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Commercial Water Pumps - Know What You're Paying For

Discussing pump options in the PASLR showroom

When investing in commercial pumps, customers often ask us why some pumps cost more than others, when they appear to do the same job. If you’re getting a ‘competitive quote’ you need to know what you are comparing and understand how to decipher the pump’s specifications and capabilities – that way you know you’re getting the right pump for the job.

Understanding different types of pumps and models

ISO – stands for International Standards Organisation which is a measurement and performance standard. These are the top of the range pumps, offering uncompromised performance and reliability. In the Davey range these are the ISO CF and CM models.

DIN – stands for Deutsches Institut für Normung (or the German Institute for Standardization). These have less stringent material build standards and compliance testing and lower specification bearings than the ISO range, making them significantly cheaper than the ISO pumps. Components are not necessarily interchangeable between manufacturers. In the Davey rage these are DIN CS models.

Propriety Models – most manufacturers have their own range. Davey have the CD and Dynaflow ranges. Davey’s pumps are independently tested with accurate curves.

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Davey ISOspec pumpDavey ISOspec pump

  • Designed & Manufactured to ISO2858 standard, includes:
  • Table E flanges
  • Performance compliance – within the standard
  • Dimensional compliance – interchangeability with other makes
  • 1600kPa rated – casing operating pressure
  • Max casing pressure 2400kPa – test pressure

“We don’t compromise on quality. The performance and build quality you get with an ISO pump may cost a little extra upfront but will require less maintenance and costs on an ongoing basis.”

It’s all in the curve

When we specify a pump it’s crucial that we find the Best Efficiency Point (BEP) or ‘sweet spot’. We do this by comparing performance on a curve. What we are looking for is the flow rate in comparison to the amount of energy the pump is using to achieve that flow rate.

How to read a curve
Fixed speed curves - 1450 rpm
Centrifugal pumps run best at or near BEP

When a pump is running at its most efficient you not only get the flow and pressure of water you require but are also protecting your pump. If your pump is performing too far right of the BEP you run the risk of cavitation (the rapid creation and subsequent collapse of air bubbles in the water). If you are too far to the left you could find your pump overheating.


It’s important to note that different manufacturers pumps can be compliant to the performance standards BUT not identical in performance. This means the same size pumps that are dimensionally identical (footprint and all centre lines) will have slightly different performance curves for different manufacturers.

To ensure we specify the right pump for the job we need to know;

  1. Details of the motor including speed and current rating of the motor (i.e. the info on the data plate)
  2. Power supply
  3. Connection size of the pump
  4. Size of the pipe work connection and whether they are flanged
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