When purchasing a pump, can the user’s requirements for flow rate and head be met?

It’s possible in theory. But everything has its logic. After a pump is designed, there is the issue of an efficiency point.

This post was last edited by 3983596_FPPZ on 2019-3-31 09:15. Does your operating condition change? The flow head at the performance level you specified is met; the pump manufacturer is responsible for cutting the impeller according to the parameters provided during ordering. If you are looking for a range of values, it must be specified at the time of ordering. If any of the requirements are not met, your company will not enter into a sales contract with the manufacturer. Everything is subject to the provisions of the technical agreement or contract, unless additional requirements are put forward after ordering – in that case, the responsible party should take responsibility for it. .

Pump manufacturers cut impellers in order to expand the range of specifications for their products, but they don’t do so specifically for a particular customer?

This post was last edited by 3983596_FPPZ on 2019-4-1 07:47. It’s not what you think; the pump manufacturer cuts the impeller to the appropriate size based on the actual operating conditions. They won’t send you a pump with an impeller of the maximum diameter for you to cut yourself, as that would be equivalent to selling you a semi-finished pump. The cut impeller expands the performance range of the pump, reduces its hydraulic specifications, increases the options available during selection, and lowers mold costs. However, for a specific operating condition, the pump manufacturer must be responsible for ensuring proper cutting so that the requirements of those operating conditions are met; otherwise, the large impeller will cause various performance issues and overload the motor – can such a pump still be used?

For all centrifugal pumps whose impellers have been cut, letters such as A, B, C, D, etc. are indicated after their model numbers, indicating that the impeller has undergone the first cut, the second cut, and so on. But you see, in practice, most pump models don’t have letters at the end of them – they haven’t been cut, right?

ABCD indicates the first, second, third, and fourth cuts – in other words, the size at which cutting occurs. However: 1. In many cases, the cutting takes place at the midpoint between the two designated letters, or away from the designed point; as a result, it is not possible to accurately determine to what extent the cutting has taken place or which cut it corresponds to. Therefore, letters are not used to represent this； 2. Some pump manufacturers don’t bother to determine whether the impeller has been cut at the ABCD points; for the sake of easier communication and management, they simplify the pump models, so even when the impeller has been cut, it is referred to as if it hasn’t been cut. Whether cut or not, they are referred to by the name of the original pump; the dimensions after cutting are recorded in other documents for tracking purposes. In both of these cases, the enforcement of the rules for cutting ABCD is weakened; different manufacturers adopt different approaches, so it’s best not to be too dogmatic

If efficiency and operating current are not a concern, it’s theoretically feasible, but no one buys pumps in that way

After obtaining your series of data, an NS specific speed is calculated; a model is selected based on this specific speed, and then an appropriate impeller diameter is chosen using the nD value along with the data obtained through proportional conversion. If existing molds are available, the part can be manufactured using them; otherwise, it can still be produced without creating new molds

This statement is incorrect; the impeller of a centrifugal pump can indeed be machined, but it must do so within the specified range