保护层LOPA试题.ppt

* Some mitigation systems can be considered for Environmental cases.However each company needs to decide its stance on mitigation versus prevention. For example, the PFD of a fire protection system may not be known and almost never tested in ‘anger’. * * So what properties does SIS have? * With IPLs , if Safety Instrumented Systems are needed to close the protection gap, they would normally be considered last (because they bring new requirements such as ‘rules’ going much further than selection of the system).We shall review typical rules here and later. * With IPLs , if Safety Instrumented Systems are needed to close the protection gap, they would normally be considered last (because they bring new requirements such as ‘rules’ going much further than selection of the system).We shall review typical rules here and later. * * It is important to understand the differences between BPCS and SIS.IEC 61511 has guidance which amplifies this. * We now arrive at the SIL of the SIS.(if one or more are needed) * Documentation for each case and IPLs is required. Examples are provided in the course material. * When a SIS is shown to be needed, it will need to have Safety Integrity Level (SIL) 1, 2 or 3.Depending on the integer in the Protection Gap column of the worksheet. Any SIS needed must be installed with the correct configuration……. * Layer of Protection Analysis is not the only acceptable way to implement Safety Instrumented Systems. There are more Qualitative’ approaches which can be used. * * * In the U.K. the Health and Safety Executive applies a principle called ALARP.As Low as Reasonably Practicable.It is intended to assist stakeholders to be sure that ‘sufficient’ action is taken to reduce risks. * Risks falling into the unacceptable region will not be tolerated - whatever apparent benefits accrue. Risks falling into the Broadly Acceptable region are generally regarded as insignificant and adequately controlled.No further action seems to be required unless