Precision pumping

Selecting the most suitable pump for a specific application or process system is not particularly straightforward because the variety of pump technologies from which to choose is getting ever wider.

Rotary positive displacement pumps, peristaltic (or tube) pumps, high pressure triplex plunger pumps and reciprocating positive displacement pumps all cross application boundaries when there is a requirement to introduce a specific volume of liquid into a process system.

Where an application involves the in-line proportioning and dosing of liquids, historically it has been the reciprocating positive displacement process pump that has dominated the market. The dosing pump concept originated in the 19th Century, when industry started to develop in Europe and concerns about healthcare and water quality were growing.

The oil and gas and chemical industries are a particularly strong area for our diaphragm metering pumps

Lewa’s Florian Kieninger

Since then technology changes have advanced by the growing need for increased safety, environment protection and most recently energy efficiency. The metering pump is highly versatile and is ideally suited to continuous, in-phase metering of single or multiple liquid systems at varying rates. Significantly, it is the only pump with two flow adjustment methods, speed and stroke length, that can be used independently or simultaneously to provide optimum performance.

For instance, in a process where an ingredient has to be added accurately to a varying main flow, the proportion can be maintained by speed adjustment, while any corrections necessary to maintain product quality can be made by adjustment of stroke length. This means that the metering pump can be finely tuned to the requirements of the process system.

Pump categories

Metering and dosing pump technologies fall into three categories: piston/plunger, mechanical diaphragm and hydraulic diaphragm.

The standard plunger pumphead, consisting of a housing, displacement plunger, seal arrangement, pump valves and suction/discharge side connections, is commonly used where high pressures and high flow rates are encountered. The simple design and small number of components allows a low dead volume and high volumetric efficiency.

Mechanically coupled and hydraulically actuated diaphragm pumpheads can be classified as relatively recent developments and these types of pumpheads are usually specified where toxic materials are being handled and leak-proof performance is required.

As a result of the wider variety of materials that can be used for diaphragms, pumpheads are now capable of accommodating hazardous, toxic and dangerous liquids at variable flow rates and pressures. With greater emphasis being placed on safety and environmental considerations, and as further legislation is introduced, users are moving towards diaphragm pumps and away from the traditional plunger design.

Hydraulically actuated double diaphragm pumpheads now incorporate diaphragms made from either PTFE or stainless steel, and are capable of handling pressures of up to a 1000bar and above.

Market dynamics

The international companies that have a dominant presence in the metering pump sector include Milton Roy, IDEX with its OBL and Pulsafeeder brands, Prominent, SPX Bran+Luebbe and Lewa. All report a growing demand for their products, with the oil and gas and water treatment sectors leading the list of industries.

Milton Roy global product line manager Axel Bokiba says he sees the market being driven by unconventional oil and gas production such as deepwater and shale, and pump controllability for better operational expenditure management such as smart pumps, condition monitoring and web-based remote control.

“The market has changed significantly, with the deals getting more global as well all the players striving to leverage the rise of recently developed countries,” says Bodika.

IDEX OBLsrl general manager Daniele Di Cesare agrees that one of the biggest sectors right now is oil and gas, with new techniques of oil extraction such as fracking and floating production, storage and offloading (FPSO) systems behind the increase in demand.

Likewise, Lewa corporate development manager Florian Kieninger highlights the market for upstream and downstream oil and gas as a growth area due to the high capital expediture of big end customers and the high cost of oil globally.

“The oil and gas and chemical industries are a particularly strong area for our diaphragm metering pumps,” says Kieninger.

SPX, which has a specific brand focus on the oil and gas market, including offshore platforms, sees a similar pattern, commenting that the market drivers influencing product developments include accuracy, controllability, size, weight and pressure capability.

“At SPX, our Bran+Luebbe brand has specific focus on the oil and gas market, including offshore installations, “ says SPX commercial lead Steve Digby.

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