ST75 thermal flow meter for precise air flow measurement

The ST75 Series air/gas flow meter from Fluid Components International
(FCI) provides precise direct mass flow measurement for building, plant and
process engineers responsible for managing large HVAC and other process cooling
equipment systems. The energy efficiency of these systems relies on precision
air flow metering in large commercial buildings, manufacturing plants and
industrial processes.

Designed to deliver superior accuracy, repeatability and dependability,
the ST75 Series air/gas flow meter features an advanced solid-state thermal
dispersion mass flow sensing element for years of trouble-free service
measuring air flow in chiller systems and duct work.

Available from AMS Instrumentation and Calibration, the ST75 flow meter operates
over a wide air flow range that also includes mixed gas environments from 0.07
to 950 NCMH, depending on line size. For variable demand cycles due to weather
or production requirements, the ST75 meter is factory pre-set to 100:1
turndowns. With built-in process temperature compensation for accuracy, the
precision ST75 flow meter maintains consistent performance in high temperature
climates and rugged plant environments. It features highly dependable accuracy
to ±1% of reading with ±0.5% repeatability in line sizes from 6 to 51 mm.

The precision flow element with a no-moving parts design employs
platinum RTD sensors embedded in equal mass thermowells with its microprocessor
electronics calibrated to laboratory standards for air and a wide variety of
other gases. This no-moving parts design provides extra reliability where
process safety is a concern.

FCI’s ST75 flow meters are ideal for crowded equipment areas in HVAC
mechanical rooms or on the factory floor.

Key features include choice of inline or insertion mounting
configurations with remote mounting capabilities for hazardous plant
environments; built-in Vortab flow conditioner where lack of pipe straight-run
is a potential issue (model ST75AV); transmitter with a full digital display mountable
up to 15 metres away from its thermal mass flow sensor in piping or ductwork and
connected via two 0.50-inch FNPT or M conduit connections; fully scalable dual
4-20mA standard outputs user assignable to flow rate and/or temperature and a
0-1kHz pulse output of total flow; and input power with either 18 to 36 Vdc or
85 to 265 Vac, with or without a built-in LCD digital display.

The durable ST75 flow meter can withstand process temperatures from -18¡C
to 121¡C. It operates at pressures up to 16.5 bar (g) with a standard t-fitting
(NPT female) process connection. With a tube process connection, the meter
withstands 41 bar (g).

Offering direct flow measurement for higher performance at a lower cost
with proven thermal dispersion technology, the ST75 flow meter eliminates the
need for additional pressure and temperature sensors, flow computers, or devices
that are required with orifice plates, Venturis, Vortex shedding, and other
volumetric meters. The ST75 meter also requires virtually no maintenance.

The ST75 Series electronics are housed in a rugged, IP67 rated enclosure
with dual conduit ports in either NPT or M20 threading. The models ST75A and
ST75AV include HART as well as NAMUR compliant 4-20 mA outputs and SIL
compliance rating. The complete instrument carries global Ex agency approvals
for Division l/Zone 1 installations.

For further information, please visit the AMS Instrumentation and
Calibration website,
or call 03-9017 8225, or Freecall (NZ) 0800 442 743.

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