All About Fire Safety Valves Professionalمنذ 10 أشهر - Multimedia - Saïda - 200 الآراء
How Fire Safety Valves Work
A fire safety valve aims to keep ignitable fluids away from a flame. These fire gate valve close when exposed to heat, separating a flammable liquid from the heat source. They close in the midst of overheating of the pipeline, brought on by fire or similar events. The obligation to use fire safety valves is subject to any tenets, regulations, and laws concerning the unique methodology, plant, pipeline, or vessel.
Fire-safe ball valves use a combination of a floating ball, graphoil seals, and metal-to-metal seating to provide tight shut-off while preventing external stem leakage. In normal working conditions, the ball rests against two seats, ensuring bubble-tight closure. When the valve is exposed to a temperature above the limits the seats can withstand (for example, +450°F), the seats become deformed and are subject to extrusion. When the seats have been completely destroyed, the ball in the valve will come to rest firmly against the end cap, producing a metal-to-metal closing. Stem seals, which have high temperature-resistant properties, further restrict leakage in conjunction with a blow-out-proof anti-static stem, so that the flammable fluid stays separate from the heat source that may ignite it.
A fire-safe valve may also be made up of four main mechanisms: a spring pack, a trigger assembly, mounting hardware, and a fusible link. The components work in unison to close the valve should a fire be detected within a facility. The fusible link is the key part of the assembly. It keeps the valve open by maintaining tension on a spring pack through the trigger assembly. When a fire breaks out, the fusible link separates once it is heated to a certain high temperature, which releases the spring pack and allows it to close the valve.
A fire-safety valve with fusible links has a primary drop-tight seat, usually made of TFE, along with a second seat made of metal for isolation in a fire. The secondary seat also has graphite seals for further protection. This means that the shut-off valves can be paired with any quarter-turn ball valve, butterfly valve, or fire ball valve.