NOTE Nominal sizes (DN), nominal pipe sizes (NPS), nominal pressure (PN) and Classes are covered in ISO 28921‑1.
ISO 28921-2:2015 does not evaluate valve actuators unless they are integral part of the valve. Valves during testing can be operated manually or an actuator can be used during the testing. The effect of cold gas vapours during testing is taken into consideration in particular if the actuator is mounted directly over the test stand with the cold gases engulfing the actuator.
ISO 28921-2:2015 does not apply to valves for cryogenic services, designed in accordance with ISO 21011, used with cryogenic vessels.