The Collaborative International Dictionary
Relief \Re*lief"\ (r?-l?f"), n. [OE. relef, F. relief, properly, a lifting up, a standing out. See Relieve, and cf. Basrelief, Rilievi.]
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The act of relieving, or the state of being relieved; the removal, or partial removal, of any evil, or of anything oppressive or burdensome, by which some ease is obtained; succor; alleviation; comfort; ease; redress.
He sees the dire contagion spread so fast, That, where it seizes, all relief is vain.
--Dryden. -
Release from a post, or from the performance of duty, by the intervention of others, by discharge, or by relay; as, a relief of a sentry.
For this relief much thanks; 'tis bitter cold.
--Shak. That which removes or lessens evil, pain, discomfort, uneasiness, etc.; that which gives succor, aid, or comfort; also, the person who relieves from performance of duty by taking the place of another; a relay.
(Feudal Law) A fine or composition which the heir of a deceased tenant paid to the lord for the privilege of taking up the estate, which, on strict feudal principles, had lapsed or fallen to the lord on the death of the tenant.
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(Sculp. & Arch.) The projection of a figure above the ground or plane on which it is formed.
Note: Relief is of three kinds, namely, high relief ( altorilievo), low relief, ( basso-rilievo), and demirelief ( mezzo-rilievo). See these terms in the Vocabulary.
(Paint.) The appearance of projection given by shading, shadow, etc., to any figure.
(Fort.) The height to which works are raised above the bottom of the ditch.
--Wilhelm.-
(Physical Geog.) The elevations and surface undulations of a country.
--Guyot.Relief valve, a valve arranged for relieving pressure of steam, gas, or liquid; an escape valve.
Syn: Alleviation; mitigation; aid; help; succor; assistance; remedy; redress; indemnification.
Wiktionary
n. A safety valve that relieves pressure when it becomes high but before it becomes dangerous.
WordNet
n. a valve in a container in which pressure can build up (as a steam boiler); it opens automatically when the pressure reaches a dangerous level [syn: safety valve, escape valve, escape cock, escape]
Wikipedia
Relief valve may refer to:
- Relief valve
- Safety valve
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The pressure relief valve (PRV) is a type of valve used to control or limit the pressure in a system or vessel which can build up for a process upset, instrument or equipment failure, or fire. The pressure is relieved by allowing the pressurised fluid to flow from an auxiliary passage out of the system. The relief valve is designed or set to open at a predetermined set pressure to protect pressure vessels and other equipment from being subjected to pressures that exceed their design limits. When the set pressure is exceeded, the relief valve becomes the " path of least resistance" as the valve is forced open and a portion of the fluid is diverted through the auxiliary route. The diverted fluid (liquid, gas or liquid–gas mixture) is usually routed through a piping system known as a flare header or relief header to a central, elevated gas flare where it is usually burned and the resulting combustion gases are released to the atmosphere. As the fluid is diverted, the pressure inside the vessel will stop rising. Once it reaches the valve's reseating pressure, the valve will close. The blowdown is usually stated as a percentage of set pressure and refers to how much the pressure needs to drop before the valve reseats. The blowdown can vary from roughly 2–20%, and some valves have adjustable blowdowns.
In high-pressure gas systems, it is recommended that the outlet of the relief valve is in the open air. In systems where the outlet is connected to piping, the opening of a relief valve will give a pressure build up in the piping system downstream of the relief valve. This often means that the relief valve will not re-seat once the set pressure is reached. For these systems often so called "differential" relief valves are used. This means that the pressure is only working on an area that is much smaller than the openings area of the valve. If the valve is opened the pressure has to decrease enormously before the valve closes and also the outlet pressure of the valve can easily keep the valve open. Another consideration is that if other relief valves are connected to the outlet pipe system, they may open as the pressure in exhaust pipe system increases. This may cause undesired operation.
In some cases, a so-called bypass valve acts as a relief valve by being used to return all or part of the fluid discharged by a pump or gas compressor back to either a storage reservoir or the inlet of the pump or gas compressor. This is done to protect the pump or gas compressor and any associated equipment from excessive pressure. The bypass valve and bypass path can be internal (an integral part of the pump or compressor) or external (installed as a component in the fluid path). Many fire engines have such relief valves to prevent the overpressurization of fire hoses.
In other cases, equipment must be protected against being subjected to an internal vacuum (i.e., low pressure) that is lower than the equipment can withstand. In such cases, vacuum relief valves are used to open at a predetermined low pressure limit and to admit air or an inert gas into the equipment so as control the amount of vacuum.
Usage examples of "relief valve".
Following some antique command, the cabin pressure relief valve had opened.
It was only about ten years too late, Kelly estimated, looking up from his notes at the relief valve.
Several times he called Pat to ask for technical information, such as the internal pressure and temperature, whether the cabin relief valve had blown off yet (it hadn't.
Several times he called Pat to ask for technical information, such as the internal pressure and temperature, whether the cabin relief valve had blown off yet (it hadn’.
They should be closing that pressure relief valve, for instance, and setting the floodlights to postlanding, and getting set to cast off the mains after splashdown, so that the Command Module didn't get dragged through the water.
You vented your whole number two tank through the pressure-relief valve.
Justen closed the steam-relief valve and walked around to the driver's seat, where he checked the tiller again to ensure that it moved freely and that the front wheels moved with it.
There was a separate orifice below the mouth: a sphincter muscle that doubled as a pressure-relief valve and whistle.
There was a separate orifice below the mouth: a sphincter muscle that dou- bled as a pressure-relief valve and whistle.
It was a better attempt and although I bounced a couple of feet off the bottom little or no air came out of the relief valve.
Dak said, as I turned the relief valve and air screeched into the tank.
So you're pumping through dead boosters on Eleven and Ten and so on up, and when your overload -- relief valve opens .
No doubt it was a relief valve for her liberal conscience, which must have been having a rough time (which was what it deserved).
Then she cleaned up the wound as best she could, let it air-dry and then taped the latex flap over the wound on three sides, leaving the fourth free as another relief valve.