Sierra FlatTrak 780S In-Line Thermal Gas Mass Flow Meter with Flow Conditioning

Overview

The Sierra FlatTrak 780S is an in-line thermal gas mass flow meter that combines the thermal sensor used in Sierra’s immersible meters with a flow body containing a built-in flow conditioner. The conditioner eliminates velocity profile distortions, swirl and temperature stratification in the gas stream, and it reduces the amount of straight upstream piping needed for accurate measurement. The same microprocessor-based transmitter as the SteelMass series provides flow measurement, range adjustment, validation and diagnostics.

Gas skids, burner trains, compressor packages and plant utility headers in Oman often have elbows, valves and reducers close to the meter location, which makes a conventional insertion meter hard to apply. Seven Star LLC supplies the Sierra FlatTrak 780S with engineering support in Muscat, so project teams can choose flow body size, connection and approvals and receive the meter with the correct gas calibration.

Flow Conditioning Principle

Thermal mass meters are sensitive to the velocity profile of the gas, because the heat carried away from the sensor depends on local velocity. The Sierra FlatTrak 780S places two perforated plates in series upstream of the sensor, and this built-in flow conditioner flattens the profile before the gas reaches it. Sierra’s insertion meter datasheet notes that flow conditioning plates reduce upstream requirements to as little as 2 diameters, where an insertion probe would need 15 to 40.

The datasheet compares the requirement with an ISO 5167 orifice plate: after a single 90 degree elbow the FlatTrak needs 1 diameter upstream compared with 28 for an orifice plate, after a control valve 3 diameters compared with 32, and after two 90 degree elbows in different planes 5 diameters compared with 62. No downstream straight length is required. The thermal sensor itself uses Dry-Sense technology, which is designed to eliminate drift.

Engineering Design of the Sierra FlatTrak 780S

Flow bodies are available from 1/4 inch up to 8 inch in 316L stainless steel, with carbon steel bodies offered in some sizes. Connections include NPT, 150 lb ANSI flanges and DN flanges. The mechanical design pressure is 500 psig (34.5 barg) for NPT connections and 230 psig (15.9 barg) for 150 lb or PN16 flanges at ambient temperature, falling to 185 psig at 250 °F and 155 psig at 450 °F. The transmitter is housed in a hazardous-area location enclosure rated IP66 or a NEMA 4X (IP65) enclosure, both in powder-coated cast aluminum.

Power is 18 to 30 VDC or 100 to 240 VAC, and outputs are linear 4 to 20 mA, 0 to 5 VDC or 0 to 10 VDC, with Modbus RTU and a pulse output available as options. The configuration screen offers adjustable full scale, response time from 1 to 7 seconds, correction factor, high and low alarms and a seven-digit totalizer. A two-line, twelve-character backlit display is optional, and Smart Interface software supports guided validation of the Sierra FlatTrak 780S.

Key Features

The Sierra FlatTrak 780S provides the following capabilities:

• Built-in flow conditioner that removes velocity profile distortions caused by upstream disturbances.
• Direct mass flow monitoring without separate temperature and pressure transmitters.
• Accuracy of plus or minus 1 percent of reading plus 0.5 percent of full scale, with repeatability of plus or minus 0.2 percent of full scale.
• Patented Dry-Sense technology that eliminates sensor drift, with a one-second response to flow changes.
• Flow bodies from 1/4 inch to 8 inch with NPT, ANSI flange and DN flange connections.
• Fully guided field validation of the meter electronics and sensor.
• FM, ATEX and CSA hazardous-area approvals and CE approval.
• Gas temperatures from −40 to 350 °F (−40 to 177 °C), with a remote enclosure required above 149 °F (65 °C) for ATEX units.

Industrial Applications

The Sierra FlatTrak 780S is a strong fit for compact gas systems: fuel gas to burners and turbines, compressed air and nitrogen headers, biogas and digester gas lines, and process gases on skid-mounted packages. In the Sultanate of Oman such skids are common at oil and gas production sites, gas treatment plants, power stations and industrial estates in Sohar, where space for long straight runs is limited and measurement of fuel gas consumption by mass supports energy efficiency and reporting.

Because the flow body is part of the instrument, the meter is calibrated as a complete unit, which helps repeatability. Seven Star LLC supplies the Sierra FlatTrak 780S alongside related gas measurement equipment such as the Sierra Instruments QuadraTherm 640i thermal mass flow meter, the Elster Q.Sonic plus ultrasonic gas flow meter and the Elster gas-net F1 flow computer for gas measurement.

Technical Specifications

The table lists data from the manufacturer datasheet for the Sierra FlatTrak 780S. Confirm flow body size, connection and approvals against the ordering chart.

Request a Quote for Sierra FlatTrak 780S

Send an RFQ for the Sierra FlatTrak 780S to the Seven Star LLC instrumentation division in Muscat with the gas type, line size, flow range, operating pressure and temperature, and approval needs. We will confirm the flow body and connection, arrange supply to Oman and the GCC, and include the manufacturer’s Sierra FlatTrak 780S datasheet with the quotation so your engineers can review all ratings.