When a successful laboratory equipment manufacturer wanted a pump to help it manufacture sample containers for the water industry, it was the peristaltic technology from Watson-Marlow that secured the order ahead of more 'conventional' pump suppliers.
Established in 1988 near Bath, Aurora Scientific has flourished, and today employs 20 people to assist in the manufacture of water quality testing systems. Among the products that make up the kit are sample containers (similar to test tubes) that are used to analyse water for a wide variety of parameters such as metals, cyanide and total organic carbons.
To achieve this, the containers are first dosed with aggressive chemical reagents, such as acids. Aurora has designed a special purpose machine to handle the production process of the test kits and required a pump that could cope with the aggressive chemicals and accurate dosing requirements.
Peristaltic pumps have no valves, seals or glands, and nothing but the tube touches the fluid, eliminating the risk of the pump contaminating the fluid, or the fluid contaminating the pump. It is therefore also ideal for aggressive fluids such as those processed by Aurora Scientific. Simple to install, easy to use and quick to maintain, the technology works by drawing fluid into the tube where it is forced forwards by a number of rotating rollers and eventually expelled. The complete closure of the tube by the rollers gives the pump its positive displacement action, preventing backflow and siphoning and eliminating the need for the check-valves and associated pipe work required by other pump types.
Following a demonstration of a Watson-Marlow peristaltic pump. Aurora Scientific was duly convinced and subsequently purchased a high accuracy 520Di dispensing pump at the beginning of 2005. The 520Di uses process signals fed back from the Aurora production equipment to begin dosing when required.
"It was immediately apparent that peristaltic technology suited our production applications," explains Brian Hepburn, proprietor at Aurora Scientific. "Moreover the pump also had no problem meeting the high dosing accuracy and repeatability requirements we had. We wanted to invest to increase our range of specialist products offered to the water industry. One way to do this was to duplicate our existing dosing facility, which uses a syringe pump, but introduce more automation into the process. The 520Di provided the solution."
The Watson-Marlow 520Di combines high levels of functionality with an on-screen menu, easy-to-use tactile membrane keypad and an alphanumeric display. With no impellers, vanes or valves, the 520Di dispenses delicate fluids without damage or degradation. Suspended solids also present no problems. It comprises a brushless DC motor with 3500:1 speed control and full RS485 control via serial communications.
Among its many benefits are: accuracy to within ±0.5 per cent; the ability to dispense 100ml in 1.4 seconds; a soft-start 'ramp' to reduce splashing; a non-drip function to eliminate drips at dose end; dial-up flow rates from 4 microlitres/min to 4.4 l/min; dispensing by keypress or a remote footswitch/handswitch; the ability to store up to 50 dispensing programs; and a three year comprehensive warranty.
"Since installation the 520Di pump has worked flawlessly, helping to produce thousands of sample containers every week," concludes Mr Hepburn. "We've had no issues whatsoever. It's extremely user-friendly and simple to program, and it has successfully supplemented and replaced some of our existing equipment. We're very pleased with both the product and the level of service and support offered by Watson-Marlow."