The ST100 Series Thermal Flow Meter from Fluid Components International (FCI), available from AMS Instrumentation & Calibration, is designed to help operators provide precision mass flow measurement in wastewater treatment operations.

Digester waste gas is a combination of methane (CH4) and carbon dioxide (CO2) with a small percentage of other trace gases.

Its gas composition can vary with the process and temperature, but a typical average is in the range of 65% (±5%) CH4 and 35% (±5%) CO2.

Digester gas is also a moist and dirty gas, typically containing entrained hydrogen sulphides, which condense and deposit on pipe walls.

If the gas is harvested for use as fuel in a CHP or cogen system, the amount of gas being sent to the engine is a key control variable.

Further, if any gas is released or flared, because both methane and carbon dioxide are known polluting greenhouse gases (GHG), local environmental regulations typically mandate reporting of the quantity of gases emitted or flared.

With no moving parts and simple insertion-style design, and global HazEx approvals, the ST100 Flow Meter suits digester gas flow measurement.

It can be calibrated for the specific digester gas mix composition and processes temperature conditions in flow ranges from 0.07 NMPS to 305 NMPS and with accuracy to ±0.75 percent of reading, ±0.5 percent of full scale.

ST100’s constant power thermal dispersion, mass flow technology, has proven useful in applications with moist, dirty gases. It can be installed in the pipe with a simple, retractable compression fitting or through a ball valve for easy access.