When buying a pump, the power value calculated by the manufacturer’s sizing seems incorrect – what should I do?

Provide your process parameters, and the manufacturer will select the appropriate model! Write it into the agreement!

This post was last edited by 3983596_FPPZ on 2019-3-23 09:24. It is the responsibility of the purchaser to provide accurate information regarding operating conditions, properties of the medium, and process parameters; any consequences resulting from inaccurate or incorrect information provided are the purchaser’s own responsibility； Based on the information provided by the purchaser, the pump manufacturer is responsible for selecting the material, type, structure, and parameters of the pump, as well as preparing a quote; this includes determining the appropriate power level for the motor ； Due to the same operating conditions, different pump manufacturers may choose different models, leading to varying results. To reflect any special requirements or preferences on the part of the purchaser, these can be specified along with the other information provided. For example, it might be desired to use multi-stage pumps rather than high-speed pumps for applications requiring high head; the motor capacity should be 1.4 times or more of the shaft power required; pumps must not utilize an impeller design to reduce their net positive suction head; couplings should be from XX company; the pump inlet must have a 6-inch diameter pipe and flanges; the total length of the pump base must not exceed 2 meters; the mechanical seal should be of type 53A; temperature sensors should be installed on the bearings; and the performance tests at the time of shipment should be carried out according to grade 1 accuracy standards as specified in GB3216, and so on. As long as the purchaser has a good understanding of pumps, they can propose any reasonable requirements. Of course, price, requirements, and delivery time are interrelated. All of this content and requirements should be established in the form of a technical agreement or contract.

Bro, you just need to provide the operating conditions of the medium; the manufacturer will then select and calculate the appropriate model based on the parameters you provide； Don’t worry; unless it’s the owner’s requirement that the total current not exceed a certain level, a larger capacity is generally not chosen ； If you impose mandatory requirements on motor power, it will make it difficult for manufacturers to select the appropriate models. For example, the property owner specified that the motor should be 37 KW, but in reality, given the operating conditions, the shaft power requires 40 KW; therefore, a 55 KW motor is the only option ； If we calculate based on the owner’s requirement of 35KW, then the efficiency of the pump would be over 90%. That’s not unreasonable at all – it’s completely illogical: Q

What does it mean when something doesn’t feel right? Is it based on intuition? It was indeed through careful calculation that the error was discovered: o

Find a professional to do the calculation. We usually ask a second supplier to do the calculation.

The efficiency of products from many pump manufacturers falls far short of the required standards; the motor power specified according to the standards is insufficient, so they have to deceive customers by recommending a motor with a higher capacity. Therefore, it’s best to let the manufacturer choose the appropriate motor.

It is usually calculated by the pump manufacturer; if the difference is too large, one should conduct their own verification and discuss it with the pump manufacturer

First, what is the model of your pump, and which brand is it? What are the parameters? Only in this way can we know if it matches. You don’t need to calculate it yourself

You can’t rely entirely on the manufacturer’s product recommendations; otherwise, you’ll be led astray by them. I’ve also talked to technical staff from some domestic manufacturers, and they were confused as well; some of them chose smaller motors in order to win bids at lower prices. Of course, as a user, you also need to convey to the manufacturer the actual operating conditions of the design – there are several such conditions, and it’s important to indicate whether there is a possibility of an increase in flow rate during operation, etc. The most important thing is to master the basic skills. Selecting a centrifugal pump isn’t difficult; you can find out whether the manufacturer’s calculations are correct by doing the calculations yourself. The calculation formulas are available in books and on the internet.