ISO 19973-3:2015 provides test procedures for assessing the reliability of pneumatic cylinders with piston rod, both single-acting and double-acting, by testing and the methods of reporting the results of testing. General test conditions and the calculation method are provided in ISO 19973-1. The methods specified in ISO 19973-1 apply to the first failure, as obtained with the three-point moving average (3PMA) method, without repairs, but excluding outliers.The lifetime of pneumatic cylinders is usually given in number of cycles or in kilometres. Therefore, whenever the term "time" is used in this part of ISO 19973-3:2015, this variable is to be understood as cycles or kilometres.ISO 19973-3:2015 also specifies test equipment and threshold levels for tests to assess the reliability of pneumatic cylinders with piston rods.ISO 19973-3:2015 is intended to be applied to pneumatic piston rod cylinders that conform to ISO 6430, ISO 6432, ISO 15552, and ISO 21287; however, pneumatic piston rod cylinders that do not conform to these International Standards but are used in the same range of operating conditions can be tested in accordance with one of the classes defined in Tables 1 and 2.