Type of Pressure Relief Device

Two types of pressure relief devices are available, safety valves and relief valves. Although these terms are often used interchangeably, there is a difference between the two. Safety valves are used with gases. The disk overhangs the seat to offer additional thrust area after the initial opening. This fully opens the valve immediately, giving maximum relief capacity. These are often called pop-off safety valves. 

The District Engineering Inspectors Report confirmed that the machine was completely isolated and the ammonia system was not protected by a safety valve or any type of pressure-relief device. The cause of the accident was the presence of the steam hose underneath the equipment to melt the ice on the drain valve or to help evacuate the system. The inspectors report could not determine if these preparations were intentional or accidental. [5]... 

This chapter describes the various types of pressure relief devices used in the compressed gas industry and the standards developed to describe their design criteria, performance characteristics, and applications. The sections covered are ... 

All four of the following types of pressure relief devices for compressed gas storage contain-... 

Pressure relief valve A type of pressure relief device designed to relieve excessive pressure and to reclose and reseal to prevent further flow of fluid from the cylinder after reseating pressure has been achieved. 

Pressure relief and safety devices have uniquely contributed to the safe utilization of compressed gases. Chapter 7 will provide insights into the evolution and systematic application of the various types of pressure relief devices now in use. Likewise, the systematic use of cylinder valve connections, connections to ancillary equipment, and bulk transfer connections has evolved into a methodology that is intended to help ensure that the proper gas is actually connected for the intended application. This methodology,... 

All four of the following types of pressure relief devices for compressed gas storage containers are similar to those described and illustrated in the preceding section concerning devices for cargo and portable tanks ... 

Types of pressure relief devices used on oxygen cylinders include the CG-1 rupture disk, the CG-4 and CG-5 combination rupture disk/fusible plug devices, and the CG-7 pressure relief valve. [14] See CGA S-1.1, Pressure Relief Device Standards—Part 1— Cylinders for Compressed Gases, for further information and requirements. 

S-1,1 Pressure Relief Device Standards Part l Cylinders for Compressed Gases, Minimum recommended requirements for pressure relief devices for use on TC/DOT cylinders having water capacities of 1000 lb or less. Describes the various types of pressure relief devices, their design, construction, and application for various cylinders. Also covers relief device test and maintenance requirements. (36 pages)... 

In this chapter, following topics will be discussed type of pressure relief devices, their characteristics, ASME code PRD set pressure, maximum operating pressure, contingency analysts, pressure reliefvalve and rupture disk sizing, pressure relief valve inlet/outlet piping sizing, Eind PRD selection. 

II, Type of Pressure Relief Device Commonly used PRD are explained in this section. 

The following subsections describe the guidelines often used in selecting the type of pressure relief device. 

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