Tapered element oscillating microbalance

A tapered element oscillating microbalance (TEOM) is an instrument used for real-time detection of aerosol particles by measuring their mass concentration.

It makes use of a small vibrating glass tube whose oscillation frequency changes when aerosol particles are deposited on it increasing its inertia.

Incoming particles are deposited on a filter at the tip of the tube, and the added mass causes a change in its oscillation frequency which is detected electronically.

[4] Under ideal conditions, TEOM is just as accurate as the standard reference method, but its sensitivity presents complications for use for environmental monitoring in urban areas.

Prior to the introduction of CPDMs, dust particles collected on a filter needed to be analyzed in a laboratory, leading to a delay of weeks in obtaining results.

Continuous monitoring allows miners to take corrective action such as moving to another area or changing their activities if dust levels exceed exposure limits.

An diagram showing the airflow through the machine. The air flows from a sampling inlet to a flow splitter, where some of the flow goes to a heated sensor unit containing a tapered element mass transducer connected to an amplifier and frequency counter, while the rest goes to a bypass flowline. Both lines then goe in parallel to in-line filters and mass flow controllers, before rejoining at a vacuum pump leading to exhaust.
A diagram showing the operation of a tapered element oscillating microbalance instrument.
A photograph of a black apparatus with a digital readout.
A personal dust monitor
A continuous personal dust monitor at use in a mine