Flow System

All flow rates, including sheath flow for both polarities and sample flow (either single or separate), are measured using Venturi tubes and differential pressure sensors. These sensors are calibrated at Airel.

Blowers are automatically adjusted via a software PID controller, utilizing flow and barometric sensors to maintain constant mobility analysis and sampling volume flow rates.

Sheath Air Filters

The mobility analyzer's sheath air is recirculated from the exhaust after cleaning by a dedicated sheath air filter. Since only charged particles need to be removed, a simple, easily cleanable electric filter is employed, eliminating the need for replacement when clogged. Each analyzer column features a separate sheath air filter.

The filter typically operates at approximately 4.5 kV. Prolonged periods without cleaning increase the likelihood of internal fibers or dirt coronating and generating charged particles, which can disrupt NAIS measurements. The severity of this disturbance depends on the corona discharger's polarity and location. Refer to Sheath Air Filter Cleaning for more information.