Safety Valve

safety valve, device attached to a boiler or other vessel for automatically relieving the pressure of steam before it becomes great enough to cause bursting. The common spring-loaded type is held closed by a spring designed to open the valve when the internal pressure reaches a point in excess of the calculated safe load of the boiler. Safety valves are installed on boilers according to strict safety regulations.

---

safety valve

a valve in a pressure vessel that allows fluid to escape when a predetermined level of pressure has been reached

---

safety valve [′sāf·tē ‚valv]

(mechanical engineering)

A spring-loaded, pressure-actuated valve that allows steam to escape from a boiler at a pressure slightly above the safe working level of the boiler; fitted by law to all boilers. Also known as safety relief valve.

---

Safety valve

A relief valve set to open at a pressure safely below the bursting pressure of a container, such as a boiler or compressed air receiver. Typically, a disk is held against a seat by a spring; excessive pressure forces the disk open (see illustration). Construction is such that when the valve opens slightly, the opening force builds up to open it fully and to hold the valve open until the pressure drops a predetermined amount. This differential or blow-down pressure and the initial relieving pressure are adjustable. See Valve

---

pressure relief valve

In a pressure tank for water storage, a pressure-actuated safety valve that is designed to open and relieve pressure automatically if the pressure within the tank exceeds the value for which it was designed to operate safely.

---

Safety Valve 

a device to ensure the safety of equipment operating under high liquid, gas, or steam pressure when damage to the equipment may result from exceeding the established operating pressure. Safety valves are installed on steam boilers, compressed air receivers, and various technical devices and pipelines operating under pressure. When the pressure in the system rises above the permissible level, the safety valve opens and automatically releases the excess of the working substance, thus preventing an accident. When the pressure is reduced to the permissible level, the safety valve automatically closes. In the USSR, areas of mandatory use, installation, and servicing of safety valves are determined by special laws (seeBOILER INSPECTION).

Safety valves are divided into those loaded by weights and those that are spring-loaded. In the former, the stopper is loaded directly (for low pressures) or by a lever. In spring-loaded safety valves, the pressure of the medium on the stopper is opposed by the force of a spring.

G. G. MIRZABEKOV