How to Check Flow Rate and Head Pressure


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Industrial pumps are expensive to buy or replace. If you suspect that your pump isn't performing as it should, there are ways to check the flow and head pressure. This will let you know if you need to replace your pump, or simply carry out maintenance.

What is Flow and Head Pressure?

Engineering solutions for flow and head pressure have an interesting history, but we won't bore you with the background. Let's just deal with what you need to know:

  • Flow:  Also referred to as flow rate, this describes the volume of fluid which a pump can produce in a given amount of time. Usually measured in cubic metres per hr (m3/hr), litres per second (L/sec) or litres per minute (L/min), the higher the number the larger the volume of fluid a pump can produce per second.
  • Head Pressure: Simply put, 'head' refers to how high a pump can raise water. There are some in-depth explanations of head out there, but let's try and keep it simple. The higher the head of water you need to pump, the more pressure you have. The higher the pressure (commonly measured in PSI or cPa), the higher the head. The more pressure a system has, the higher it can transport the water.


Evaluating Flow and Head Pressure

First of all, you need to know if your pump is performing to manufacturer specifications. If it is and you're still not satisfied, then it could mean that you need a pump capable of greater head pressure and/or flow. Your first port of call then should be to have a copy of all documentation from the manufacturer. If you have misplaced these, contact us and we'll be happy to provide you with the correct pump curve and other documents you'll need.

Once you have these, you can then compare the recorded flow rate with what the manufacturer states it should be. There are several ways to do this, which include:

  1. Directly measuring flow by using a flowmeter at the discharge side. This will give you a precise measurement, but may not always be an option if there is no flow meter. Also, the type of flow meter you can use will vary depending on the fluids used and the range of diameters to be measured.
  2. If a flow meter isn't an option, then you can try to calculate the flow yourself. Here are a few suggestions of how to calculate flow rate without a flow meter. Just remember that without a flow meter your calculation will not be as precise.

Once you have your flow rate you can compare this to what it should be on the pump curve.

You can measure the head pressure by installing a pressure gauge or manometer and comparing this with the manufacturer's documentation for the diameter of piping in the system. If this is lower than advertised then the pump is not performing correctly and may need to be repaired or replaced.

Talk to our pump experts today to select the right pump for your application.


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