ST80/ST80L Mass Flow Meters

Mass Flow Meters with Adaptive Sensing Technology

Ready for Whatever Comes Down The Pipe!

ST80 is a high performance, rugged thermal dispersion technology air/gas flow meter that combines ultra-reliable, feature-rich electronics, and FCI innovations such as Adaptive Sensing Technology™ (AST™) with the industry's most extensive selection of application-matched flow sensors, including FCI's patented "FPC" sensor for compressed air and new "wet gas" flow element, to provide a truly superior solution for industrial processes and plant applications. The ST80 further combines these features with a robust, rugged transmitter enclosure and industry’s broadest selection of process connections to provide longest service life and ease-of-installation in your installation’s pipe or duct.

The ST80 Series transmitter’s outputs are a match to your DCS, PLC, SCADA, recorder, or alarm system.  Whether your output needs are traditional 4-20 mA analog or advanced digital bus communications such as HART, Foundation Fieldbus, PROFIBUS PA, PROFIBUS DP, or Modbus, ST80 has you covered.  Then for local display, the ST80’s graphical, backlit LCD is unmatched in showing what’s happening in the pipe.  Flow rate, totalized flow, and temperature are continuously displayed in both a digital and bar graph presentation, while alarms and/or diagnostic messages will display as needed to alert operators.

  • Direct mass flow measuring
  • Flow rate, totalized flow, temperature
  • No moving parts, virtually no maintenance
  • Patented AST™ thermal measuring mode
  • Process temperatures up to 850°F [454°C]
  • Analog outputs and bus communications
  • Global agency approvals for hazardous Ex installations
  • SIL 1 compliant
  • Graphical multivariable LCD readout
  • 3-point in-situ calibration drift check
  • Exclusive wet gas/rain shield sensor option
  • Integral or remote mounting
  • Aluminum or stainless steel enclosures


  • Measuring Capability: Flow rate, total flow and temperature 
  • Basic Styles
ST80: Insertion, single-point  (for pipe diameters > 2 inches [51 mm])
ST80L: In-line (spool piece), single-point  (for pipe diameters 1 inch to 2 inches [25 mm to 51 mm])
  • Flow Measurement Range
Insertion Style: 0.25 SFPS to 1000 SFPS [0,07 NMPS to 305 NMPS]
ST80L In-line: 0.0062 SCFM to 838 SCFM [0,01 Nm3/h to 1425 Nm3/h]
Air at standard conditions; 70°F psia and 14.7 psia [0°C and 1,01325 bar (a)]
  • Temperature Measurement Range
Up to 850°F [454°C] commensurate with element; see Operating Temperature in Flow Element specification
  • Media: all gases that are compatible with the flow element materials
  • Accuracy:
Flow: ± 1.0% reading, ± 0.5% full scale
Temperature: ±2 °F [± 1.1°C] (display only, flow rate must be greater than 5 AFPS [1,5 m/sec])
  • Temperature Coefficient
With optional temperature compensation; valid from 10% to 100% of full scale calibration
Flow: Maximum ± 0.015% of reading / °F up to 850°F [± 0.03% of reading / °C up to 454°C]
  • Repeatability
Flow: ± 0.5% reading
Temperature: ±1 °F [±1°C] (flow rate must be greater than 5 AFPS [1,5 NMPS])
  • Response Time (Flow):  1 sec. to 63% of final value (1 step change) typical with -FP or -FPC type flow element operating in AST™ mode
  • Turndown Ratio
Normally factory set and field adjustable from 2:1 to 100:1 within calibrated flow range.
  • Temperature Compensation
Standard: ± 30°F [± 16°C]
Optional: ± 100°F [± 55°C]
  • Calibration: Performed on flow stands using equipment traceable to NIST and ISO/IEC 17025
  • Agency Approvals:
FM/FMc: Class I, Division 1, Explosion proof, Groups B,C,D
Class II/III, Division 1, Dust ignition proof, Groups E,F,G
Class I, Division 2, Nonincendive, Groups A,B,C,D
Class II, Division 2, Nonincendive, Groups E,F,G
Class III, Division 1,2, Dust ignition proof, indoor/outdoor Hazardous (Classified) locations
Type 4x/IP67 (per NEC 500)
ATEX: II 2 G Ex db IIC T6...T1 Gb Ta= -40°C TO 65°C, IP66/67
II 2 D Ex tb IIIC T85°C...T450°C Db Ta= -40°C TO 60°C, IP66/67*
IECEx: Ex db IIC T6...T1 Gb Ta= -40°C TO 65°C, IP66/67
Ex tb IIIC T85°C...T450°C Db Ta= -40°C TO 60°C, IP66/67*
Pressure Directive 032/2013 (Model ST80L)
Complies with Canadian Electrical code requirements of ANSI / ISA 12.27.01-2011 as a single seal device
* Available in standard and elevated T-ratings
* T-Rating (Probes)  Process Temperature Range
          Standard Optional Elevated**
T4/T135°C    -40°C to +65°C    -40°C to +89°C
T3/T200°C    -40°C to +115°C    -40°C to +154°C
T2/T300°C    -40°C to +177°C    -40°C to +254°C
T1/T450°C    -40°C to +365°C    -40°C to +404°C
** With elevated T-rating, instruments will be fixed in AST measuring mode, not field changeable into CP mode.
  • SIL/IEC 61508: SIL 1 compliant, SFF 71.1% to 79.1%
  • Other: Follows best practices and guidelines as set forth in ISO 14511; Complies with ISO 14164

Flow Element

  • Material of Construction
All-welded 316L stainless steel; optional Hastelloy-C276
  • Operating Pressure
Model ST80 (Insertion style)
Metal ferrule: 1000 psig [70 bar (g)]
Teflon ferrule: 150 psig [10 bar (g)] (200°F [93°C] maximum)
Fixed Connection NPT: 1000 psig [70 bar (g)]
Fixed Connection Flanged: per flange rating
Model ST80L (inline style)1000 psig [70 bar (g)]
  • Operating Temperature (Process)
Model ST80 (Insertion style)
Flow Elements (– FPC, – FP and – S):
-40°F to 350°F [-40°C to 177°C]
-40°F to 500°F [-40°C to 260°C]
-40°F to 850°F [-40°C to 454°C]
Wet gas/rain flow element: -40°F to 350°F [-40°C to 177°C]

Model ST80L (In-line Style): -40°F to 257°F [-40°C to 125°C]

Process Connections:
Compression Fittings Model ST80
3/4" or 1" MNPT, stainless steel with adjustable Teflon ferrule or metal ferrule; or flanged tapped and threaded for 3/4" fitting, ANSI or DIN flanges.
Compression fittings not available with 850°F [454°C] temperature versions.
Retractable Packing Glands
Low pressure 50 psig [3,5 bar (g)] or medium pressure 500 psig [34 bar (g)] with graphite or Teflon packing material; 1 1/4" MNPT or ANSI or DIN flange
Teflon packing required when process media is ozone, chlorine or bromine.
Remote configuration required with medium pressure packing gland.

Fixed Fittings / All Welded
1" male NPT or ANSI or DIN flange
Insertion Length:
Field adjustable lengths: (probe is etched with depth ruler in both inches and mm)
1" to 6" [25 mm to 152 mm]
1" to 12" [25 mm to 305 mm]
1" to 21" [25 mm to 533 mm]
1" to 36" [25 mm to 914 mm]
1" to 60" [25 mm to 1524 mm]
Fixed lengths: from 2.6" to 60" [66 mm to 1524 mm]
  • Model ST80L In-line Flow Tube
Flow element is threaded and keyed in an in-line flow tube, calibrated and supplied as a spool-piece; options include low flow injection tubes and built-in Vortab flow conditioners for optimum low flow rangeability and performance
Size: 1" diameter tubing; 1", 1 1/2" or 2" schedule 40 pipe; 1" schedule 80 pipe
Length: 9 nominal diameters
Process Connections: Female NPT, MNPT, ANSI or DIN flanges, or butt weld prepared
Option: Flanges sized for flow tube
  • Remote Transmitter Configurations:
Transmitter may be mounted remotely from flow element using interconnecting cable (up to 1000' [300 m])
Flow Transmitter
  • Operating Temperature
-40°F to 150°F [-40°C to 65°C]
  • Input Power:
AC: 85 Vac to 265 Vac, 50 Hz to 60 Hz; 10 watt maximum
DC: 24 Vdc ± 20%; 9 watt maximum
  • Outputs (Standard, Included)
Analog: Two (2) 4-20 mA* user assignable to flow rate or temperature. Outputs are user programmable to full flow range or subsets of full flow range.
* Outputs are isolated and have fault indication per NAMUR NE43 guidelines, user selectable for high (>21.0 mA) or low (<3.6 mA) 
  StandardHART (v7 compliant), Modbus RS-485 and USB Serial I/O.
  Optional: (Can be added to above) Foundation Fieldbus H1, PROFIBUS-PA, or PROFIBUS-DP
 (Note: Only one bus comm, HART, Modbus, Fieldbus or PROFIBUS can be active at same time)
  • Enclosures:
Main Transmitter / Electronics:
NEMA 4X, IP66/67; polyester powder coated, ≤0.4% CU, low/no copper content* aluminum or optional in stainless steel; 4 conduit ports threaded as 1/2" NPT or M20x1.5; 7.74" x 5.40 " x 5.00" [196,6 mm x 137,2 mm x 127 mm].  (*standard effective April 2023)
Local Enclosure (Remote Configuration):
Model ST80 without packing gland option and Model ST80L
  NEMA 4X, IP67; polyester powder coated aluminum or stainless steel; 2 conduit ports threaded as 1/2" NPT or M20x1.5; 3.75" x 4.00" x 3.24" [95 mm x 102 mm x 82 mm]
Models ST80 with packing gland option:
  NEMA 4X, IP67; polyester powder coated aluminum or stainless steel; 1 conduit port threaded as 1" NPT or M20x1.5; 5.40" x 4.82" [137.2 mm x 122 mm]
  • Readout/Display (Optional):
    • Large 2" x 2" [50 mm x 50 mm] LCD; digital plus bar graph and engineering units
    • Digital displays of flow rate, total flow, temperature and pressure (with STP models); user selectable for engineering units
    • Analog bar graph of flow rate
    • Alarm status indication
    • User programmable 20 alphanumeric character field associated with each calibration group
    • Set-Up & Service mode displays text and service codes
    • Backlighted
    • Display is electronically rotatable in 90° increments to optimize viewing angle
  • Touch Button/Keypad (Optional)
    • Four (4) optical touch buttons
    • For user programming of instrument set-up and service interrogation
    • Activation through front window – no need to open enclosure to access or activate
    • Set and adjust the meter or interrogate diagnostics in-situ, even in Hazardous Ex (Div.1/Zone1) installation.
Note: If readout/display with buttons not ordered, all user set-up and service diagnostics interrogation must be done via computer link to bus comm and/or USB port.


  • Vortab Flow Conditioners

Available for all line size applications; standard choice with Model ST80L (in-line)
  • Sun Shield, FCI part number 022378-01

Shades main transmitter electronics and display from direct sunlight. 316LSS
  • Ball Valves / Cable Glands
  • Element Coatings and Materials

For service in highly corrosive gases or with erosive particulates, FCI can provide special coatings and wetted materials to protect the element and provide longer service life; examples include Kynar, Tantalum, and chromium carbide
  • Certification and Testing Documentation

NACE, CMTR's, CRN registration (pending), oxygen cleaning, welding qualifications, NIST certs, pressure testing, dye penetrant, and more available.

Specifications at reference operating conditions of 70°F, 14.7 psia [21.1°C, 1,013 bar (a)] and straight pipe run 20d upstream, 10d downstream FCI is a continuous improvement company; specifications subject to change without notice


ATEX CEFMcFDTFoundation FieldbusHARTEACIEC/IECExNepsiProfibusModbus
  • ATEX
  • CE
  • CPA
  • CRN
  • FMc
  • FM
  • Foundation Fieldbus
  • HART
  • IECEx
  • SIL (IEC 61508)
  • UKCA
  • UKEX