Ultrasonic Flowmeters Help to Keep Pure Water on the Move


Ongoing, reliable flow measurement as part of their water quality monitoring system, is an important requirement at Glaxo Smith-Kline’s manufacturing plant in Harlow, where a significant amount of WFI, ‘Ultra Pure Water’ is used.

To eliminate the potential for purification faults, which could be caused by bacteria and foreign bodies being present, the water needs to be kept circulating in the ring main pipe work at a constant 85°C - 90°C temperature. When the laboratories have a requirement for water, it is fed through a chiller and then delivered to the lab at a constant 15°C.

However, the turbine meters originally installed as part of the water monitoring system caused problems as a result of bearing failure. The problem with turbines in these applications is that they need the fluid being measured to be reasonably lubricating to operate effectively and ultrapure water is extremely ‘dry’.

The solution to the problem was to install non-contact, clamp-on ultrasonic meters and these were supplied by flow measurement specialists FLOWLINE. Thanks to their non-contact, non-invasive ultrasonic principle, Glaxo Smith-Kline were able to install the Minisonic ultrasonic meters without the need for any process shut-down. However, Flowline had to overcome the problem of measurement errors that were occurring with another clamp-on flowmeter, caused by the water being chilled prior to being delivered to the point of use. Rigorous testing of the system was carried out and this proved that the Minisonic flow meters were capable of handling the fluctuating temperatures, without inducing errors on the measurement.

Minisonic non-intrusive flow meters were selected by Glaxo Smith-Kline for their range-ability and ease of installation, helped by the fact that they could be easily retro-fitted onto existing pipe work without flows being interrupted or by-passed. Also, installation could be easily checked courtesy of the in-built meter diagnostics.

The versatile Minisonic system can be used on pipe diameters ranging from 10mm up to 3.3 metres (up to 10 metres on some systems) and is effective on most liquids, including those which are non-conductive. The unit’s non-invasive, external probes are simply clamped on to the pipe to facilitate quick installation and immediate measurement, while set-up and operation can be performed either by keypad or external software.

Other features and benefits include all new digital processing functions which use multiple processors resulting in faster response times. Also available as an optional extra depending on application specifications, are a range of portable systems which provide a choice of configurations from previously stored data from other sites, a battery life indicator and an integral data logger which provides over 6 months capacity at 2 minute intervals.

The Minisonic 801 provides a measuring accuracy of up to ± 1.0% of reading and is suitable for a wide range of control applications. For example, monitoring flows in all water and waste processes, pump testing, various oil products either refined or crude, petrochemical and food industries, or wherever fixed or portable, highly accurate and reliable flow metering is an important requirement.

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