-29-March-2006

Bringing peristaltic advantages to positive displacement pumps

New designs of syringe and diaphragm pumps hope to cut costs for manufacturers and packers of liquids, creams, and semi liquids. CCL Concept and Developments Ltd discusses how it has developed a new pump technology, which brings the advantages of peristaltic pumps and single-use systems to a range of positive displacement (PD) and transfer pumps.

Current trends within the biotech industry are seeing a boom in single-use systems (disposable) manufacturing. These systems are made up of a range of disposable components from valves, liners, filters and tanks to tubing, all designed to enable a fully-integrated production line in which the product never makes contact with any stainless steel equipment, avoiding cleaning procedures and making batch changeovers as straightforward as changing a bin liner. The cost savings achieved are reported to increase as batch changeovers become much speedier, and simpler. Complex cleaning and validation procedures can also be avoided, improving the efficiency of the production process.

Currently these benefits have been limited to the biotech industry, but as whole life costs are becoming increasingly important across other industries, this new pump technology will make it possible for a greater number of companies to benefit, particularly in the pharmaceutical, cosmetic, toiletry, food and industrial filling sectors.

A new syringe and diaphragm pump based on a new technology designed by CCL Concept and Developments Ltd will provide benefits for:

• Manufacturers and packers of liquids, creams, and semi liquids

• Users of dosing and metering pumps

• Users of Peristaltic pumps

Those involved in industries where a high numbers of batch changeovers or product changes occur, will be familiar with the problems of stripping and cleaning product transfer or dosing pumps. They will know only too well how costly and time wasting it is to wait on engineers to exchange dirty pumps, or have to take equipment off line whilst contaminated parts are cleaned. In many applications, pumps are sterilised or autoclaved prior to reassembly and re use, and sometimes swabbed before storing them for later installation

Those who endure ‘Clean In Place’ or ‘Sterilise In Place’ (CIP/SIP) will need to establish a validated CI/SIP procedure for each product, and in many cases the production line down time can be several hours. During these procedures, toxic products create a further headache of safely disposing of huge volumes of contaminated wash water.

Because of the concerns over cleaning and sterilising conventional PD dosing pumps, many difficult dosing applications currently lend themselves to alternatives such as peristaltic pumps, time/pressure or weigh cells or flow meters. Whilst some of these methods perform reasonably well, traditionally, compromises have been made when using these methods of dosing. Here we outline the drawbacks of those alternatives:

• Weigh cells – using weigh cells to measure a volume is not an ideal solution and this method should be reserved for sales by weight only. Additionally, it is a usual requirement of this process to duplicate the weighing procedure (firstly when the container is empty and secondly when full) to give a tare weight. This involves a double set of weight accuracy figures that doubles the tolerance achievable and this method is generally limited to larger volumes or slow speeds.

• Time pressure also produce good results, however in many circumstances, it involves calibration for each new batch or new product. This is because the viscosity and fluidity of the product may vary (even more so when natural products are in the recipe). This presents a particular difficulty for Contract manufacturing Organisations (CMO’s).

• Flow meters as with time pressure, depend on standard solutions with identical properties, so if the required dose accuracy is to be achieved, each batch or new product has to be calibrated prior to production.

• Peristaltic pumps have been much improved in recent years thanks to microprocessors and other mechanical improvement. One disadvantage of peristaltic pumps is that their accuracy can be adversely affected by fatigue that occurs in the walls of the plastic tubing. This means that not only do they have to be calibrated for each new tube set used, but they also need to be calibrated during production to maintain dosing accuracy. As a result, it is common practice to keep tube diameters as small as possible, which ultimately leads to slower dosing cycles or more pump heads than usual.

The new technology can be used either for product transfer or for metering as it is suitably for the transfer or dosing of liquids, creams, and semi liquids. Both a syringe pump and a diaphragm pump incorporate the this approach. These pumps operate by incorporating a cheap disposable component, containing the product, which can be changed in minutes when a batch changeover is called for.

CCL claim that there is no need to take these pumps off-line for cleaning, as they can be opened up and the contaminated components removed in one piece. The cheap, disposable components are quickly replaced with clean or pre-sterilised ones, and production can be restarted within a few minutes. Meanwhile, the contaminated parts can be disposed of by incineration or other means with no risk to operatives and just as importantly with minimum pollution.

All parts in contact with the product are easily accessible, cheap, disposable, can be supplied sterile. Auxiliary equipment such as tubing and delivery nozzles are also disposable and replaceable in minutes. By contrast, equipment on a conventional filling lines may involve up to four hours of downtime.

The stock tank incorporates a disposable liner, and a diaphragm transfer pump which also has disposable contact parts, is used to carry the product from here to the accumulator reservoir, which similarly has a cheap disposable container

Additionally, the accumulator can supply the liquid at a preset pressure, a major benefit when dosing high viscosity products, as it prevents cavitation in the dosing pump, a problem experienced particularly at faster packaging line speeds.

Replacing a break tank, the accumulator maintains the supply of liquid to the dosing/metering pump, which, like the diaphragm pump, contains cheap disposable product contact components. The equipment on the process line is connected using disposable tubing and disposable couplings.

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