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A shutdown valve (also referred to as SDV or emergency shutdown valve, ESV, ESD, or ESDV; or safety shutoff valve) is an actuated valve designed to stop the flow of a hazardous fluid upon the detection of a dangerous event. This provides protection against possible harm to people, equipment or the environment.
Partial stroke testing (or PST) is a technique used in a control system to allow the user to test a percentage of the possible failure modes of a shut down valve without the need to physically close the valve. PST is used to assist in determining that the safety function will operate on demand.
A depressurization system comprises an actuated valve and a restriction orifice. The BDV valve is normally held in the closed position but opens on demand or on failure of the actuator. A restriction orifice (RO) downstream of the BDV is sized to achieve the desired blowdown rate. A locked-open valve may be located downstream of the orifice.
An isolation valve is a valve in a fluid handling system that stops the flow of process media to a given location, usually for maintenance or safety purposes. [1] They can also be used to provide flow logic (selecting one flow path versus another), and to connect external equipment to a system. [2]
Another reason relates to the hydraulic control line. Hydraulic pressure is required to keep the valve open as part of the failsafe design. However, if the valve is too far down the well, then the weight of the hydraulic fluid alone may apply sufficient pressure to keep the valve open, even with the loss of surface pressurisation.
Turbo-Hydramatic 425 (TH425 or THM 425, [1] later 325) was an automatic transmission developed and produced by General Motors.The THM425 was a derivative of the THM400; most parts directly interchange and some others will interchange with minor modifications.
ElDorado (formerly ElDorado National–Kansas) is an American manufacturer of cutaway buses, owned by Forest River, with its headquarters and main factory in Salina, Kansas. The company was founded in 1960 as Honorbuilt Manufacturing, was acquired by Ohio-based Ward Manufacturing in 1965, was renamed El Dorado R.V. in 1978 and started building ...
In the PORV, the valve is held shut by piping a small amount of the fluid to the rear of the sealing disk, with the pressure balanced on either side. A separate actuator on the piping releases pressure in the line if it crosses a threshold. This releases the pressure on the back of the seal, causing the valve to open.