ASME PTC 25-2018 pdf free

ASME PTC 25-2018 pdf free.Pressure Relief Devices Performance Test Codes.
The purpose of this Section is to define pressure relief devices and their functional and operational characteris• tics and standardize the terminology covering such devices, their characteristics, and testing methods. It also includes a description of terms and symbols used in this Code. These definitions and terms shall take precedence should there be any discrepancy with the referenced material.
2-2 GENERAL
bench testing: testing of a pressure relief device on a test stand using an external pressure source with or without an auxiliary lift device to determine some or all of its operating characteristics.
field festing: testing of a pressure relief device installed on a system to determine some or all of its operating characteristics. It may be either of the following nwthods:
(a) in-place testing: testing of a pressure relief device installed on but not protecting a system, using an external pressure source, with or without an auxiliary lift device to determine some or all of its operating characteristics.
(b) in-service testing: testing of a pressure relief device installed on and protecting a system, using system pressure or an external pressure source, with or without an auxiliary lift device to determine some or all of its operating characteristics.
flow capacity testing: testing of a pressure relief device to determine its operating characteristics, including measured relieving capacity.
pressure relief device: a device designed to prevent pressure or vacuum from exceeding a predetermined value in a pressure vessel by the transfer of fluid during emergency or abnormal conditions.
2-3 TYPES OF DEVICES
2-3.1 RecLosi ng Pressure-ReLieving Devices
pressure relief valve (PRV): a pressure relief device designed to actuate on inlet static pressure and reclose after normal conditions  have been restored. It may be one of the following types and have one or more of the following design features:
(a) low-lift PRV: a pressure relief valve in which the actual discharge area is the curtain area.
(b) full-lift PRV: a pressure relief valve in which the actual discharge area is the bore area.
(c) restricted-lift PRV: a full-lift pressure relief valve whose lift is restricted such that the capacity is reduced proportionally to the ratio of restricted-lift to full-lift.
(d) reduced bore PRV: a pressure relief valve in which the flow path area below the seat is less than the flow area at the inlet to the valve.
[e) full-bore PRV: a pressure relief valve in which the bore area is equal to the flow area at the inlet to the valve,and there are no protrusions in the bore.0 direct spring-loaded PRV: a pressure relief valve in which the disk is held closed by a spring.
[g) pilot-operated PRV: a pressure relief valve in which the disk is held closed by system pressure, and the holding pressure is controlled by a pilot valve actuated by system pressure.ASME PTC 25 pdf free download.