How does the APM 460DX compensate for dust loading on the filter ?
The APM 460DX model RDS incorporates an automatic flow controller which constantly monitors the flow rate through the filter paper. Initially when the filter paper is relatively clean part of the Blower capacity is bypassed through a valve. As the filter gets choked and offers greater resistance the flow controller dynamically adjusts the bypass air flow to allow a greater suction capacity of the Blower to operate through the filter. As such the flow controller maintains a constant air sampling rate through the filter.