Sierra Instruments QuadraTherm 640i / 780i Thermal Mass Flow Meter

The Sierra Instruments QuadraTherm® 640i (insertion) and 780i (in-line) are the highest-accuracy thermal mass flow meters Sierra manufactures — the 780i achieves ±0.5% of reading and the 640i achieves ±0.75% of reading above 50% of full scale. Both meters are built on Sierra’s patented four-sensor QuadraTherm platform: three platinum temperature sensors plus one no-drift DrySense™ mass-flow velocity sensor backed by a lifetime warranty.

Onboard qMix™ software lets operators create or change gas compositions in the field without sending the meter back for recalibration, while Dial-A-Gas® and Dial-A-Pipe® technologies change gas selection and pipe size on demand. Each meter is Boiler MACT certified for both area-source boilers (40 CFR 63, subpart JJJJJJ) and major-source boilers (40 CFR 63, subpart DDDDD) and GHG-certified to EPA 40 CFR Part 98 — targeted at custody transfer, flare gas, wastewater treatment, hazardous-area, and general process control applications.

Industry-leading accuracy — ±0.5% of reading (780i in-line), ±0.75% of reading (640i insertion) above 50% of full scale
Patented four-sensor QuadraTherm® technology — three platinum temperature sensors + one DrySense™ velocity sensor
No-drift DrySense™ sensor with lifetime warranty
qMix™ gas mixing software — create custom gas mixtures in the field without factory recalibration
Dial-A-Gas® and Dial-A-Pipe® — change gas and pipe size in the field
Reduced straight-run requirements with built-in flow conditioning (780i: 3D up / 0D down; 640i: 1D up / 0D down)
ValidCal™ Diagnostics — field calibration validation and meter diagnostics
Multivariable outputs — mass flow rate, temperature, and pressure
Boiler MACT certified (40 CFR 63 subparts JJJJJJ and DDDDD)
Greenhouse Gas (GHG) certified to EPA 40 CFR Part 98 — CH4, N2O, SF6, HFCs, PFCs, CO2
Powered by the proprietary Raptor OS™ operating system (formerly qTherm)
High flows up to 60,000 sfpm (305 smps)