Litre Meter Increases Mass Thermal Options with New High Performance Instruments from Sierra

28 November 2012

Two new high-performance products from Sierra Instruments, billed as the most accurate thermal mass flowmeters available, are now available in the UK from Litre Meter.

The 640 insertion and the 780 inline meters are based on Sierra’s new QuadraTherm™ technology which introduces the first four-sensor thermal mass flow meter design. The meters comprise three precision platinum temperature sensors and one patented DrySense™ mass velocity sensor, which uses a proprietary swaging process that eliminates all air gaps between the heated velocity sensor and the tubular probe sheath. This results in maximum sensitivity, reproducibility, immunity to cracking and shifting over time to greatly improve accuracy.

The instruments measure all thermal heat transfers occurring and work with a proprietary algorithm set to quickly solve the first law of thermodynamics (for thermal dispersion technology) for each mass flow data point. They measure and then calculate stem conduction and all other unwanted heat loss components, subtracting them to calculate the gas mass flow rate from the remaining forced convection (gas mass flow) component.

This iTherm™ algorithm is also the ‘brain’ behind the flowmeter’s capability to change gas (Dial-A-Gas) and pipe size (Dial-A-Pipe) in the field. At the same time the meter can be updated via an internet connection to the most up-to-date gases in Sierra’s proprietary iTherm™ Gas Library.

The 640s achieves an accuracy of +/- 0.75 per cent of reading above 50 per cent of full scale. The instrument measures up to 60,000 sfpm (305 smps) and features a 100:1 turndown. Its small diameter 3/4" (19.1 mm) probe insertion point means easy process installation.

The 780s inline version achieves accuracy of +/- 0.5 per cent of reading making it the most accurate thermal meter in the world. The 780i also measures up to 60,000 sfpm (305 smps) and features a 100:1 turndown.