ISO 16659 series provide different test methods aiming at assessing the performances of radioactive iodine traps in ventilation systems of nuclear facilities. This series deals with iodine traps with solid sorbent, mainly activated and impregnated charcoal, the most common solid sorbents used in ventilation systems of nuclear facilities, as well as other sorbents for special conditions (e.g. high temperature zeolites). ISO 16659-1 provides the general requirements to be applied for all methods of the series. The scope of this document is to provide general and generic requirements for the test method using cyclohexane (C6H12) as a tracer to determine the mechanical leakage rate of iodine trap. This reproducible method can support nuclear operators to compare the result with reference values given in safety reports. Unlike the method of radioactive methyl iodide described in ISO 16659-2, the cyclohexane field test method covered in this document does not directly give a decontamination factor for the iodine trap, but only the iodine trap performance information of an integrity test. Due to the use of the environmentally friendly test reagent of low-toxicity in the field tests, the method is mainly suitable for ventilation systems of those habitable spaces (e.g. main control rooms of nuclear power plants), and performance test of a single iodine trap before its delivery and acceptance. In addition, the method can also be used for iodine traps with activated carbon sampling canister (e.g. deep bed iodine trap Type III and Drawer iodine trap Type II).