ST100A Mass Gas Flow Meters

Advanced Mass Flow Meters for Industrial Processes and Plant Applications

The Science of Process Gas Flow Metering Advanced, Future Ready!

ST100A is high performance thermal dispersion technology gas flow meter that combines the most feature- and function- rich electronics, and innovations such as FCI patented Adaptive Sensing Technology™ (AST™), with the industry's most advanced flow sensors such as FCI patented "FPC" flow element for compressed air flow and new "wet gas" sensor to achieve a truly state-of-the-science flow metering solution for industrial processes and plant applications. 

The ST100A series transmitter is unsurpassed in meeting your current and future need for outputs, process information and communications. Whether your output needs are traditional 4-20 mA analog, frequency/pulse, or advanced digital bus communications such as HART, Foundation fieldbus, PROFIBUS, or Modbus, ST100A has you covered. ST100A's bus communications have been certified by and are registered devices with HART and Foundation Fieldbus. In addition, Emerson Process (Delta V)Yokogawa and ABB (800xA) (see page 6) have tested and verified ST100A Series' Foundation Fieldbus interoperability with their systems.  

Then there's ST100A's display/readout, which brings new meaning to the term process information. Simply, the ST100A's graphical display provides the most comprehensive information on the process measurements and conditions of any thermal flow meter available - see the ST100A close-up page for all the details. 

To complete the solution, ST100A flow elements and process connections ensure the best possible measurements and effective installation. FCI flow element designs have been perfected and optimized through six decades of R&D and real world experience in thermal dispersion technology and flow metering applications. With thermal dispersion there are no moving parts to foul or clog. This results in the greatest reliability and valuable savings on maintenance. 

Fast response, accuracy, repeatability and long-life are hallmarks of FCI flow elements available with ST100A. And, all new are the STP models, which add pressure measurement. Mass flow, temperature and pressure in a single tap-point thermal dispersion meter… An industry first and FCI exclusive! Then, consider other ST100A Series exclusives like dual-element measuring systems and FCI’s patented VeriCal option that provides significant cost and time savings by performing dynamic calibration verification in-situ, without ever removing the instrument from the process. To ensure both ease of installation and a match with your process conditions, ST100A offers a comprehensive selection of process connections and installation options.

Watch the ST100 Series Demo with close-ups of all models and their features (Flash Player Required)


  • Measuring Capability
ST1XXA Models: Flow rate, total flow and temperature 
STP1XXA Models: Flow rate, total flow, temperature and pressure
  • Basic Styles
ST100A: Insertion, single-point
ST100AL: In-line (spool piece), single-point
ST102AA: Insertion, dual-element averaging system
ST110A: Insertion, single-point with VeriCal™ capability
ST112AA: Insertion, dual-element averaging system with VeriCal™ capability
STP100A: Insertion, single-point with pressure measurement
STP110A: Insertion, single-point with pressure measurement and VeriCal™ capability
  • Flow Measurement Range
Insertion Style: 0.25 SFPS to 1000 SFPS [0,07 NMPS to 305 NMPS]
ST100AL 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
  • Pressure Measurement Range (STP Models)
Available Ranges:
0 psig to 50 psig [0 bar (g) to 3,4 bar (g)]
0 psig to 160 psig [0 bar (g) to 11 bar (g)]
0 psig to 500 psig [0 bar (g) to 34 bar (g)
0 psig to 1000 psig 0 bar (g) to 70 bar (g)]
  • Media: all gases that are compatible with the flow element materials
  • Accuracy:
Flow: ± 0.75% 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])
Pressure (STP Models): ± 1.0% of span
  • 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])
Pressure (STP Models): ≤ 0.1% of span
  • Response Time (Flow):  1 sec. to 63% of final value (1 step change) typical with -FP or -FPC type flow element and AST electronics.
  • Turndown Ratio
Normally factory set and field adjustable from 2:1 to 100:1 within calibrated flow range; up to 1000:1 possible with factory evaluation of application
  • 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: EX d IIC Gb T6/T1 Ta= -40°C TO 65°C
Ex tb IIIC T85°C/T450°C Db Ta= -40°C TO 65°C, IP67
II 2 G Ex d IIC Gb T6/T1 Ta= -40°C TO 65°C, IP67
Other: NEPSI, EAC/TR CU, Kazakh MPA (Kazakhstan), CRN, Inmetro, CPA, EQM/ECAS, UKCA(UKEX) CE Marking
Complies with Canadian Electrical code requirements of ANSI / ISA 12.27.01-2011 as a single seal device.
Ex-rated pressure transducer STP models:
FM/CSA: Class 1, Division 1, Groups A,B,C,D
Dust ignition proof for Class 1, Division 1, Groups E,F,G
ATEX: 2 G Ex d C T4, Ex d IIC T5, Ex d IIC T6

Flow Element

  • Material of Construction
All-welded 316L stainless steel; optional Hastelloy-C276
  • Operating Pressure
  Insertion Types
  ST Models
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
  STP Models: per above or pressure sensor rating, whichever is less 
  Inline Type (Model ST100AL): 1000 psig [70 bar (g)]
  • Operating Temperature (Process)
ST100A, ST102AA Insertion Style
All 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]
ST110A, ST112AA Insertion Style
– FP Style Flow Element:
-40°F to 350°F [-40°C to 177°C]
-40°F to 500°F [-40°C to 260°C]
STP Series Insertion Style
– FP Style Flow Element:
Standard Pressure Sensor: -32°F to 176°F [0°C to 80°C]
Ex-rated Pressure Sensor: -22°F to 212°F [-30°C to 100°C]
ST100AL In-line Style
– FP and – S Style Flow Element:
-40°F to 250°F [-40°C to 121°C]
  • Process Connection:
Compression Fittings Models ST100A and ST102AA only
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 of ST100A or ST102AA
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:
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]
  • ST100AL 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
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])
  • Additional Specifications on Pressure Sensor
Standard Sensor PSI Bar PSI Bar PSI Bar PSI Bar
Pressure range 50 3,4 160 11 500 34 1000 70
Over Pressure Safety 100 7 290 20 1000 70 1740 120
Burst Pressure 250 17,24 500 34 2500 172 7975 550
Wetted Materials        
Connection 316L 316L 316L 316L
Pressure Sensor PH 13-8 SS 316L 316L 316L
Ex-rated Sensor PSI Bar PSI Bar PSI Bar PSI Bar
Pressure range 50 3,4 160 11 500 34 1000 70
Over Pressure Safety 240 16,55 1160 80 1160 80 1740 120
Burst Pressure 290 20 1390 95,84 5800 400 7970 549,5
Wetted Materials        
Connection Stainless Steel Stainless Steel Stainless Steel Stainless Steel
Pressure Sensor Stainless Steel Stainless Steel SS and Elgiloy SS and Elgiloy

Flow Transmitter

  • Operating Temperature
-40°F to 150°F [-40°C to 65°C] (all except dual element models)
Dual-element Models: -40°F to 120°F [-40°C to 49°C]
  • Input Power:
AC: 85 Vac to 265 Vac, 50 Hz to 60 Hz; single element; 10 watt; dual element: 13.1 watt maximum
DC: 24 Vdc ± 20%; single element; 9 watt; dual element: 13.2 watt maximum
  • Outputs
Standard: Three (3) 4-20 mA*, 0-1kHz, or 0-10 kHz pulse/frequency 4-20 mA outputs are user assignable to flow rate, temperature and/or if so equipped, pressure; outputs are user programmable to full flow range or subsets of full flow range; pulse/frequency output is user selectable as pulse for external counter/flow totalizer, or as 0-1 kHz or 0-10 kHz frequency representing flow rate
* Outputs are isolated and have fault indication per NAMUR NE43 guidelines, user selectable for high (>21.0 mA) or low (<3.6 mA) 
Standard: HART (v7 compliant), Modbus 485,  USB, Ethernet (as service port)
Optional: Foundation fieldbus H1 or PROFIBUS PA
(* ST100A Series are certified by and registred with FieldComm Group (HART and Foundation fieldbus organizations)
  • Auxiliary Inputs: Two 4-20 mA input channels; used for FCI administered special configurations to allow ST100A Series to accept inputs from external devices such as gas analyzers, gas composition or pressure sensors
  • Enclosures:
Main Transmitter / Electronics:
NEMA 4X, IP67; polyester powder coated, ≤0.4% CU, low/no copper content*2 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 ST100AL, Models ST100A and ST102AA without packing gland option:
  NEMA 4X, IP67; polyester powder coated, ≤0.4% CU, low/no copper content*2 aluminum; 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 ST100A and ST102AA with packing gland option; ST110A, ST112AA and                      all STP Models:
  NEMA 4X, IP67; polyester powder coated, ≤0.4% CU, low/no copper content*2 aluminum; 1 conduit port threaded as 1" NPT or M20x1.5; 5.40" x 4.82" [137.2 mm x 122 mm]

All models with stainless steel enclosure option:
NEMA 4X, IP67; stainless steel; 1 conduit port threaded as 1" NPT or M20x1.5; 5.40" x 4.82" [137.2 mm x 122 mm]
(*2:  Standard effective April 2023)
  • Data Logger: User programmable for readings per time increment to a maximum of 1 reading/second; removable, circuit board-mountable 8GB micro-SD (secure digital) memory card supplied; stores approximately 80M readings in ASCII comma-separated format
  • Readout/Display and Optical Touch Buttons (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
    • Four (4) optical touch buttons for user programming of instrument set-up and service interrogation
    • Optical touch button activation through front window – no need to open enclosure to access or activate
    • Display is electronically rotatable in 90° increments to optimize viewing angle
Note: If readout/display 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 ST100AL (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, 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


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DCS Compatibility Verification