Colglo Blog

Submersible Pumps and Pressure Boosting Units by our Experienced Pump Engineer

Posted by Collister & Glover on Jun 16, 2020 3:05:12 PM
Collister & Glover

We have asked Mike, our Pump Engineer at Colglo, who has  a wealth of experience and expertise, some technical and no-so technical questions about the world of pumps!

Mike had a long and fulfilling career as a Marine Engineer, responsible for the main engines and refrigeration in the shipping industry, following this he spent 5 years designing and costing Halon gas extinguishing systems, moving on to specialising in the repair of large marine engines and generators, mainly working in Liverpool.

Before he came to Colglo, 15 years ago to run the workshop specialising in the repair of all manner of pumps and mechanical seals, he gained some expertise in the specifying and refurbishment of mechanical seals, repairing pumps and gearboxes.

DAB pump

Tell us about submersible pumps and pressure boosting units…

The submersible pumps can be broken down into small sump type pumps, and heavier duty units suitable for more rugged duties such as effluent pumping. They are all centrifugal pumps,  the range can move any amount of water, but not to any great height. The majority of the smaller ranges will pump to about 15mtr maximum. The higher they pump, the lower the flow attainable. As such the required duty should be known prior to pump selection. The same is true with Effluent pumps. These tend to be  Vortex type unit, where the flow does not pass through the impeller. This allows a degree of solids to be pumped. Alternatively if the discharge pipework will not allow the passage of solids without the risk of blockage, these pumps are also available as a grinder units, with blades/cutting edges to macerate the product prior to pumping.

Our pressure boosting sets range from a basic small self-priming pump mounted upon a 20ltr pressure vessel, to bespoke units capable of supplying buildings of any size with a reliable system capable of meeting fluctuating demand at a constant pressure. We also have the Dab E.sybox range capable of supplying small to large domestic properties, or small office type units, with a quiet, small, cost efficient pressure boosting system. Also available with a 450ltr storage tank. This allows the boosting of pressure if the mains are found to be insufficient.


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How do they work?

Centrifugal pumps generate pressure by accelerating the pumped fluid via an impeller. To achieve higher pressures multiple impellers are used, each impeller boosting the pressure into the following – the more impellers, the higher the achievable pressure .The sump pumps mentioned above have a single impeller. The fluid is drawn into the centre of the rotating impeller, and flung to the outer edge, increasing the pressure, and this is then fed to the discharge.  The vortex type pumps have an impeller that generates a spinning cylinder of water, with the pump discharge on the outside of the cylinder. 

Pumping practice and how to fault find?

Inline type centrifugal type pumps require consideration given to pipework configuration, run lengths etc. Incorrectly sized pumps or incorrect pipe sizes can be very detrimental to the pump,

as these conditions can lead to water hammer or cavitation which can both lead to terminal damage. The pump should also have an adequate supply of water, ideally with a laminar flow to help prevent cavitation.

All pump have flow curves, which match the pressure to the flow – the higher the pressure the less it will pump. Ideally the selected pump will have the required duty on the midpoint of the curve. This again keeps the pump within its design parameters and will help avoid issues such as hammer and cavitation.

How to read pump specification (How to do the mathematics for pressure and the like. Essentially how do I spec a pump for a job?)

In order to correctly specify a pump,  as much information as possible will all be useful, the bare minimum is the required flow rate and pressure. The pipework on the discharge side will also have a profound effect on the performance. Every 10mtr rise in discharge pipework will reduce the pressure from the pump by 1 bar, and the longer the horizontal run, the greater the frictional losses in the pipework. For this reason, generally speaking the larger the discharge pipework can be kept, the lower the losses. This can result in a similar performance from a smaller pump, as it will not be trying as hard to push a fluid down a narrow pipe.


Now the fun bit.. 

Describe your job at Collister & Glover in 3 words?                                   

Honest technical evaluation. 

What  are the highlights of your career?                                                      

Being promoted (marine engineer) to hold my own watch, and my wife of 5 months being flown to Montreal to join me.

Can you tell us something we don’t know about you?                             

I cook a mean Sunday roast, or a Thai curry.. 

If you had a superpower what would you choose and why?                     

ESP to see if I could make any sense of politicians thought processes, or what planet they are from.

Which 3 items would you take on a desert island?                                      

Rugby ball, son, beer, wife, Maths book…..


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Topics: DAB, Booster Pumps, E.sybox, submersible pumps, pressure vessel, Lowara, dab pumps, pressure boosting units, centrifugal pumps, pump specification, aquajet, borehole pump, pump engineer, vortex type pumps, rotating impeller, feka, storage tank, pressurisation system