This part of IEC 60761 is applicable to equipment intended for the simultaneous, delayed or discrete sequential measurement of radioactive iodine in all forms. When the effluent is sampled for measurement, iodine bound on aerosols is generally collected on a prefilter which should be analyzed separately in a laboratory to provide a complete measurement. It is applicable to equipment designed to fulfill the following functions: - the measurement of the volumic activity of iodine and compounds of radioactive iodine in gaseous effluents or of the released iodine total activity; - the actuation of an alarm signal when either a predetermined concentration or a predetermined total released activity due to iodine or its compounds is exceeded. This equipment is intended for measurement over a wide range of activity in the presence of other radionuclides in the gaseous effluent, including naturally occurring radioactive nuclides. Discrimination against other radionuclides can be important in measuring low levels of radioactive iodine. This standard considers both the use of iodine collection media such as activated charcoal and the direct measurement of iodine in stacks or ventilation ducts. The object of this standard is to lay down specific standard requirements, including technical characteristics and general test conditions, and to give examples of acceptable methods for iodine monitors as defined in clause 4. The general requirements, technical characteristics, test procedures, radiation characteristics, electrical, mechanical, safety and environmental characteristics are given in IEC 60761-1. Unless otherwise stated, these requirements apply in this standard.