Sierra Instruments' QuadraTherm 640i/780i Thermal Mass Flowmeter Series

The QuadraTherm 640i/780i Thermal Mass Flowmeter Series marks a breakthrough in thermal dispersion technology. With its sensor design advancements, coupled with a proprietary iTherm “Brain,” the 780i inline version achieves gas mass flow rate measurement accuracy of ±0.5% of reading above 50% of the full scale (air), making it the most accurate thermal meter in the industry. At the heart of the 640i/780i is its revolutionary patented QuadraTherm sensor and proprietary iTherm algorithm set. QuadraTherm introduces four sensors—three precision platinum temperature sensors and one patented, no-drift DrySense mass velocity sensor. The QuadraTherm sensor isolates forced convection by calculating and then eliminating unwanted heat-transfer components, such as sensor stem conduction. QuadraTherm and iTherm calculate stem conduction and all other unwanted heat loss components, subtract them out, and then compute the mass flow rate from the remaining forced convection component.