Severn Trent Services chooses Watson-Marlow Bredel pumps for reliable on-line sampling

Reliability under all operational conditions and the ability to deliver a consistent, volumetrically accurate sample over long periods were the key factors in the selection by Severn Trent Services of Watson-Marlow Bredel peristaltic pumps for fitting into their Series 1000 ISE range of on-line water quality monitors.

Series 1000 ISE (Ion Selective Electrode) monitors can be configured for monitoring ammonia, fluoride or nitrates, with the 504MC2 twin-channel pumps used for continuous delivery of two sample streams to the ion selective electrode. Sampling flow is over the range 200 to 500 ml/min at a minimum pressure of 0.34 bar and a maximum of 0.69 bar; sampling temperature is from 0C to 50_ C. Sample and electrode are temperature controlled by an integral mechanical heat exchanger.

By using a peristaltic pump, the sample is contained within the tube throughout the entire pumping process. With no other contact components, there is no risk to the integrity of the sample by contamination from external sources, while the straight through flow path and smooth pumping action obviate any possibility of sample degradation through shearing or agitation.

Watson-Marlow Bredel 504MC2 twin-channel pumps have been used by Severn Trent Services for approximately two and a half years. The pumps are fitted with colour coded manifold tubing, the largest bore tube providing flow rates up to 0.48 ml/rev.