Definitions

Voting is related to the architecture of a system (1oo2, 2oo2, 2oo3, and so on). It can be defined as the minimum number of “paths” that should work out of the total number of paths available within the architecture. For example, a 1oo2 architecture requires at least one path to work, where a 2oo4 architecture …

Velocity/speed sensors are used for low to medium frequency vibration measurements.

Velocity / velocity, is a parameter used to measure mechanical vibration. Velocity / speed is the degree to which displacement changes with time.

Occurs when the rotor rotates downward until the heaviest point hangs straight down.

The Safety Integrity Level (SIL) is a measure of performance required for a Safety Instrumented Function (SIF). SIL is a component of Functional Safety and is used to quantify the risk reductions of a monitoring system using four levels (SIL 1, SIL 2, SIL 3 and SIL 4).

A system used to monitor the condition of certain values and parameters of a machine by using pre-set operational limits that, when exceeded, trigger an alarm that causes the respective machine to trip (shut down).

A specific function provided by the Safety Instrumented System (SIS) with the purpose of reducing the risk of a specific hazard. The function can serve to bring an industrial process to a safe state when certain conditions (parameters) are violated or to reduce the consequences of certain hazardous events.

Safe Failure Fraction (SFF) is the ratio of total potential failures to dangerous undetected failures.

A risk graph is a simplified, quantitative, method of risk assessment used for screening Safety Instrumented Functions (SIF). A risk graph often has an exploratory function prior to the more comprehensive Layer of Protection Analysis (LOPA). However, a risk graph can also be used as a stand-alone method of risk assessment.

The Layer of Protection Analysis (LOPA) is a simplified form of risk assessment what is often used to classify the Safety Integrity Level (SIL). An LOPA assesses whether the current Independent Protection Layer(s) (IPL), or layers of protection, are sufficient to protect against a specific hazardous situation.