Biomethane-optimised mass flowmeter

FCI’s ST51 flowmeter is designed to measure digester gas, biogas and other methane-composition biofuel gases as well as natural gas. FCI precision calibrates all ST51 flowmeters in its NIST-traceable flow lab to match the gas composition of the user’s digester system and under the specific flow conditions of the user’s digester system.

The ST51 flowmeter features a thermal mass flow element with flow accuracy to +1% of reading over a broad flow range from 0.3 to 400 SFPS (0.08 to 122 mps) and repeatability of +0.5% of reading. The flow element is available for use in line sizes from 51 to 610 mm diameters and the unit operates over a wide turndown range of 100:1.

The ST51’s thermal mass flow sensing element features a no-moving-parts design, with no orifices to clog or foul, which makes it suitable for service in wet, dirty and explosive gas environments and also includes built-in temperature compensation circuitry. The flow element is constructed with a 316L stainless steel body and Hastelloy C-22 thermowell sensors to resist corrosion in digester gas pipelines.

The ST51 flowmeter operates from -18 to 121°C and withstands pressures up to 34 bar (g). It is suitable for hazardous environments with approvals that include: FM, CSA/CRN, ATEX IECeX and IP67.

Dual 4-20 mA analog outputs are user-assignable to flow rate and/or temperature and there is a 0-1 kHz pulse output for totalised flow. The transmitter’s digital communications include an RS232C port, and, with units that have the digital display option, there is a wireless IR link for PDA use.