IS220PSVOH1A facilitates a comprehensive review and dialogue on the causes and effects of bypassing a particular tool. It facilitates a review of the situation and the choices made, while assessing the feasibility of bypassing the tool and enumerating the steps to be taken thereafter. The beta factor used to estimate the percentage of common cause failures under different conditions using the methodology described in the ISA 84.01 TR2 technical document.

IS220PSVOH1A Objectives of a performance-oriented fire and gas study, methods used to assess the efficiency of a customer’s fire and gas system, and tools and calculations needed to identify fire and gas coverage areas. The worksheet calculates the failure rate of a component, allowing the user to configure the confidence level, e.g. 70% as recommended by the IEC 61508 standard. A structured format is provided for performing straightforward failure mode, impact and diagnostic assessments.

IS220PSVOH1A is particularly useful for assessing the global failure characteristics of systems with multiple components, such as dual transmitters for differential pressure calculations, or installations involving solenoids, actuators and valves with partial stroke tests. Typically, failure statistics from suppliers are categorised into high, low and hazardous failure types (detected or not detected).