Laundry Contamination Monitor - Model 329-32
Introduction

The Ludlum Model 329-32 Laundry Contamination Monitor is intended for automatic monitoring of both alpha and beta-gamma contamination on clothing or other light articles presumed to be free of radioactivity, or within release or reuse limits. A motor-driven steel-mesh conveyor belt carries articles between two gas proportional detector arrays. An audible alarm will sound when contamination exceeds the given alarm setpoint. A light-emitting diode (LED) array spanning the belt shows the approximate position of the alarm on the conveyor, and provides the operator with the status of the machine. A dual liquid crystal display (LCD) shows the counts and the current operating conditions, such as conveyor speed and gas flow. A security-code protected 20-key keypad also allows the changing of alarm set points, operating parameters, and other system information. The entire system is mobile, with lockable casters to prevent unwanted movement of the monitor.

Each lower and upper detector array has 16 individual gas proportional detectors, providing 32 alpha channels and 32 beta-gamma channels for a total of 64 counting channels. A spare detector array (supplied with each system) allows for easy replacement, reducing down time. The detector arrays are staggered providing an even response across the conveyor. The usable detection width is 86.4 cm (34 in.) with an overall belt width of 91.4 cm (36 in.).

All three detectors (upper, lower, and spare) slide out of the conveyor bed for cleaning and repair. The electronics is microprocessor-based, and housed in two slide-out drawers. There are two alarm levels, each fully adjustable. The first alarm level (ALERT) can pause the conveyor, stop the conveyor, allow the conveyor to continue, or re-scan. Re-scan reverses the belt to clear the probe that caused the alert, and then passes the article through the monitor again. A master yellow alert lamp will light for the duration of any ALERT. The second alarm level (ALARM) can either stop the conveyor and light the red master lamp and audio, re-scan once, twice, always, or it may continue conveyor operation and latch all alarms. Fail detection features include high-voltage failure, low count, and high background. The high voltage, conveyor belt speed, and output gas flows are monitored by the central processor. Pressing the BACKGROUND UPDATE button manually enters the background mode. Automatic background updates allow updating after the conveyor has become free of articles.