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PUMPING SYSTEM EFFICIENCY A guide to optimising energy consumption


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Steve Schofield, Director and CEO of the British Pump Manufacturers’ Association (BPMA) offers some basic information and guidance on purchasing, maintaining and designing pump systems.


uSee author biography below.


umping systems account for nearly 20% of global electrical energy demand and between 25 -50% of the electrical energy usage in certain applications. Pumps are the single largest user of electricity within industry across the European Union,


consuming over 300 TWhpa of electricity, which in turn accounts for over 65 Mton CO2.


It is also well documented that rotodynamic pumps which account for 80% of the installed base are between 20-30% oversized. There is, therefore, huge potential to save energy if rotodynamic pumps are properly sized and operated.


To identify if a pumping system is sized correctly make the following checks: uAre you wasting liquid flow? uAre you creating additional pressure? uWhat is the control philosophy? uIs there excessive noise in the system? uProactive equipment replacement to current EU legislation


Understanding drive technology:


Use latest EU regulation to achieve best possible drive efficiency – uVariable speed drive uIntegrated control and monitoring uPermanent magnet technology


This article does not suggest or promote any single supplier or technology. It does however recommend that you choose a supplier that is a member of the BPMA. See www.bpma.org.uk


The great majority of pump systems are not designed with energy conservation as a major consideration. If pump systems are initially designed on an energy efficient basis and pumps are correctly applied and sized the energy savings will often be in excess of 50%.


To design an energy efficient pump system all of the following criteria should be taken into account: uBasic plant layout uPipework configuration and restrictions uLiquid velocity in pipe work uSystem characteristics and pump selection uPump/System control


Low energy costs are a direct result of selecting the correct pump and matching it to the system.


When selecting a pump it is important to determine the required flow and pressure to be generated by the pump. The flow may be determined by a process requirement, by the heating or cooling required in the system or by the peak water demand for utilities. The pressure required might be to elevate the liquid within the system or to overcome the pressure losses in the system created as liquid passes through it.


It is important to know as much about the pump system as possible and to create a pressure/flow profile for the system. The energy required to drive the pump is directly related to the flow and pressure required. To generate high pressures generally leads to designs, which may be inefficient, and


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stablished in 1941, the BPMA is the UK Trade Association representing the interests of the UK manufacturers of liquid pumps.


Steve is currently


responsible for all of BPMA’s activities. He manages a small team who offer information to members on Technical, Training, Standards, legislative, marketing and energy related activities.


Since joining the BPMA he has also been actively


involved in many of the European Commission energy programmes such as Pump SAVE, Motor Challenge, ProMot and DEXA.


In 2000-2002 he was involved in the working group, which produced the international guide on Pump Life Cycle Costing. In 2003 he worked with Future Energy Solutions to produce the Best Practice Guide on Variable Speed Pumps and then subsequently took on the task of secretary for producing the international


guide for Variable Speed Pumping. In 2005 he again took on the task of secretary to produce the international guide for System Efficiency in Rotodynamic Pumping Systems.


In the UK for many years he has worked closely with government departments such as Defra and Decc . In Europe he is currently the Secretary for Europump on Lot 29 a new study on various types of pumps, however his main


responsibility in Europump is 34 BUILDING SERVICES & ENVIRONMENTAL ENGINEER APRIL 2016


therefore it is important that neither the flow nor the pressure is over specified.


Variable speed drives can save energy


Using Variable Speed Drive and High Efficiency motors has made significant energy savings. Variable Speed Drives are used to continually adjust the speed of the pump to the demand.


When building a new pumping system, most pumps are selected with a "safety factor" for potential future uprates or to allow for wear in the pump or fouling of the system. Often there are many different parties involved in specifying and building a system and the safety factor can grow exponentially. This results in the pump delivering much higher flows than required. There may also be the need to vary the flow due to process conditions or varying heating and cooling needs within buildings.


Traditionally, throttling is used to regulate flow in a pumping system. While throttling reduces the flow, the motor is still running at full speed and works even harder as it has to work against a restriction. By reducing the speed of the motor, the variable speed drive ensures no more energy than necessary is used to achieve the required flow. A centrifugal pump running at half speed consumes only one-eighth of the energy compared to one running at full speed. Utilising an Electrical Variable Speed Drive is the simplest and most economical way of controlling the pump and matching it to the pump system.


VSD considerations


When fitting VSD to a pumping system, output and input filters should be considered, along with insulated motor bearings.


Maintenance When maintaining pumping systems it is recommended to use


working with the European Commission to ensure a Systems Approach on Pumping Systems will eventually become a reality across Europe. He is currently the convenor for ISO TC 115 WG 7 working on ISO 14414 pump system assessment standard and is also a member of the working groups writing the ISO 50001 and EN 16247 series of energy management and audit standards.


He also has close links with the Department Of Energy


in the USA on Pumps Systems and training and recently carried out a review of pump system training for UNIDO (United Nations Industrial Development Organisation).


He has given papers on energy related issues in the UK, Europe, USA, South Africa and Singapore. Prior to joining the BPMA in 1998 he worked in the pump industry for 25 years having held appointments with Mather & Platt/Weir Pumps, Durco/Flowserve and latterly Hayward Tyler.


VISIT OUR WEBSITE: www.bsee.co.uk


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Low energy costs


are a direct result of selecting the correct pump and matching it to the system. When choosing a pump it is important to determine the required flow and pressure to be generated by the pump.


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