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PRODUCTS PNEUMATICS & HYDRAULICS


A COMPACT QUICK-CHANGE PERISTALTIC PUMP


New from Pump Engineering is the Ponndorf P Delta peristaltic pump. According to the company, the unit features a simple, one handle operation which disconnects/reconnects the pump head to enable quick hose replacement without the need for tools, as well as fast and effective cleaning. Compact in size so suitable for


applications where space is limited, the pump also offers non-contact, low-pulsation operation and it can run dry safely and self-prime from up to 8m. Standard three roller models or four roller models for smoother flow are available for handling flows up to 975 l/hour with a maximum pressure of four bar. Hose materials are available to


suit a range of applications including natural rubber and white food grade Ponnprene as approved by the FDA. The pump is suitable for applications


involving delicate or shear sensitive fluids, such as in the food, brewing, paint, pigments and printing industries where quick-changes of ingredients, additives or inks may be required.


Pump Engineering T: 01903 730900 www.pumpeng.co.uk Enter 212


DESIGNING HIGH PRESSURE PUMPS FOR HARSH ENVIRONMENTS


Selecting the right pump for your application will depend on a number of factors. For a start, you will need all the necessary information relating to the application and the fluids involved. The manufacturer will then be able to propose a suitable design that will integrate with the existing equipment and control systems, and provide a reliable and efficient pumping system. Pump designs tend to fall into two categories –


reciprocating and centrifugal – with the latter the most common. With this, using an impeller, located in a volute, the fluid is pressurised by transferring the mechanical energy of the motor to the impeller and increasing the velocity of the fluid, increasing pressure. Typical applications are where a lower system pressure is required. A reciprocating pump discharges liquid by


changing the internal volume of the pump and uses non-return valves (NRVs) at both the inlet and outlet ports. These can produce 1000 bar in pressure, however ultra high pressure pumps capable of over 7000 bar are available. The pump produces a fixed volume of fluid displacement at a given speed and provides a constant flow, regardless of pressure. This means that variable capacity can be achieved by changing the pump speed. In contrast, the centrifugal pump would be forced up and down the performance curve, varying the flow which may cause problems for


22 SEPTEMBER 2014 | DESIGN SOLUTIONS


the application. Reciprocating pumps are more often controlled by a variable speed controller. One crucial aspect of pump design is the


associated piping and connections, which can cause serious problems if the system has been poorly designed. Cavitation is one of the more common issues that arise when pressurising fluids and this can cause severe pressure spikes that cause damage to internal pump components. Additional issues include vibration and noise. The pump design must also incorporate safety


features, including a safety valve which should allow the entire pump capacity to flow, while the opening point should be set at 10% above the operating pressure. In addition, the pipework associated with the safety relief valve should be properly sized to ensure adequate flow conditions. RMI includes a number of safety circuits to


prevent a potential dead head condition, including a pump safety relief valve, which protects the pump against a potential hydraulic lock. In addition, there are oil temperature and pressure sensing circuits as well as motor overload monitoring, all of which can indicate a potential issue with the system and allow the pump to be stopped prior to any potential damage being caused. A pump’s sealing system is equally important when considering its safety as well as overall performance and reliability. For high


pressure reciprocating pumps the task is typically performed by the stuffing box, which contains packing and lubricant in configurations depending on the application. This packing is a service item and should be able to be replaced without too much interference with the main pump assembly. Efficiency is next. With reciprocating pumps, the


design offers greater mechanical efficiency, which means that a smaller prime mover can be used and less energy is consumed. By carefully selecting the correct motor and matching it to the pumping system, an efficient combination can be created. Further efficiency benefits offered by RMI’s


design can include the stored energy offloading system which reduces energy consumption by allowing the pump to idle in a pressurised standby condition, while still being able to quickly and efficiently return to full service when required. RMI has also introduced the ODIN (On Demand


Intelligence) control system. This uses a range of data supplied from equipment used in the process of continuous longwall mining and uses it to calculate the changes in demand for hydraulic fluid before they occur. In this way ODIN can modulate the pump speed and change the flow and pressure characteristics to meet demand.


RMI Pressure Systems www.rmipsl.com


Enter 214 / DESIGNSOLUTIONS HYDRAULIC ACTUATOR HELPS FLOOD CONTROL


The Environment Agency (EA) has installed an hydraulic, multi-turn actuator as part of a new penstock control system, which will make the flood defences at Market Weighton in East Yorkshire compliant with the 1975 Reservoirs Act. For this, the EA appointed Jackson as the main civil engineering contractor to design and construct


a weir, spillway and a stilling basin at the site together with a new inlet structure on the culvert. A new cast iron penstock will replace the old one and will be controlled by a hydraulically powered, multi-turn actuator from Centork, which was acquired by Rotork in 2011. ECS Engineering Services was responsible for the installation of the penstock and the new control kiosk, which is located on higher ground to avoid the flood water. For the application, the hydraulic actuator is powered by pressurised oil and provides a 4-20mA


position signal back to the control panel, which is in the kiosk with the hydraulic power pack. The actuator will be used to control the new cast iron penstock, which was supplied by Waterfront Fluid Controls. The design has been made as simple as possible for reliability. During heavy rainfall, the improved containment system will collect the flood water and then release it


back into Mill Beck, which flows into Market Weighton, under the control of the penstock. This can be controlled from a central control point via the telemetry station in the control kiosk, allowing an engineer to adjust the position of the penstock remotely. This allows a much quicker and safer response which can start to allow the flood water to dissipate at the earliest opportunity.


ECS Engineering Services www.ecsengineeringservices.com Enter 213


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