The Ludlum Model 333-2 Beta Air Monitor, together with the included Model 333-1P Regulated Vacuum Pump, forms a complete air monitoring system. The Model 333-2 is configured for continuous sampling of airborne beta-emitters. The detection system consists of a primary pancake detector facing the upstream side of the filter paper, and a second gamma subtract pancake detector located behind and facing the back of the Primary Detector. The sampling assembly is surrounded by 5.1 cm (2 in.) of lead shielding.

                                         

The Model 333-2 has dual alarm setpoints that provide independent setting of the ALERT level (strobe) and the ALARM level (bell). Setpoints may be checked via the front-panel pushbuttons, with the controls located behind the calibration cover plate. Failure detection is provided for loss of count in the primary detector. Contact closure is provided for all three of the alarm annunciations listed above.  Dual recorder outputs, a 4-20 mA source and 0-1 volt DC, are provided.