Sierra QuadraTherm 780i In-Line Thermal Mass Flow Meter

Name: Sierra QuadraTherm 780i Thermal Mass Flow Meter – Datasheet
Brand: Sierra Instruments
SKU: 780i

Description

An in-line thermal mass flow meter with built-in flow conditioning for air, natural gas and gas mixtures

The Sierra QuadraTherm 780i is the in-line version of the QuadraTherm thermal mass flow meter family, supplied in a 316 stainless steel flow body with an integral flow conditioner. It measures mass flow, temperature and, with the VTP option, pressure. Sierra states an accuracy of plus or minus 0.5% of reading above 50% of full-scale flow for the in-line version, 100:1 turndown and a velocity range of 0 to 60,000 sfpm (305 smps). The four-sensor design uses three platinum temperature sensors and one DrySense mass velocity sensor, and the Raptor 2 operating system applies a heat-transfer model to remove effects such as stem conduction and natural convection.

Technical specifications

Parameter	Specification
Parent models	780i-VT (mass flow and temperature); 780i-VTP (adds pressure measurement, extra 4-20 mA output, sensor up to 500 psia / 34.5 bara)
Gases	Inert and non-condensing clean gases; flammable gases including methane, propane, hydrogen, digester gas, natural gas; corrosive gases compatible with 316 SS, 316L SS and Pt/Ir
Mass flow accuracy (in-line)	Plus or minus 0.5% of reading above 50% of full scale; plus or minus 0.5% of reading plus 0.5% of full scale below 50%
Repeatability and response	Flow plus or minus 0.15% of full scale; 3 seconds to 63% of final value; turndown 100:1
Temperature and pressure accuracy	Gas temperature plus or minus 1 degree C; gas pressure plus or minus 1.0% of full scale
Gas temperature range	-40 to 200 degrees C (-40 to 392 degrees F)
Pressure limits	NPT: 500 psia (34.5 bara) NAA only, 300 psig (20.7 barg) for cFMus or ATEX/IECEx; ANSI 150 flanges per class rating, 230 psig at -20 to 100 degrees F
Wetted materials	316 SS, 316L SS and Pt/Ir velocity sensor; Viton for the VTP pressure option
Process connections	NPT 1/2 to 8 inch; ANSI class 150 flange 1/2 to 8 inch; DN25 to DN200 PN16 and DN25 to DN80 PN40 flanges, as listed in the ordering table
Outputs	4-20 mA flow, 4-20 mA temperature, 4-20 mA pressure (optional), alarm contact SPST/opto relays, totalised pulse output
Communications	Modbus RTU or HART (optional), RS-232 or USB with PC software
Power	100 to 240 VAC (0.4 A RMS at 230 VAC) or 24 VDC plus or minus 10% (1.04 A)
Display and enclosure	2 x 16 backlit LCD, 6-button keypad; NEMA 4X (IP66) hazardous-area enclosure; remote-probe version with junction box (E4)
Approvals as printed	cFMus: Class I Div 1 Groups B, C, D T3C, Type 4X; ATEX and IECEx: II 2 G Ex db IIC T3 Gb, II 2 D Ex tb IIIC T200 degrees C Db; Ta -20 to 60 degrees C for ATEX/IECEx
Straight run (in-line with conditioner)	Upstream 1D after a single 90 degree elbow, 3D after two elbows, 5D after a control valve; 0D downstream
Leak integrity	5 x 10-9 sccs helium maximum

Ordering the 780i

The order code is built from the parent (780i-VT or 780i-VTP), flow body (for example N200 for a 2 inch NPT male body or F400 for a 4 inch ANSI 150 flange), electronics enclosure (E2 on-probe or E4 remote), input power (P2 24 VDC or P3 100-240 VAC), display, communications (XX, MB or BH), approvals (NA, UC or EX) and calibrations. Air is always included; three further gases can be selected from the qTherm library or ordered as actual-gas calibrations, with other gases and mixtures by consultation. Options include a non-resettable totalizer, qMix gas-mixing licence, remote cables of 10 to 100 feet and oxygen cleaning for meters up to 4 inches (DN100).

Applications and what to confirm

Typical duties are natural gas, flare gas, biogas, compressed air, nitrogen and process gas lines where a low pressure drop is needed. Sierra states the meter keeps accuracy when gas composition changes if the qMix app is matched to a gas chromatograph. Confirm the gas, pressure, line size, approval, communications and calibration range before ordering, and note that steady straight-run rules apply. For the insertion version see the Sierra QuadraTherm 640i; more instruments are under Flowmeters. The attached 640i/780i datasheet holds the dimensions, gas tables and ordering codes.

Datasheets & Documents

Datasheet Sierra QuadraTherm 640i/780i datasheet Download

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About brand

Thermal gas mass flow measurement is the core of Sierra Instruments, a manufacturer founded in 1973 and based in Monterey, USA. Its meters read mass flow directly, without separate pressure and temperature compensation, which is why they turn up on compressed air, natural gas, flare and aeration lines. Seven Star LLC sources and supplies Sierra thermal mass flow meters and controllers for plants in Oman, including the QuadraTherm, SmartTrak and FastFlo models listed on this page.

Sierra product families listed here

The QuadraTherm 640i is an insertion thermal mass flow meter for air and gas in larger pipes and ducts. Its inline counterpart, the 780i, has built-in flow conditioning. SmartTrak 100 is a digital mass flow meter and controller for multiple gases, used on lower flows in laboratories, skids and gas blending. FastFlo 620S is a fast-response insertion sensor for air flow in pipes. Sierra also builds InnovaMass vortex meters for steam, gas and liquid.

Ordering Sierra flow meters: what we need

Send the full model code from the nameplate, or the serial number. For a new meter we need the gas or gas mixture, flow range, line pressure and temperature, pipe size and schedule, process connection, supply voltage, output signal and any hazardous-area approval the site requires. Projects in the GCC often ask for the factory calibration certificate, so say so in the inquiry.

Browse Sierra Instruments products by category: Flowmeters.