ST98L Mass Flow Meter

Mass Flow Meter Summary

The ST98L in-line style mass flow meter is the flow measurement solution for virtually any gas or gas mixture in line sizes 1 inches to 2 inches [25 mm to 50 mm]1. With ST98L, FCI combines superior, equal mass thermal-dispersion flow sensing elements and precision electronics with exacting actual fluid calibration and a choice of rugged, industrial enclosures to deliver accurate, highly repeatable flow measurement and long lasting service for the most demanding processes.

Note 1: For line sizes larger than 2 inches [50 mm], see Model ST98 insertion style


  • Direct mass flow measuring
  • Flow, total flow, and temperature
  • Gas temperatures to 350ºF [177ºC]
  • Integral and remote electronics versions
  • Extensive global agency approvals
  • No moving parts
  • No scheduled maintenance
  • All welded wetted parts
  • Rugged, all metal enclosures
  • HART and PROFIBUS comm options


Flow Range: 0.75 SFPS to 600 SFPS [0,21 to 172 NMPS] 
(Air at standard conditions of 70º F and 14.7 psia [0ºC and 1013,25 mBar(a)].)

Accuracy: (at calibrated conditions)
  • Flow: ± 1% reading + 0.5% full scale
  • Temperature: ± 1ºF [± 0,6ºC]
  • Temperature Coefficient:
With optional temperature compensation; valid from 10% to 100% of full-scale calibration 
Flow: Maximum ± 0.015% of reading/ºF up to 850ºF [±0.03% of reading/ºC up to 454ºC]

  • Flow: ± 0.5% reading
  • Temperature: ± 1º F [± 0,6º C]

Turndown Ratio: Factory set and field adjustable from 10:1 to 100:1 within the calibrated flow range

Temperature Compensation: 
  • Standard: ± 30ºF [± -1ºC]
  • Optional: ± 100ºF [± 38ºC]

Agency Approvals: FM, ATEX, IEC, CSA, CRN, GOST/RTN, NEPSI, CPA, PED, CE Marking (system approvals)

Calibration: NIST certified and traceable test lab calibration

MTBF (calculated): 110 years

Flow Element

Materials of Construction: All welded 316L stainless steel or Hastelloy-C for all wetted surfaces

Process Connection: Female NPT on 1" tubing; Male NPT on 1", 1.5" or 2" schedule 40 pipe. Optional: ANSI or DIN flanges

Inline Flow Tube Diameter / Length (from inlet to outlet):
  • 1" tubing / 9" [229 mm]
  • 1" schedule 40 pipe / 9" [229 mm] 
  • 1.5" schedule 40 pipe / 13.5" [343 mm]
  • 2" schedule 40 pipe / 18" [457 mm]
  • Customer specified fixed lengths are available; consult FCI

Operating Temperature (Process):
  • Standard: -40ºF to 350ºF [-40ºC to 177ºC]
  • Operating Pressure: To 250 psig [17 bar(g)]

  • Low flow injection tubes
  • Built-in Vortab® flow conditioners

Flow Transmitter

Operating Temperature: 0ºF to 140ºF [-18ºC to 60ºC]

Input Power (Field Selectable): 85 Vac to 265 Vac, 22 Vdc to 30 Vdc; 7 watts max; 230mA max.

Analog output: 4-20 mA, 1-5 Vdc, 0-5 Vdc, or 0-10 Vdc; user selectable
(mA: 700 ohm max. load; output per NAMUR guideline NE 431, field selectable for high ±21.6mA or low ±3.75mA.)
(Isolated from input power in AC powered mode only.) 
(Vdc 100K min. load.) 

Digital Communications: RS-232C Serial I/O standard.

Options: HART, full two-way; PROFIBUS, DP, profile 3, certification #Z01212

Digital Display: Optional LCD, 2 lines by 16 characters per line. Indicates flow rate and process temperature or totalized flow (field selectable) with engineering units displayed

Remote Configuration: Transmitter may be mounted up to 1000' [350 m] from flow element

Enclosure Options:
  • NEMA 4/IP66 rated carbon steel box, approved for installation in Nonincendive Class I, Div.2, Groups A,B,C,D and suitable for Class II, Div.2 Groups F, G; Class III, Div. 2
  • NEMA 4X/IP66 rated aluminum box, approved for installation in Nonincendive Class I, Div.2, Groups A,B,C,D and suitable for Class II, Div.2 Groups F, G; Class III, Div. 2
  • Hazardous location, Ex-type aluminum, approved for installation in Class I, Div.1, Groups B,C,D,E,F,G; ATEX II2, GD, Exd IIC, T4


Model FC88: Field Programmer/Communicator. Hand-held plug-in interface used to perform instrument set-up, programming, and for trouble-shooting.

VORTAB® Flow Conditioners: For use in piping installations with inadequate straight run, inline or out-of-plane elbows, control valves or any other obstructing configurations to improve flow meter performance.


  • ATEX
  • CCoE
  • CE
  • CPA
  • CRN
  • CSA
  • FM
  • IECEx
  • IECEx Test Report
  • HART