A safety valve is a rapid opening or pop-up action pressure relief valve actuated by inlet static pressure. Safety valves are used primarily with compressible gasses. Particularly for steam and air services.
Safety valves are classified according to the lift of disk and bore of the valve. Types of safety valve are a low lift, full-lift, and full-bore safety valves.
Pressure Safety Valve - is the term used to describe relief device on a compressible fluid or gas filled vessel. For such a valve the opening is sudden. When the set pressure of the valve is reached, the valve opens almost fully.