Thermodynamic Flow Meter

Accurate and low cost flow metering is a major concern for pumps and pump systems.

The thermodynamic flow meter has significant advantages over ‘conventional’ flow meters:-

• The flow rate is obtained from well-characterised temperature, pressure, and power sensors

• The calibration of these sensors can be checked on-site, and uncertainty is well characterised

• Each pump has its own flow meter (and efficiency measurement). The operating points are known, and it is possible to assess and improve the energy efficiency and MTBF (Mean time Between Failures) for every pump of the pump system

• Measures the actual mass flow over the complete pipe cross-section, and is independent of velocity profile, pipe condition, cavitation, and air entrainment

• Lower cost than alternatives for retrofitting to existing pump stations

• Low construction and pipework costs for new pump stations

It is cost-effective to equip every pump in a pump station with condition monitoring of each pump, with the MicroPM™ Pump Monitor.

Consider the alternative of the ‘conventional’ station flow meter:

• A station flow meter cannot assess the performance of individual pumps in combination with other pumps, at the operating point

• There is no clear path to improve pump system performance

• Flow meter accuracy is affected by air entrainment, cavitation, operating point, build-up on pipes and sensors, and pipe work configuration (often requiring long lengths of straight pipe before and after the flow meter).

• It is difficult to assess the accuracy of the flow meter. It may typically be 5% to 10%, due to a number of site-dependent errors of unknown magnitude. The user is reliant on the manufacturer’s calibration, often carried out many years ago and under completely different conditions. On-site calibration checks have been developed for some types of meter, but accuracy is unlikely to be better than 5% (some manufacturers are more optimistic than others).