirement for vertical pumps is 5 mm/s RMS, whereas for horizontal pumps it is 3.0 mm/s RMS. Returning to your question from 8:46 a.m. yesterday: In my opinion, the vibration behavior of vertical pumps mainly depends on the length of the drive shaft. And the length of this drive shaft determines the limitation on the positive net suction head (NPSHa) when a horizontal pump is used. In other words, under certain operating conditions, using a vertical pump may be the only option available. Things to consider if you are switching from a vertical pump to a horizontal pump. Just in terms of maintenance, it is undoubtedly much easier to maintain horizontal pumps than vertical pumps. However, in terms of operation, vertical pumps may have some advantages over horizontal pumps.