iCAM Alpha/Beta Air Monitor  

Removable, card-mounted filters
Automatic self-initialization and operation on power on
Electronic air flow rate measurement, with high and low flow alarms
Continuous total airflow recording and reporting
User-set alarms with local and remote reporting
Simple/automated checks for calibration, gain and spectrum shape
Software package for full iCAM configuration by local computer or via a network
Fault diagnostics show on the local display and across the network
RS-485 and RS-232 communication interfaces
One-week data storage with detailed event log
Data is RS-232 and RS-485 transferable to Microsoft Excel
Thirty minute protection of full functionality by built-in battery backup
Five years protection of configuration memory
Measurement:
Continuous monitoring of both alpha and beta activity in air
Alpha MCA spectroscopy and separate beta discrimination
Good low energy beta detection
Auto-adaptive spectrometric compensation for radon/thoron
Static gamma background compensation with single CAM PIPS detector
Fully compensated activity alarms
Three activity levels for primary alarms
Additional Quick and Long Alarm
Discharge and discharge rates for duct/stack monitoring
Options
Trolley mounted system
Dual CAM PIPS detector version with dynamic gamma compensation
Full-function area gamma alarm monitor capability using the optional G64 detector
I/O expansion option provides RS-422 pulse train outputs (compatible with previous Harwell instruments), and also current loop input, optoelectronic outputs and other I/O
Benefits
Engineering:
A light and compact integrated unit, which is robust, simple to use and easy to maintain
All the required facilities for alpha and beta monitoring, alarms, data logging, communications and setup
Sensitive detection of alpha and beta particles plus intelligent adaptive algorithms, for fast, accurate alarms, resulting in high levels of protection and low false alarm rates
Adaptive spectrometry algorithms and automated checks for high tolerance to variations in background conditions and extended time between filter changes
Extra alarm facilities for improved management of safety
Description
CANBERRA§s intelligent alpha/beta Continuous Air Monitor (iCAM) provides robust and reliable monitoring of airborne alpha and beta particulate activity in the workplace.
It acts as a simple alarming monitor for operators while measuring airborne activities in real time with the sophistication required to provide low false alarm rates and high protection levels. At the same time it provides automated facilities which assist supervisors to conduct detailed setup and operational overview.

The iCAM measures airborne alpha and beta particulate activity with radon/thoron alpha and beta background compensation. It also provides static or dynamic compensation of beta measurements for gamma background depending on the choice of detector type.

Air is drawn through the instrument by means of an external pump or vacuum system, and airborne particulate material is deposited on the removable card-mounted filter. The filter is monitored by a robust CANBERRA CAMS PIP (passivated ion-implanted planar silicon) radiation detector, which allows simultaneous measurement of both alpha and beta radioactivity in the material deposited on the filter. The air flow is measured directly and reported by the instrument. The design of the airflow system is optimized to ensure high air sampling efficiency and high transmission of particles to the filter. The iCAM has a high detection efficiency for both alpha and beta particles and provides a good sensitivity for low energy beta detection.

Measurement results are presented on the high-visibility graphical display on the instrument§s front panel. User setup and diagnostics are via the local keypad and the graphical display which provide a natural user interface. Results may also be reported via the RS-232 or RS-485 network connections to a local computer or plant surveillance system. Each instrument stores historical data, typically from the previous seven days, which may also be transmitted by network if required. The historical data includes not only activity readings, updated every five minutes in normal operation, but also alarms, filter changes and user interactions. Each event is logged with its date and time.

The iCAM Primary Alarm uses measurements taken over a user selectable interval of typically five minutes, and this data is updated as rolling average every 15 seconds. Alpha, beta and gamma (where applicable) measurement values are each tested against user-set alarm levels. There are three separate sets of three alarm levels, one set of three for each of the alpha, beta and gamma measurement variables. Additional defence against larger emissions of activity in a short time is provided by the Quick Alarm, for which decisions are made on the new data accumulated every 15 seconds.

Finally, iCAM also provides a Long Term Alarm (Chronic Activity Alarm). Here the lowest level alarm may be user-allocated to data accumulated over a long time interval, typically >30 minutes, so that the most sensitive measurements can be achieved. All the alarms are fully compensated for the backgrounds from gamma radiations and from radon/thoron daughter activities.

In addition, any alarms may be indicated locally by visual and audible signals, remotely by relay circuits, or centrally by connection to a suitable monitoring network. Alarm events are also archived.

Hardware
The iCAM instrument is packaged in a rugged steel enclosure which provides IP42 environmental protection and EMC screening. The front panel carries the local controls and indicators, including the high visibility graphical display, the local keypad and the various indicator lights. The RS-232 connector and the alarm sounder are positioned in the bottom third of the front panel. The air inlet and alarm beacons are mounted on top of the instrument.

When the power supply is switched on, the instrument will perform initialization tests and begin normal operation without any operator intervention. It will begin providing valid measurements within 15 seconds after starting normal operation. It will then update measurements at 15 second intervals, whatever the user-set counting interval.

Air is drawn into the instrument at a preset rate, within the range 15-60 L/min (0.5-2.1 ft3/min), typically about 37 L/min (1.3 ft3/min), and particulate material is deposited on a removable filter card. The instrument may be fitted with an adapter for the attachment of a 25 mm (1 in.) pipe. An airflow regulator valve is provided as an option, and the choice of air outlet position may be adopted from either of two connectors: one on top of and one on the bottom of the instrument. The airflow rate is measured directly on board and its value is used to calculate concentration values and integrated concentration values. Low and high flow alarm values can be set by the user. The total air flow since last reset is recorded and reported.