Fluid Components Intl ST51A, Installation, Operation & Maintenance Instruction Manual

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ST51A/ST75A/ST75AV Mass Flow Meters GENERAL
Fluid Components International LLC 1
1 GENERAL
Product Description
The ST51A and ST75A/ST75AV Series are thermal dispersion, industrial process grade air/gas flow meters. They are suitable for all air
and gas flow measurement applications. The ST51A is an insertion type flow meter for line sizes ranging from 2″ to 24″ [51 to 610 mm].
The ST75A is an in- line type flow meter for line sizes ranging from ¼″ to 2″ [6 mm to 51 mm] . Both ST51A and ST75A/ST75AV flow meters
provide direct mass flow measuring and measures flow rate, totalized flow and temperature.
The measurements are made available to the user through dual 4-20 mA analog output channels, a separate source and sink channel (pulse
output for totalizer or level output for alarm) and HART. The optional alphanumeric LCD display provides real-time process variable values, flow
range and process description information. There are no moving parts to clean or maintain. These flow meters are offered in a wide selection of
process connections to fit with any process piping and versions are available for temperature service from -0 °F [-18 °C] to 350 °F [177 °C].
ST51A and ST75A/ST75AV’s electronics/transmitter can be integrally mounted with the flow sensor or remote mounted up to 100
′ [30 m]
from the sensor element. All ST51A and ST75A/ST75AV flow meters are precision calibrated in FCI’s world-class, NIST traceable
calibration facility on one of our flow stands matched to the customer’s gas application and actual installation conditions.
Theory of Operation
The instrument is functionally based on the thermal dispersion operating principal. A low powered heater produces a temperature
differential (ΔT) between two Resistance Temperature Detectors (RTDs) by heating one of the RTDs above process temperature. As the
process mass flow rate increases, the temperature d ifferential (ΔT) between the RTDs decreases. The ΔT between the RTDs is
proportional to the process mass flow. The flow transmitter converts the RTD’s ΔT signal into a scaled flow output signal. The signal from
the unheated RTD is used to provide the process temperature value.
Safety Instructions
Warning: Explosion Hazard. Do not disconnect equipment when flammable or combustible atmosphere is present.
● Field wiring shall be in accordance with NEC (ANSI-NFPA 70) for Division 2 hazardous locations and CEC (CSA C22.1) for division 2
locations as applicable.
● The instrument must be installed, commissioned and maintained by qualified personnel trained in process automation and control
instrumentation. The installation personnel must ensure the instrument has been wired correctly according to the applicable wiring diagram.
● All location specific installation and wiring requirements (i.e., local electrical codes) must be met and maintained. Install an input
power circuit breaker or power disconnect switch and fuse near the flow meter to interrupt power during installation and maintenance.
A switch or circuit breaker is required if installation is in a hazardous area.
● The flow meter contains electrostatic discharge (ESD) sensitive devices. Use standard ESD precautions when handling the circuit
board assemblies.
● Hazardous Areas: The instrument is designed for use in hazardous areas. The approved area classification is identified on the
nameplate along with the temperature and pressure limitations. See Agency Approvals , page 3 and APPENDIX C , page 93 for a
complete listing of the instrument’s safety/hazardous areas approvals.
Order Verification
● Verify the received hardware matches the purchased hardware and application requirements. Verify the model number and part
number on the instrument I.D. tag matches the purchased model number part number.
● Review the calibration requirements as specified on the Engineering Data Sheet in the documentation package. Verify the flow,
temperature and pressure limits meet the application requirements.