Sierra Instruments QuadraTherm 640i / 780i Thermal Mass Flow Meter
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.
- Features & Benefits
- Applications
- Product manuals
- Product specs
- 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)
- Custody transfer
- Flare gas measurement (with qMix RealTime FMS option)
- Wastewater treatment and digester gas
- Compressed air audits and energy management
- Hazardous-area process measurement
- Facilities management
- General industrial process control
| Gas / Media | All inert & non-condensing clean gases; flammable gases (methane, propane, hydrogen, digester & natural gas) |
|---|---|
| Accuracy | ±0.5% of reading (inline); ±0.75% of reading (insertion) |
| Flow / Velocity Range | 0.03 to 305 SMPS (0.1 SFPS to 60,000 SFPM) |
| Turndown | 100:1 |
| Line Sizes | Up to 72" (182 cm) |
| Process Temperature | -40 to 392 °F (-40 to 200 °C); HT option to 750 °F (400 °C) on 640S |
| Process Pressure | 500 psia (34.5 bara) on -1 NAA; 300 psig (20.7 barg) max on agency-approved -2/-3 |
| Wetted Materials | 316 / 316L SS; Pt/Ir velocity sensor |
| Outputs | 4–20 mA (flow, temperature, optional pressure) |
| Communication | Modbus RTU, HART |
| Power Supply | 100 to 240 VAC |
| Enclosure Rating | NEMA 4X (IP66); explosion-proof |
| Approvals | cFMus, ATEX, IECEx |
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