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Monthly Archives: January 2018

  • Positive Displacement Pumps vs Centrifugal Pumps

    Whilst positive displacement pumps and centrifugal pumps are two disparate branches of pumps that are also two of the most commonly used, the differences between them are slight, making it tricky at times to decipher exactly which one should be used in which scenario. To establish the differences and similarities between the two, as well to clarify which pump is more cost-effective and which is best at handling high-viscosity fluids, we have put together this guide.

    What are the fundamental differences?

    Centrifugal pump Centrifugal pump

    Centrifugal pumps are rotodynamic, which means they work by constantly imparting energy to the liquid through the movement of a propeller, rotor or impeller. Centrifugal pumps are used more frequently than positive displacement pumps, and they owe this status to the simplicity of their design, which also makes them cheaper. With few moving parts, maintenance and repair costs are limited. They are also relatively compact, making them ideal in situations in which space is at a premium.

    Positive displacement pumps meanwhile are not rotodynamic, and rely on trapping on a fixed volume of liquid and forcing it through the pump’s discharge. They can be distinguished further from centrifugal pumps by the means by which they impart energy to the liquid. Rotary pumps work through rotation of the pump element, while reciprocating pumps work through a constant back-and- forth motion.

    How else do they differ?

    The simple structure of centrifugal pumps allows it to be easily replicated in a variety of different materials that cater to a number of different purposes. For example, plastic and cast iron replicas are used for less intensive applications whilst bronze and stainless steel editions are better equipped to cope with more corrosive fluids. The popularity of centrifugal pumps can also then be attributed to this unique kind of versatility.

    Positive displacement pumps operate at a slightly lower speed, they are superior in a number of ways.What separates positive displacement pumps from centrifugal pumps (and justifies the gulf in cost) is their ability to maintain their efficiency in spite of varying viscosity, pressure and flow. Their flow rate remains high thanks to their internal clearances.

    What are they used for?

    Centrifugal pumps are best suited to pumping low viscosity liquids at low pressure at a high flow rate.  When faced with a fluid with high viscosity, the flow rate of centrifugal pumps drops dramatically due to frictional losses within the pump and damage and cavitation can even occur. Similarly, if any variations in pressure arise, the performance of the pump will fall. For these reasons, centrifugal pumps are normally used in the transfer of water, or even thin fuels and chemicals.

    Positive displacement pumps' ability to keep a constant flow rate makes them far better suited to pumping fluids with higher viscosities than centrifugal pumps; making them ideal for pumping slurries, oils and sewage. The petrochemical and wastewater industries are popular destinations for positive displacement pumps. One widely respected and esteemed manufacturer of a form of positive displacement pump, progressive cavity pumps, is mono pumps.

    mono pumps Positive displacement pumps

  • The Wastewater Treatment Process

    Over time, the pressure imposed on water supplies in the UK by climate change has facilitated the construction of close to 9000 wastewater treatment plants. Slowly but surely, they are becoming an important and even ingrained part of how we as a society push back against global warming. Yet so few of us understand or are even aware of the process that transforms the wastewater that leaves our toilets, sinks and showers into potable drinking water. To provide you with a bare-bones look at the basics of the process, we have put together this summary of the role of the wastewater treatment plant.

    wilo pumps

    Screening process

    After wastewater is carried away from homes and, via a network of pipes and submersible wilo pumps, arrives at a wastewater treatment plant, it undergoes a screening process. To separate all of the biggest debris that so often accumulates, from the wastewater itself, the wastewater travels through a screen that essentially acts a sieve.  The type of screen used varies from plant to plant but the most commonly used screens include both coarse and fine screens, as well as the newer step screens.

    Primary treatment stage

    At the primary treatment stage, the mixture, newly relieved of its biggest and most easily extracted debris, is placed in a sedimentation tank. Within the settlement tanks, the heaviest material sinks to the bottom to form a layer of sludge. Large arms or scrapers then push this sludge towards the centre of the tank, where it can be disposed of or treated further, leaving a more refined fluid behind. The purpose of the primary treatment stage is to remove solids from wastewater in order to

    Secondary treatment stage

    The secondary treatment stage involves treating the wastewater to rid it of any remaining organic matter. This happens two ways - through the aeration of the wastewater and through the addition of bacteria. By pumping air into a large tank containing wastewater, bacteria are allowed to grow and thrive, where they break down any remaining nasty substances into harmless organic matter.

    Final treatment stage

    After undergoing this chemical treatment, wastewater is placed into a humus tank which separates the wastewater into its final constituents. Any remaining bacteria sinks to the bottom, forming sludge, which is then sent for secondary treatment, leaving clean water behind. Depending on which body of water the cleansed wastewater is sent to, an additional step is sometimes carried out - the remaining water can be filtered through a bed of sand to remove any resolute particles.

    Once the entire water reclamation process has been completed, the treated water can be sent to any number of different locations. The majority of treated wastewater in the UK goes back into the country’s streams and rivers and some is even discharged into the sea. Because treated water is subject to such rigorous testing by regulatory bodies, all reclaimed water bolsters the quality of water throughout the UK, not to mention availability.

  • The UK Locations Most At Risk of Flooding

    As global warming continues its march relatively unimpeded, sea levels and the incidence of tumultuous weather will continue to rise. And while many may assume that coastal regions of the UK are far and away the most susceptible to flooding, data collected by the Environment Agency actually shows that the network of rivers and tributaries that wind their way throughout Britain make inland areas just as vulnerable.

    Boston and Skegness

    It is however, a coastal region that is most in dangerous in terms of flooding. Boston and Skegness, both perched precariously on the Lincolnshire coast, are subject to frequent storm surges that plague that particular stretch of the east coast. When deep depressions track across the Atlantic Ocean (resulting in lower pressure and rising sea levels) winds push the surface waters forward as part of a process known as wind drift. When these depressions reach the North Sea, they are forced southwards. Because this water cannot escape through the Dover Strait, it accumulates in this region and causes sea levels to rise dangerously, afflicting the east coast in the process. Just earlier this month, over 3000 residents were forced to evacuate their homes in the face of warnings of gale force winds and high tides.


    Nottingham is perhaps the most populous area that is perpetually under threat of sustaining damages from flooding. The city has been associated with flooding throughout its history, so much so that indentations marking the height of its historic floods have been engraved into Trent Bridge since 1852, and had been marked into the Hethbeth Bridge before it. The concern over flooding is so dire that £1 million of funds have been invested into flood defences to protect the Mapperley Park region of Nottingham. Everything from flood-resistant doors to storm gullies is under consideration.

    Vale of Clwyd

    The low-lying nature of the Vale of Clwyd puts it in jeopardy of regular flooding. The Welsh region owes this unenviable status not only to how low-lying it is, but also to its proximity to both the River Clwyd and the Irish Sea. Any time flash floods are forecast, more than 137,000 properties are at risk of being enveloped by water. The floods that devastated the region in 2012 are just one example of the area being affected by flooding.


    lowara pumps uk

    The River Thames continually threatens to put the residents of Windsor at risk. The 5000 residents that call the river’s banks their home have experienced severe flooding numerous times over the course of the last decade - the worst of which was the floods of 2012. The majority of residents were affected and train lines were wrought with delays and cancellations.

    If you live in an area that poses a risk of flooding, it is well worth opting to buy from lowara pumps UK. With a wide range of drainage and sump pumps available, a Lowara pump is a dependable ally for anyone who is wary of flooding affecting their home.

  • The Importance of Centrifugal Pumps in Industry

    As the name suggests, a centrifugal pump uses centrifugal force to pump a liquid containing solids. Centrifugal force is generated by the rotation of the impeller, which causes the liquid to leave the impeller’s vanes at a higher velocity than it had when it entered. In turn, this outward flow creates a pressure differential. Pressure is lowest at the impeller eye, which allows more liquid to enter - resulting in a constant flow of liquid through the pump.

    What differentiates a self-priming centrifugal pump from a standard centrifugal pump is the ability to pump liquid without the pump casing being entirely filled with liquid - thanks to the inclusion of a partial vacuum that allows self-priming pumps to rid themselves of air. Both standard and self-priming centrifugal pumps are an integral part of the water desalination, mining and petrochemical industries amongst others.

    Water desalination plants

    Water desalination

    With the UN predicting that 14% of the global population will be suffering from water scarcity by 2025, water desalination plants are set to become more vital than ever. By separating dissolved salts and other minerals from otherwise unusable water, water desalination plants are able to recover potable water for the areas that need it most. And, although desalination methods vary dramatically (from nanofiltration to electrodialysis), what unites these processes is the inclusion of centrifugal pumps. More than capable of transporting solid-containing seawater efficiently, self-priming centrifugal pumps are especially popular with high capacity water desalination plants.

    Mining industry

    The mining industry is unconventional in that it uses centrifugal pumps in an altogether different manner to similar industries. In the context of mining, despite being the same mechanism structurally, a centrifugal pump is known as a froth pump, because of the product it is altered to produce. Mineral processing owes the separation of precious minerals from gangue and bitumen to the intervention of centrifugal pumps. As well as actually playing a part in processing the minerals themselves, centrifugal pumps are also used to transport the slurries and solid-containing fluids that accumulate during the mining process.

    Petrochemical plants

    The petrochemical industry is worth well over $500 billion, and it is also an industry with a heavy reliance on centrifugal pumps. Given not only the value of the petrochemical components at play, but also the very real danger of them igniting means that the robustness of the centrifugal pumps involved is of utmost importance. Consequently, the production of plastics, rubbers and dyes is indebted to the use of well-designed centrifugal pumps.

    varisco pumps

    If you are an organisation looking for a robust self-priming centrifugal pump you can rely on, then look no further than Varisco pumps. The Italian brand has been a world leading pump manufacturer for seven decades. What separates Varisco from their competitors, besides their wealth of experience, is their commitment to variety - without sacrificing quality. Both stainless steel and bronze centrifugal pumps are available for industrial use, as well as a range of different power options for each edition - ensuring that you will find a centrifugal pump that is ideal for your use.

  • Money-Saving Tips for Winter

    Winter is a time where we all get to relax more than we should, eat more than we should and spend more than we should. When it comes to spending money though, we want to be sure that it goes on gifts for our closest friends and family – not on mundane but essential updates to our home. Unfortunately, the festive period also brings with it some of the worst weather the year has to throw at us, making repairs to plumbing and heating apparatus all too common. To ensure none of this seasonal reaches you over the winter months, you may want to consider some of the following changes to keep your bank balance as healthy as possible.

    Shower pumps

    salamander shower pump

    Salamander are one of the leading pumps brands around, and from their base in the South East, they have been providing UK homes with the highest quality pumping products for years. A core part of their range that will guarantee you perfectly pressured showers in spite of any boiler problems that may arise during the colder months, is the salamander shower pump. A shower pump of this quality is as effective as they get, and will keep your water pressure intact without any of the associated extra cost that you might otherwise expect.

    Circulating pumps

    circulating pump

    Whilst you may not be familiar with circulating pumps, they are actually one of the most cost-effective heating products money can buy. By ensuring that hot water is distributed evenly throughout the home, any additional and unnecessary expense is circumvented. Not only does the efficiency of a circulating pump minimise the cost of your water bill, it also ensures that extra energy won't be expended heating up water that won’t be used - allowing you to rest assured that your actions aren’t taking a toll on the environment.

    Grey water recycling

    grey water recycling

    Similarly, a grey water pump is ideal not just for those of us who are desperate to safeguard the health of the planet for the foreseeable future; it is also perfect for those of us who are more conscious than ever of exactly how much money we are spending (which is especially true during the festive period). A grey water recycling pump achieves both of these things by repurposing all of the grey water that would otherwise go to waste (from your baths, showers, dishwashers and sinks) for use elsewhere in the home. Given that a grey water recycling system is more than capable of reducing water usage by up to 50%, the upfront investment is miniscule and one you should be certain of considering.

    Sump pumps

    sump pump

    The threat of flooding is never higher than over the bitterly cold and wet winter months - whether that is from a particularly heavy downpour or pipes frozen to the point of bursting. Fortunately, there is one simple step you can take to stave off costly water damage. Installing a sump pump provides a hardy barrier to flooding by automatically casting away any water that may accumulate in the home. Once again, it is an essential initial investment that will easily repay itself over time.


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