Pump Selection

When it comes to selecting a pump the more detailed information you can supply, the better the result. Several variables come into play impacting how long a pump will last and how it will operate. If you aren't sure about how to select the right pump, or what information you should know you are best to just give us a call on 1300 727 422.

To get a better idea of the variables, take a look below at our critical list of 7 things you should know before selecting the pump that will be the right one for your application.  

Alternatively, you can use the following handy table as a general reference to help you select the pump right for you.

NOTE - This table assumes that the water tank is above ground and that the pump is beside the base of the tank with less than 10m of pipe to the house.   All the Grundfos CMB-SP or CMBE series pumps listed have automatic on/off controllers that will protect against running dry. Excellent quality and when you combine your pump with a pressure tank into your system you will reduce the number of pump starts by up to 50%, ins ome cases even more, this saves money and extends the life of the system. 


Household Details Option 1 Option 2. More Pressure Pressure Tank Warranty
Small House, 1 bath, 2 people, 1 level CMB-SP-1-36 CMB-SP-3-37 60 Litre 4 years
Small House, 1 bath, 1-3 people, 2 levels CMB-SP-1-36 CMB-SP-3-37 60 Litre 4 years
Medium House, 2 bath, 1-4 people, 1 level CMB-SP-3-37 CMB-SP-3-47 80 Litre 4 years
Medium House, 2 bath, 1-5 people, 2 levels CMB-SP-3-47 CMB-SP-3-56 100 Litre 4 years
Large House, 2.5 bath, 3-6 people, 1 level CMB-SP-3-47 CMB-SP-3-56 100 Litre 4 years
Large House, 2-3 bath, 2-6 people, 2-3 levels CMB-SP-3-56 CMB-SP-5-47 100 Litre 4 years
Very Large House, 3-4 bath, 2-8 people, 2-3 levels CMBE-3-62 CMBE-5-62 100 Litre 4 years

1. Process Liquid Properties     

What type of liquid is the pump intended for? Below are process liquid properties that must be considered before selecting a pump.  

  • Liquid viscosity (see below for descrption)
  • Temperature
  • Specific gravity
  • Vapor pressure
  • Solids present & concentration
  • Shear sensitive
  • Abrasive or Non-abrasive

2. Materials of Construction--

What materials of construction are compatible with the process liquid or any other liquids the pump might come into contact with? Chemical compatibility charts are available to help you identify the most appropriate materials of construction for the pump. 

3. Is the Pump Critical to Plant Operation?

In critical applications, where downtime is NOT an option, more expensive, heavy-duty pumps with special features can be chosen. If pumps can be removed from service for maintenance, less expensive options could be considered. 

4. Pump Inlet Conditions

You don’t want to starve a pump. System Net Positive Suction Head (NPSH) available is calculated by knowing pump inlet pressure and liquid vapor pressure. Always make sure NPSHA exceeds pump Net Positive Suction Head (NPSH) required.  

5. Pump Environment

If your pump will be outside, special construction or installation considerations may need to be made for freezing temperatures. If the environment is hazardous, contains explosive vapors or dust, special motor features will be required. These are just a few examples of environmental conditions to consider.

6. Power Source Availability

What is the available power onsite - this will help you decide between a solar pump or an AC pump selection 

7. Flow Rate and Pressure

What is your total volume and how much time you have to move the fluid will determine flow rate. Pump differential pressure can be calculated by knowing pipe size (length & fittings), static lifts, and system equipment (filters, valves, etc.) friction losses.

By understanding the above factors, you're arming yourself with the knowledge necessary to select the right pump. No matter the application, you can feel confident with your next pump selection!

Contact us today for assistance with pump selection, or submit your online quote request. Our staff of degreed Engineers are happy to provide technical assistance.

What is Viscosity?

When selecting a pump for your system, it's important to understand the fluid you're pumping to its fullest extent. What happens when it's heated? What happens when energy is added? When choosing the pump you need, there are a number of factors that come into play, and viscosity of the fluid is one of them.  

Viscosity is a fluid property which is resistance to shear when energy is applied. This characteristic must be taken into account when making process pump selections and in determining friction losses in a fluid process system. Centrifugal pump performance is based on testing with water. Positive displacement pumps performance is based on using water or oils where lubrication is required.

Viscosity is commonly expressed in units of SSU (Seconds Saybolt Universal), cPs (Centipoise) or cSt (Centistokes). 

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