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ST98 Mass Flow Meter for Air and Gases

Mass Flow Meter ST98

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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.


Direct Mass Flow Measuring No Moving Parts
Flow, Total Flow, and Temperature No Scheduled Maintenance
Gas Temperatures to 850ºF [454ºC] All Welded Wetted Parts
Integral and Remote Electronics Versions Rugged, All Metal Enclosures
Extensive Global Agency Approvals HART Option


  • 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]
  • Repeatability:
    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.

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.
  • Outputs:
    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.

Other Options and Accessories

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

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