Series-ST80

Supported Applications

The FCI ST80 Series is a thermal dispersion mass flow meter designed for direct air and gas measurement, providing flow rate, totalized flow, and temperature outputs. The series serves applications in line sizes from 1" to 100" [25 mm to 2500 mm] and larger. Documented compatible media include all gases that are compatible with the flow element material, specifically listing air, compressed air, natural gas, hydrogen, nitrogen, oxygen, carbon dioxide, methane, propane, ethylene, ammonia, acetylene, chlorine, sulfur dioxide, landfill gas, digester gas, various Freon refrigerants (R-12 through R-504), silane, styrene, toluene, vinyl acetate, and uranium hexafluoride. The series supports specific sensor configurations for clean gases, slightly dirty gases, damp/moist gases, very dirty gases, wet gases with entrained moisture or rain-shielded vertical stacks, erosive/corrosive media, particulates in the flow stream, pulsing flows, dynamic temperature swings, and rapid/erratic flow changes.

Operating Conditions & Performance

The ST80 Series operates with a measurement range of 0.25 SFPS to 1000 SFPS [0.07 NMPS to 305 NMPS] for the insertion style (ST80) and 0.0062 SCFM to 1850 SCFM [0.01 NMCH to 3,140 NMCH] for the in-line style (ST80L), based on air at standard conditions of 70 °F and 14.7 psia [21 °C and 1,01325 bar (a)]. Temperature measurement extends up to 850 °F [454 °C] commensurate with the element selection. Accuracy for gas-specific calibration is ±1.0% reading, ±0.5% full scale; temperature accuracy is ±2 °F [±1,1 °C] (display only) when flow rate exceeds 5 SFPS [1,5 m/sec]. Repeatability is ±0.5% of reading for flow and ±1 °F [±0.6 °C] for temperature under the same minimum flow condition.

Process operating temperatures vary by connection type: compression fittings support Lo (350 °F [177 °C]) to Med (500 °F [260 °C]); low-pressure packing glands support Lo/Med; medium-pressure packing glands and fixed NPT/flange connections with remote transmitters support Hi service up to 850 °F [454 °C]. Ambient operating temperature for the flow transmitter/electronics is -40 °F to 140 °F [-40 °C to 60 °C], with a storage range of -76 to 150 °F [-60 to 65 °C]. The enclosure rating is Type 4X, IP66/IP67. Response time for flow is typically 1 second to 63% of final value (one step change) with -FP or -FPC type elements operating in AST mode.

Configuration Options

The series offers extensive configuration options across two basic styles: ST80 Insertion and ST80L In-line. Key configurable dimensions include:

• Sensor Elements & Materials: Flow elements are available in -FPC, -FP, -S (retractable), and -WG (Wet Gas MASSter) styles. Wetted materials include all-welded 316L stainless steel or optional Hastelloy-C276.
• Process Connections: ST80 insertion models support compression fittings (3/4" or 1" male NPT with Teflon or metal ferrules), retractable packing glands (low pressure ≤50 psig [3.5 bar(g)] or medium pressure ≤500 psig [34 bar(g)]), and fixed connections (1" male NPT, ANSI/DIN flanges). ST80L in-line models support female/male NPT, ANSI/DIN flanges, or butt weld preparations for 1", 1-1/2", and 2" pipe/tubing.
• Insertion Lengths: Field-adjustable lengths range from 1" to 60" [25 mm to 1524 mm] in increments of 6, 12, 21, 36, and 60 inches. Fixed lengths are available from 2.6" to 60".
• Outputs & Communications: Standard outputs include two isolated 4-20 mA analog channels (user assignable) with HART V7 compliance and Modbus RS-485. Optional digital protocols include FOUNDATION Fieldbus H1, PROFIBUS PA, and PROFIBUS DP.
• Housing & Mounting: Transmitters are available in integral or remote configurations (up to 1000 ft [300 m] cable). Enclosures are polyester powder-coated aluminum or optional 316L stainless steel. Display options include a backlit LCD with optical touch buttons for field programming.
• Approvals: The series holds FM/FMc (Class I Div 1/2, Class II/III), ATEX/UKEX (II 2 G Ex db IIC T6...T1 Gb; II 2 D Ex tb IIIC T85°C...T450°C Db), and IECEx certifications. It is SIL 1 Compliant per IEC 61508.

Key Product Differences

The ST80 Series distinguishes between the insertion style (ST80) for large pipe diameters and the in-line spool piece style (ST80L). The ST80 supports variable insertion lengths to accommodate pipes from 1" up to 100", whereas the ST80L is a fixed-body meter available in 1" tubing, or 1", 1-1/2", and 2" Schedule 40/80 pipe sizes. Sensor selection varies by application: -FPC style elements are optimized for clean gases with fast response; -FP style suits slightly dirty gases; -S style is designed for damp/moist, very dirty, or erosive/corrosive media; and the -WG (Wet Gas) element handles entrained moisture or rain-shielded vertical stacks. Temperature service limits differ by connection: compression fittings are not available with 850 °F [454 °C] versions, which require retractable packing glands or fixed flanged connections.