Emergency Isolation Valves EIV

Emergency isolation valves (EIV) should be located based one two principals (1) the amount of isolatable inventory that is desired and (2) protection of the EIV from the affects of external events. EIV valves are normally required to have a firesafe rating (i.e. minimal leakage and operability capability, Ref. Table 14). Valves and their actuating mechanisms should be afforded adequate protection when they are required to be located in an area that has potential to experience explosion and fire incidents. 

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Employers need to decide what type of release their own employees can reasonably be expected to handle. For small releases, the best action to take is often to find the isolation valves on either side of the release and to close them. For a major incident, operators need to close the unit Emergency Isolation Valves (EIVs). There is a balance here on the one hand, having a person move into a situation to close the valves puts him at risk. On the other hand, if he does not take prompt action, the small release may become bigger and could lead to many more... 

Emergency Isolation Valve (EIV) a wJve that, in event of fire, rupture, or loss of containment, is used to stop the release of flammable or combustible liquids, combustible gas, or potentially toxic material. An EIV can be either hand-operated or power-operated... 

If there is a serious fire on a unit, it may be impossible for the operators to reach the valves that must be closed to stop additional flammable material from feeding the fire. Therefore, it is useful to have emergency isolation valves (EIVs) at the unit s perimeter. If these valves are closed, the flow of all hazardous chemicals into the unit will be stopped and the fire will go out once the inventory of material within the unit has been consumed. The EIVs must be located and protected such that they are not damaged in a fire or explosion, and operators can reach them in an emergency. EIVs can be either manual or automatic. If they are... 

For BSD emergency isolation valves (i.e., EIVs), a fail safe mode is normally defined as fail close in order to prevent the continued flow of fuel to an incident. Blowdown or depressurization valves would be specified as fail open to allow inventories to be disposed of during an incident. Special circumstances may require the use of a fail steady valve for operational or specialized purposes. These specialized applications are usually at isolation valves for individual components such as vessels, pumps, compressors, etc., where a backup BIV is also provided at the battery limits of the plant that is specified as fail close. The fail safe mode can be defined as the action that is taken when the BSD system is activated. Since the function of the BSD system is to place the facility in its safest mode, by definition, the BSD activation mode is the fail safe mode. 

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