name="_Hlk108024231">Engineers in a range of industries responsible for gas dosing and gas injection in small line batch and continuous processes will benefit from the dependable thermal dispersion sensing technology employed by the versatile ST75 series air/gas flow meter from Fluid Components International (FCI)
The compact ST75 series air/gas flow meter, which is available in both insertion and inline configurations, is the ideal flow measurement solution for gas dosing and injection in tight, crowded equipment areas. Gases are dosed or injected in a wide range of industries including: advanced materials, biomedical, electronics, food/beverage, mining/metals, oil/gas production, petrochemical refining, plastics, pharmaceuticals, pulp/paper, water treatment and many more.
All gas dosing and injection processes have one important thing in common: the gas flow rate and the totalized flow of gas must be measured with high accuracy and repeatability for batch quality control and low cost operational efficiency. The precision ST75 flow meter’s solid-state thermal dispersion mass flow sensing element with platinum resistance temperature detectors is housed in equal mass thermowells for years of trouble-free service. It measures virtually any gas or gas mixture, and it can be calibrated to measure gases over a flow range from 0.04 standard cubic feet per minute (SCFM) to 559 SCFM (0.07 normal cubic meters per hour (NCMH) to 950 NCMH), depending on line size, which is useful in low-flow applications requiring small doses.
The model ST75 flow meters are designed with a choice of mounting configurations. They feature a full digital display and are also available with optional transmitter remote mounting capabilities for hazardous plant environments. The remote transmitter can be mounted up to 100 feet (30 meters) away from its thermal mass flow sensor in piping or ductwork and connected via two 0.50 inch FNPT or M conduit connections.
For tube service in a 0.25 inch line, the compact meter’s round transmitter is 3.28 inches wide and stands only 5.7 inches above the centerline of the flow tube. Its relatively small footprint makes it simpler to add measuring points where close control of the process is desirable, such as in gas dosing and gas injection applications.
Where crowded equipment layouts exist and compromise straight pipe runs for accurate flow measurement with other technologies, the Model ST75AV meter features a built-in Vortab flow conditioner. Nearby pumps and valves that affect the accuracy of other meter technologies are no problem with the built-in Vortab flow conditioners, which create a regular smooth flow profile in the pipe for dependable flow measurement.
Fully scalable dual 4 mA to 20 mA standard outputs are user assignable to flow rate and/or temperature and a 0 kHz to 1 kHz pulse output of total flow. Two-way HART bus communications are available with the Models ST75A and ST75AV. The instrument can be ordered for input power with either 18 V DC to 36 V DC or 85 V AC to 265 V AC.
The ST75 flow meter withstands process temperatures from 0° F to 250° F. It operates at pressures up to 240 psig (16.5 bar) with a standard t-fitting (NPT female) process connection. With a tube process connection, the meter withstands 600 psig (41 bar).
The meter’s electronics are housed in rugged, IP67 rated enclosure with dual conduit ports in either NPT or M20 threading. The models ST75A and ST75AV include HART or Modbus as well as NAMUR compliant 4 mA to 20 mA outputs and SIL compliance rating. The complete instrument carries global Ex agency approvals for Division l/Zone 1 installations.
When used in variable demand cycles due to small batch or other continuous process production requirements, the ST75 flow meter is factory preset to 100:1 turndowns. It features highly dependable accuracy to ±1% of reading with ±0.5% repeatability in line sizes from 0.25 to 2 inches.
Its flow element features a rugged, no-moving parts design for superior reliability. This unique design provides extra confidence where process safety is a big concern with other types of meter technologies, which rely on movable parts that can break over time in high turndown applications. These incidents can send dangerous meter debris crashing through pipes conveying hazardous combustible gases.
