API 520 Part 1 – Sizing and Selection of Pressure Relief Devices 1、 Para 1.1: the recommended practice applies to the sizing and selection of pressure relief devices used in refineries and related industries for equipment that has a maximum allowable working pressure of 15 psig [103kPag] or greater. 2、 What is “Steady state flow of Newtonian fluids”? 3、 Para 1.1: Pressure relief devices protect a vessel against overpressure only; they do not protect against structural failure when the vessel is exposed to extremely high temperatures such as during a fire. See API recommended Practice 521 for information about appropriate ways of reducing pressure and restricting heat input. 4、 Para 1.1: Atmospheric and low pressure storage tanks covered in API standard 2000 and pressure vessels used for the transportation of products in bulk or shipping containers are not within the scope of this recommended practice. In addition, the rules for overpressure protection of fired vessels are provided in Section I of the ASME Boiler and Pressure Vessel Code and ASME B31.1, and are not within the scope of this recommended practice. 5、 Para 1.2.1.1: Pressure relief device may be a pressure relief valve, a non-reclosing (?) pressure relief device, or a vacuum relief valve. 6、 Para 1.2.1.2: understanding the difference between a relief valve(A), a safety valve(B), a safety relief valve(C), a conventional pressure relief valve(D), a balanced pressure relief valve(E), and a pilot operated pressure relief valve(F): Valve A Actuated by Static pressure upstream Character Application Valve opens in proportion to Incompressible fluids the pressure increase over the opening pressure Rapid opening or pop action Compressible fluids Works as safety or relief Directly affected by changes in the back pressure Incorporate a bellows or other means for minimizing the effect of back pressure A pressure relief valve Larger size B C D E Static pressure upstream Spring Spring Spring F pilot 7、 Para 1.2.1.3: non-reclosing pressure relief device: a pressure relief device which remains open after operation. A manual resetting means may be provided. 8、 Para 1.2.1.4: rupture disk device is a non-reclosing pressure relief device actuated by static differential pressure between the inlet and outlet of the device and designed to function by the bursting of a rupture disk. A rupture disk device includes a rupture disk and a rupture disk holder. Attention: the definition of disk and holder 9、 Para 1.2.1.5: Pin-actuated device is a non-reclosing pressure relief valve device actuated by static pressure and designed to function by buckling or breaking a pin which holds a piston or a plug in place. Upon buckling or breaking of the pin, the piston or plug instantly moves to the full open position. 10、Para 1.2.2 Dimensional Characteristics of Pressure Relief Devices 11、Para 1.2.3 Operational Characteristics 本文来源：https://www.wddqw.com/doc/80e12cdc7f1922791788e805.html