ISO 19973-4:2007 provides test procedures for assessing the reliability of pneumatic pressure regulators 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 without repairs, but exclude outliers.
ISO 19973-4:2007 applies to manually adjustable and remote-piloted pressure regulators, both relieving and non-relieving. ISO 19973-4:2007 does not apply to pressure regulators that have a permanent bleed.
ISO 19973-4:2007 also specifies test equipment and failure criteria (threshold levels) for tests to assess the reliability of pneumatic pressure regulators.