Sierra Instruments QuadraTherm 640i Thermal Mass Flow Meter

Overview

The Sierra Instruments QuadraTherm 640i is an insertion-style thermal mass flow meter engineered for precise air and gas measurement in demanding industrial environments. Built around Sierra’s patented DrySense sensor technology and Quad Sensor architecture, the QuadraTherm 640i delivers gas mass flow accuracy that rivals Coriolis-class instruments while retaining the low installed cost and simple insertion mounting of a traditional thermal meter. Its combination of accuracy, sensor durability, and field-serviceable design has made the QuadraTherm 640i a standard choice for compressed air auditing, combustion air measurement, and emissions monitoring programs.

Backed by manufacturer datasheet documentation, Seven Star LLC proudly supplies the QuadraTherm 640i thermal mass flow meter to industrial plants, utilities, and engineering contractors across the Sultanate of Oman and the wider GCC. Seven Star LLC supplies the Sierra Instruments QuadraTherm 640i on request with the manufacturer datasheet and regional technical support for buyers in Muscat and beyond, with lead time confirmed at quotation.

Operating Principle

The Sierra Instruments QuadraTherm 640i measures gas mass flow using the thermal dispersion principle: a heated sensing element is held at a constant temperature differential above the process gas temperature, and the electrical power required to maintain that differential is directly proportional to the mass flow rate passing over the sensor. The QuadraTherm’s Quad Sensor design uses four measurement elements rather than the traditional two, cross-checking readings in real time to detect sensor drift, fouling, or damage long before it would affect accuracy on a conventional thermal meter.

The patented DrySense sensor coating keeps moisture and particulate from settling on the sensing elements, which is the primary cause of long-term drift in thermal flow technology. Because the QuadraTherm 640i measures mass flow directly, there is no need for separate temperature and pressure compensation calculations, and the field-configurable qMix gas mixing software allows the meter to be recalibrated for a different gas composition without removing it from the process line. The practical result is a meter that holds its factory accuracy for years, requires minimal field intervention, and provides an early warning of sensor health issues before they cause a bad reading.

Engineering Design of the Sierra Instruments QuadraTherm 640i

The Sierra Instruments QuadraTherm 640i is built around a rugged stainless steel insertion probe and a robust cast aluminum electronics enclosure rated to IP66, with ATEX certification available for installation in hazardous-area gas and biogas applications. The probe length is selected to match the pipe or duct diameter, and a compression fitting allows the sensor to be inserted and positioned at the correct measurement point without cutting the line, keeping installation costs far below those of a full-bore inline meter.

The onboard backlit display and integral keypad allow flow rate, totalized volume, and diagnostic data to be read and configured directly at the meter, while a full suite of outputs, including 4-20 mA, Modbus RTU, and digital pulse, support integration into plant control and monitoring systems. Terminal compartments are physically separated from the sensor electronics to protect the low-level signal path from electrical noise, and the meter’s field-validation capability lets technicians verify calibration integrity in place, without pulling the probe from the process for bench recalibration.

Key Features

The Sierra Instruments QuadraTherm 640i key features combine measurement stability with practical field serviceability. The Sierra Instruments QuadraTherm 640i offers the following:

• Delivers accuracy of ±0.75% of reading above 50% of full scale, with repeatability of ±0.15%, rivaling Coriolis-class mass flow performance.
• Uses patented DrySense sensor technology to resist moisture, particulate fouling, and long-term drift common to conventional thermal flow sensors.
• Employs Quad Sensor Technology with four measurement elements for continuous self-diagnostic cross-checking of sensor health and accuracy.
• Supports field-based gas composition changes through qMix software without requiring the meter to be removed for recalibration.
• Provides in-situ field validation, allowing technicians to confirm calibration accuracy without pulling the probe from the process line.
• The Sierra Instruments QuadraTherm 640i offers 4-20 mA, Modbus RTU, digital output, and RS-232 communication for flexible integration into SCADA and building automation systems.
• Is available with ATEX certification and IP66 enclosure protection for safe operation in hazardous and outdoor gas measurement environments.
• Backed by a lifetime sensor warranty and Boiler MACT certification under EPA 40 CFR for area and major source boiler compliance reporting.

Industrial Applications

The Sierra Instruments QuadraTherm 640i is widely deployed for compressed air system auditing, combustion air measurement, biogas and flare gas monitoring, and wastewater aeration blower control, where accurate low-pressure gas flow data drives both energy savings and regulatory compliance. In the Sultanate of Oman and across the GCC, power generation plants and industrial facilities rely on thermal mass flow meters like the QuadraTherm 640i to optimize combustion air ratios and reduce compressed air energy waste, both of which are increasingly tied to national energy-efficiency initiatives.

Working closely with plant engineers in the region, Seven Star LLC distributes the QuadraTherm 640i to district cooling plants, oil and gas processing facilities, chemical plants, and industrial operations within the Sohar and Salalah economic free zones, where flare gas and vent gas metering support both environmental reporting and process safety. Semiconductor fabrication, food and beverage processing, and municipal wastewater treatment operators across the region also depend on the QuadraTherm’s stable, drift-resistant readings to maintain accurate mass balance and emissions accounting.

Technical Specifications

The table below summarizes the core technical specifications of the Sierra Instruments QuadraTherm 640i, confirming why the Sierra Instruments QuadraTherm 640i is specified across regional gas measurement projects.

Request a Quote for Sierra Instruments QuadraTherm 640i Thermal Mass Flow Meter

Seven Star LLC invites industrial facilities, EPC contractors, and utility procurement teams across Oman and the GCC to submit a formal RFQ for the Sierra Instruments QuadraTherm 640i thermal mass flow meter. Lead time is confirmed at quotation, and our instrumentation division can provide the full technical datasheet, probe-length sizing, and qMix gas configuration support to match your exact application. With fast quotation turnaround, Seven Star LLC supplies the equipment on request with dedicated local technical support — contact our team today to request a quotation or arrange a technical consultation.

Browse the full Sierra Instruments range or see more Flowmeters products supplied by Seven Star LLC in Oman and the GCC.