A small manufacturing company in Malvern is making a success of producing innovative quality assurance equipment for the contact lens industry based on peristaltic pump technology from Watson-Marlow.
There cannot be many objects more awkward to measure than contact lenses - yet this is precisely the feat achieved regularly by hundreds of Optimec customers. Optimec equipment measures contact lens by suspending them in a saline solution, which provides enough surrounding strength for measurements to be collected.
Light is shone through the solution/lens, and then through an optical projector system that generates a magnified image of the contact lens on a screen. This is the Optimec JCF model.
The problem faced by Optimec was that the light source raised the temperature of the saline solution, which in turn caused the dimensions of the contact lenses to drastically alter. The answer was to ensure that lenses were measured at a standard temperature, in this case 20 Degrees Celsius.
In response to this need Optimec designed the TC20 model. The TC20 model was initially designed using an in-house manufactured diaphragm pump. This was found to be difficult to manufacture and set up. The solution was met admirably by choosing the 102R single channel peristaltic pumpheads from Watson-Marlow's OEM pump range.
"Today we use the 102R and Pumpsil silicone tubing in the TC20 to pump saline solution from the lens analysis wet cell through a cartridge filter and then through a heat exchanger where it is cooled or heated before being pumped back to the lens analysis cell," says Technical manager Colin Bryant. "The use of the Watson-Marlow 102R pumphead means that the TC20 unit pumping requirement is met by a good quality and reliable OEM pumphead."
Another product in the Optimec portfolio that uses the Watson-Marlow 102R peristaltic pump is the JCF/F, in which the analysis cell uses the 102R single channel peristaltic pumphead to re-circulate the saline to remove any airborne contaminants from the analysis cell.
"The original design of these units specified a special diaphragm pump that we designed and assembled ourselves," explains Mr Bryant. "However, the pump was extremely awkward to build and set-up and we simply reached a point where we didn't want to continue. When we began to investigate alternative options, a peristaltic pump was the obvious solution. The cost savings in build time alone were vast. Add this to its off-the-shelf availability, exceptionally low maintenance requirements and the zero contamination factor, and it's easy to see the benefits it has provided."
Optimec units allow the accurate measurement of contact lens base curve optic radius, centre thickness and overall diameter. Visual inspection of both front and back lens surfaces for splits and inclusions is also possible, along with close-up viewing of the lens edge.
Optimec used its first Watson-Marlow peristaltic pump in 1988 and today the company has delivered over 450 systems incorporating 102R pumps to a multitude of quality control departments at various contact lens laboratories and research facilities.
"In terms of our systems in the field, the 102R pump has performed admirably," says Mr Bryant. "As long as the customer adheres to our simple procedures, the pumps will go on for years and years."
In peristaltic pumps, fluid is drawn into a tube and forced through it by the action of a number of rollers squeezing and releasing the tube. Because nothing but the tube is ever in contact with the fluid, there is no risk of the fluid contaminating the pump, or of the pump contaminating the fluid.
The design also prevents backflow, so eliminating the need for check valves when the pump is not running. The Watson-Marlow 102R pumphead accepts tubing in a number of different materials including platinum-cured silicone and long life, chemical resistant Marprene, to achieve continuous flow rates up to 106ml/min and intermittent flow rates up to 212ml/min. It is also available with faceplate-mounted OEM drives with fixed or variable speed drives.