Throwaway ideas

26-Nov-2007 - Last updated on 15-Mar-2017 at 05:12 GMT

Related tags Pump Pumps

In an environmentally conscious age, disposable pumps might seem odd. But the idea is not as barmy as it seems. Michelle Knott reports

The idea of disposable pumps may sound barmy at first. After all, doesn't the throwaway society lie behind some of our biggest ecological problems, placing unsustainable demands on resources and spawning a rash of festering landfills? But there are times when disposability is a virtue, not only because it's convenient, but also because it can benefit the environment.

Consider the impact of the water, chemicals and energy used for cleaning in the food industry. If a way can be found to reduce or even eliminate them by using disposable components, it might deliver a significantly greener solution.

"When you're washing contaminants out of your equipment you're actually magnifying the problem by the volume of water you've used, because you've now got to dispose of it. It's a particular concern in the pharmaceutical industry where you may be talking about powerful toxins, but the same principle applies in the food industry," says Ted Coulson, who has set up a company, CCL Concepts and Developments, to develop his own disposable answer to the problem (see diagram above).

Coulson is not alone in believing that disposable pumps are the way to go. At least two other companies - PDD Innovations and AC Engineering - are also developing novel pumps based on disposable components. Although none of the ideas are commercialised as yet, they're all attracting the kind of interest they need to make their way to the market.

Disposable pump backing

For example, London-based venture capital fund The Capital Fund, last year announced that it was backing PDD's disposable pump to the tune of £250,000.

PDD is an innovation consultancy and usually encourages large companies to come up with new ideas and develop them. The idea for the disposable pump was unusual in emerging from the PDD engineering labs without prompting from an industrial partner. The company is promoting it under the trading name of Quantex.

"It was invented by engineers at PDD in 2004," says director Peter Ross. "We saw an opportunity there and realised that there could be all sorts of uses for this."

Meanwhile, Jerusalem-based AC Engineering has already got the tools to mass-produce its disposable pumps and is attracting the scrutiny of the original equipment manufacturing market. "We have a great interest with one large manufacturer of food dispensing machines," says president and chief executive Carmeli Adahan. "The pumps are tooled for several capacities, including four litres per minute and 35l/min, but they can be scaled to obtain any desired flow."

Independent technology transfer agency, RTC North, has taken up the charge on behalf of CCL, and Coulson is cautiously optimistic about the reaction from potential manufacturers.

"Everybody we've approached has seen the need for it," he says. "No one's found fault with the idea, but there's always a reluctance to put in the investment for such a new idea."

Coulson's idea comes in two versions. The first is a diaphragm pump fitted with a disposable liner, which could pump liquids out of a tank or drum at a constant head. The pumping chamber would be subjected to a vacuum to ensure that the liner re-inflates properly after each discharge cycle.

Getting bladdered

The second version is a syringe coupled to a vacuum chamber filled with two inflatable bladders (see diagram on previous page).

The first bladder is connected directly to the syringe and inflates and deflates in line with the movements of the syringe plunger. Combined with the surrounding vacuum, this alternately draws process fluid into the second bladder and discharges it, with the flow of process fluid in and out of the chamber controlled by a pair of pinch valves. This delivers an extremely precise dose, which is determined by the syringe.

It should take less than five minutes to change the liners over, says Coulson: "With normal cleaning procedures the cleaning times can exceed the plant running time if you're not careful, especially if you have lots of short production runs. We hope to start by manufacturing the liners from materials that would suit the most common dosing applications, but they could be made from a range of different polymers. They could be supplied pre-sterilised and certified and could be disposed of after use without diluting the contaminants."

With the search still on for a manufacturing partner, the idea hasn't been tested on an industrial version yet, so Coulson is unsure about the pressures that his pumps might be able to manage. "The bags would probably be sealed from two sheets and that seal could be a weak point under pressure," he concedes.

"But if you were putting jam into doughnuts you wouldn't need a high pressure and most products are like that." On the other hand, the CCL concept is the only one of the three disposable contenders that should be able to cope happily with abrasive materials, provided the pumps are fitted with the right liner.

Disposable plastic pump heads

Rather than CCL's disposable liners, the pump designs from PPD and AC Engineering both rely on low-cost disposable plastic pump heads.

"Our design is like a square peg in a round hole," says PPD's Ross. "You slot it on to a motor but the pump part is entirely disposable and can be changed in seconds." The Quantex pump was developed initially for the medical sector. In food, it is likely to be used in precision dosing applications, such as additives and flavourings.

The pump uses a simple, two-piece arrangement of rotor and stator that creates a series of chambers that move the fluid around the pump. When it reaches the output port, the fluid is squeezed out by an elastomeric diaphragm. Delivery rates currently range up to four or six litres per hour or down to less than one millilitre, with an accuracy of ±3% across the entire range. The components are injection moulded from recyclable, low-cost polyethylene, but a range of different polymers could be used to suit different applications.

"Each application has got to be explored individually, but the one difficulty seems to be abrasives. So things like ketchup, soap or honey are fine but toothpaste isn't," says Ross.

One possibility is "pumped packaging" and Ross says PPD is already working with a potential manufacturing company to explore this option. In this set-up, suppliers fit the Quantex pumps in place of bottle caps, allowing the contents of the package to be machine pumped. According to Ross this could be used for hygienic dispensing in industrial and medical settings and also in novel consumer goods. For example, smart dishwashers and washing machines could be designed to detect the level of dirt in the wash water and use pumped packaging to vary the dose of detergent to match, cutting down on the use of chemicals.

AC Engineering's sanitary pumps offer higher flow rates, potentially reaching 500l/min. The pump head is a type of scroll pump, which comprises a sealed plastic chamber with internal rotating parts that push the fluid through at a constant pressure. Not only does the design eliminate pressure spikes, it also requires no external lubricants or valves.

The disposable parts need to provide good wear and chemical resistance, and must be dimensionally stable so they don't become distorted over time or as a result of temperature fluctuations. They also need to comply with US Food and Drug Administration requirements for food-grade applications and be cheap enough not to price the disposable pump heads out of the market. The company therefore opted for a specialised polyphenylene sulphide (PPS) glass fibre-reinforced compound with internal polytetrafluoroethylene lubrication.

Licence negotiations

"We are negotiating a licence with one of the leading world pump manufacturers," says Adahan. "The pumps have been tested and approved by three potential large customers."

AC Engineering sees peristaltic pumps as the main competitors to its scroll pump, but argues the new design will have several advantages. According to the company, its pump heads will last longer than peristaltic pump tubes and won't burst. It also claims that the scroll pumps are more stable during warm up, offering precision delivery right away where a peristaltic tube might need a 20-minute breaking in period. The scroll pumps are also designed to offer higher throughputs in a smaller size.

The idea of disposable pumps is certainly attractive. They could do away with expensive cleaning regimes and the environmental impact that goes with them, as well as giving users the ability to change over from using one fluid to another in minutes or even seconds. Unfortunately, it will take time for any of these pumps to hit the market. So for now it's a question of 'watch this space'. FM

Piston perfection for viscous fluids

Transferring thick, high viscosity fluids such as purees, pastes, creams, syrups and gels in the food and brewing sectors presents unique pumping problems. However, air-operated piston pumps are ideally suited to these types of application.

CSF piston pumps from Pump Engineering have the added benefit of being available as quick-strip versions, which can be easily dismantled for simple and effective cleaning, without the need for tools.

The pumps can be supplied as long versions for drum emptying or short versions for bottom discharge vessels or for applications where wall-mounting is required. They ensure improved flowrate and increased efficiency.

Contact: Pump Engineering; Tel: 01903 730900

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