BS EN 62363:2011 pdf download – Radiation protection instrumentation — Portable photon contamination meters and monitors
5.4 Sealing For assemblies intended for outdoor use, the manufacturer shall state the precautions that have been taken to prevent the ingress of moisture.
5.5 Alarm threshold
This clause is applicable to monitors only. A monitor shall include circuits necessary for activating an alarm at one or more thresholds. The number of tripping levels shall be subject to agreement between manufacturer and purchaser. The values of alarm threshold shall be given either as percentages of the ranges or in terms of units of the display. Each alarm threshold shall be designed to allow convenient operational verification by means of test signals, radioactive sources or signal input circuitry. The range of adjustment shall be specified and the value of the alarm threshold shall be capable of being adjusted to any point within this range. It shall not be possible to incapacitate the alarm by any means such as setting the alarm thresholds beyond range limits. If a mute facility is provided it shall automatically reset when the alarm condition ceases. Alarm threshold adjustments shall not be easily accessible to the operator (for example keyswitch operated or protected password).
5.6 Pulse height thresholds Measurement assemblies should have the facility to set pulse height thresholds, which correspond to photon energy thresholds, in order to discriminate against interfering photon and/or beta radiations. Thresholds should be secure and only changed through internal controls or menus accessed by means of a password.
5.7 Measurement assembly indications
5.7.1 Meter display
The assembly should display the count rate. Displays where the quantity displayed is derived from count rate such as activity should only be used where the radionuclide mix has been characterised. In this situation, the measurement assembly shall be programmed with the relationship between the surface emission rate and total activity (or activity per unit area) of the mix, taking account of the decay efficiency of the radionuclide(s), the surface emission rate response and the source efficiency. The manufacturer shall state the method used to program the assembly with this relationship. Where the assembly indicates activity, the manufacturer should indicate the assumed surface area of the activity. The unit of activity shall be the Becquerel (Bq). For digital displays, an additional pseudo-analogue graphical indication should be provided which shows the count rate (or activity) in terms of the proportion of the maximum of the range indication, for example a bargraph. Where an instrument has a digital display, a feature shall be provided to check that all segments of the display are operational.
Where linearly scaled displays are used for this application, autoranging functionality should also be provided.
5.7.2 Audible indication An audible indication of count rate shall be provided. There shall be a facility for muting this indication. Where the equipment has been designed for use where noise levels could be high, provision shall be made for the use of a head set.
5.7.3 Additional indication Indication shall be given of operational conditions in which the indication is not correct (within the specifications of this standard), for example low battery or detector failure.
5.7.4 Monitors All the characteristics described in 9 9 H 5.7.1 , 1 0 0 H 5.7.2 and 1 0 1 H 5.7.3 are also required for monitors. In addition to the audible indication of count rate (or activity) above, there shall be either an audible indication of contamination above a certain preset value or visual indication. Although the audible indication may be produced by the same transducer as the indication of count rate, it shall be distinctly different from this indication.
5.8 Effective range of measurement For logarithmically scaled assemblies, the effective range of measurement shall be from below one third of the least significant decade to full scale. For digitally scaled assemblies, the effective range of measurement shall be from the start of the second least significant digit to the maximum of the rated range of measurement.