ST98 Mass Flow Meter

Mass Flow Meter Summary

The ST98 insertion-style mass flow meter is the flow measurement solution for virtually any gas or gas mixture in line sizes from >2 inches up to 42 inches [50mm to 1066mm].1 With ST98, 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 2 inches [50mm] and smaller, see Model ST98L in-line style.


  • No Moving Parts
  • No Scheduled Maintenance
  • All Welded Wetted Parts
  • Rugged, All Metal Enclosures
  • HART Option
  • Direct Mass Flow Measuring
  • Flow, Total Flow, and Temperature
  • Gas Temperatures to 350ºF [177ºC]
  • Integral and Remote Electronics Versions
  • Extensive Global Agency Approvals


Flow Range: 0.75 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: ± 2º F [± 1º C]
  • 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 454 ºC]

  • 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: ± 30º F [± -1º C]
  • Optional: ± 100º F [± 38º C]

Agency Approvals: FM, ATEX, IEC, CSA, CRN, GOST/RTN, NEPSI, CPA, PED, CE Mark (system approvals)
Complies with Canadian Electrical code requirements of ANSI / ISA 12.27.01-2011 as a single seal device.

Calibration: N.I.S.T. 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:
  • Standard: 0.75 or 1 inch male NPT stainless steel compression fitting with adjustable Teflon ferrule rated up to 150 psig [10 bar (g)] and 200ºF [93ºC], or metal ferrule rated up to 250 psig [17 bar (g)] and 350ºF [177ºC].

Optional: Thread-on ANSI or DIN flanges, or retractable sensing element.

Insertion Lengths (Field Adjustable):2
  • 1 to 6 inches [25 to 152 mm]
  • 1 to 12 inches [25 to 305 mm]
  • 1 to 21 inches [25 to 533 mm]
  • Customer specified fixed lengths are available. Consult FCI.

Operating Temperature (Process):
  • Standard: -40º to +350º F [-40º to +177º C]
  • Optional high temp: -100º to +500º F [-73º to +260º C]; 
  • Optional ultra-high temp: -100º to +850º F [-73º to +454º C];

Operating Pressure: To 250 psig [17 bar(g)]; de-rated with Teflon ferrule.

Note 2: After installation, stainless steel ferrule will be permanently fixed at the installed length.

Flow Transmitter

Operating Temperature: 0º to 140º F [-18º to +60º C]

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

  • Analog output: 4 to 20 mA, 1-5Vdc, 0-5Vdc, or 0-10Vdc. 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

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 ft. [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
  • BelGIM (Products)
  • BelGIM (Pattern)
  • CCoE
  • CE
  • CPA
  • CRN
  • CSA
  • FM
  • EAC/TR CU (Russia)
  • IECEx
  • IECEx Test Report
  • HART