Thermal mass flow meter provides precise gas line control for ovens and furnaces

The advanced, compact ST75 air/gas flow meter from Fluid Components International (FCI), which measures fuel gas, process gas, inert gas, waste gases and air in small line sizes, is suitable for optimising natural gas flow control for industrial ovens, heat chambers and furnaces to reduce process and plant fuel costs.

Natural gas fuelled industrial ovens, heat chambers and furnaces are used in a wide variety of heating process applications. Two of the most common types of industrial ovens are the batch oven and the conveyor oven. Batch ovens support variable production load sizes, volumes and multiple temperature profiles where a high degree of process flexibility is desirable. Conveyor ovens, on the other hand, support highly repeatable temperature profiles with uniform, predictable volumes.

No matter the type of oven, heat chamber or furnace, they all benefit from the precise control of natural gas flow. FCI’s ST75 flow meter helps process and plant engineers more accurately control their complex heating processes to optimise rise time, which lowers gas consumption and minimises plant energy costs. In addition, reducing natural gas consumption shrinks a plant’s carbon footprint to protect the environment.

The ST75 is equally well suited for low flow and high flow operations in industrial ovens and operates over a wide flow range, from 0.01 to 559 SCFM (0.01 to 950 NCMH) depending on line size. For variable process conditions, the ST75 is factory preset to a wide turndown range at 10:1 to 100:1.

With built-in temperature compensation, the ST75 also maintains consistent performance in rugged, hot industrial process environments. It features accuracy to ±2% of reading with ±0.5% repeatability over varying process temperatures in line sizes from 6 to 51 mm. With a Vortab flow conditioner added as a spool piece, the Models ST75V or ST75AV are applicable for installations with limited straight-runs or for operating in transitional flow ranges with accuracy of ±1% reading, ±0.5% full scale.

The ST75 flow meter’s precision flow element has a no-moving parts design that employs platinum RTD sensors embedded in equal mass thermowells with microprocessor electronics calibrated to laboratory standards for a wide range of gases.

Ideal for ovens, heat chambers and furnaces, the ST75 features remote mounting capabilities for hazardous or crowded plant environments. The remote-mount transmitter, which includes a full digital display, can be mounted up to 15 m away from its thermal mass flow sensor in the process piping and connected via two 12.5 mm FNPT or M conduit connections.

The ST75 flow meter’s fully scalable dual 4–20mA standard outputs are user-assignable to flow rate or temperature and a 0–1 kHz pulse output of total flow. The instrument can be ordered for input power with either 18–36 VDC or 85–265 VAC, with or without a built-in LCD digital display.

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 other devices that are required with orifice plates, Venturis, vortex shedding, and other volumetric meters. The ST75 also requires virtually no maintenance for both a low installed cost and low lifecycle cost.

The FM and CSA approved ST75 flow meter is enclosed in a rugged, all-metal, dust- and water-resistant NEMA Type 4X (IP66) rated package designed for Class 1, Div 1 hazardous area installations and includes a rugged sensing element constructed with all-welded 316 stainless steel and Hastelloy-C tips. ATEX/IEC approvals include: Zone 1, II 2 G Ex d IIC T6-T3; II 2 D Ex tD A21, IP67 T90°–T300°.