Search
Glossary Term: Burn-in
Device operation, usually under accelerated environmental conditions that simulate life in the devices’ intended application, used to detect early-life (infant mortality) failures. Such testing helps to ensure that constant failure rate assumptions for equipment are valid and do not lead to accidents during plant start up.
Glossary Term: BPCS
See Basic Process Control System.
Glossary Term: BMS
Burner management system. The control system designed to improve combustion safety and assist the operator in starting and stopping the burners. It also should prevent mis-operation and damage to the fuel preparation and burning equipment. The BMS can include: interlock system, fuel trip system, master fuel trip system, master fuel…
Glossary Term: BLEVE
Boiling liquid expanding vapor explosion. A specific type of fireball that can occur as the result of the situation where a vessel containing a pressurized liquid comes in direct contact with external flame. As the liquid inside the vessel absorbs the heat of the external fire, the liquid begins to…
Glossary Term: β-factor
Beta factor, indicating common cause susceptibility. The fraction of total failure rate that is attributed to a single cause in common with other units in the group. A common cause failure will result in all units with the group failing simultaneously.
Glossary Term: Batch process
A process that manufactures a fixed quantity of material by subjecting measured quantities of raw materials to a time sequential order of processing actions using one or more pieces of equipment. Typically used for small volume production of high value materials.
Glossary Term: Basic process control system
System which responds to input signals from the process, associated equipment, and/or an operator and generates output signals causing the process and its associated equipment to operate in the desired way. The BPCS can not perform any safety instrumented functions rated with a safety integrity level of 1 or better…
Glossary Term: Availability
The probability that a device is operating successfully at a given moment in time. This is a measure of the “uptime” and is defined in units of percent. For most tested and repaired safety system components, the availability varies as a saw tooth with time as governed by the proof…
Glossary Term: Auto-tuning
Controller feature that calculates proportional, integral and derivative (PID) output settings based on calculations using measured process dynamics and combining those with the parameters of a PID controller. Calculations may be based on transient responses, frequency responses or parametric models.
Glossary Term: Asynchronous communication
Circuitry or operation without common clock or timing signals. Often called start/stop transmission; a way of transmitting data in which each character is preceded by a start bit and followed by a stop bit.
Glossary Term: As-built
A document revision that includes all modifications performed as a result of actual fabrication or installation. Note for safety systems, that where the actual installation does not conform to the design information, then the difference shall be evaluated and the likely impact on safety determined. If the difference has no…
Glossary Term: Architectural constraints or AC
Limitations that are imposed on the hardware selected to implement a safety-instrumented function, regardless of the performance calculated for a subsystem. Architectural constraints are specified (in IEC 61508-2-Table 2 and IEC 61511-Table 5) according to the required SIL of the subsystem, type of components used, and SFF of the subsystem’s…
Glossary Term: Architecture
The voting structure of different elements in a safety instrumented function. See Architectural Constraints, Fault Tolerance and 2oo3.
Glossary Term: Annunciator
A device or group of devices that call attention to changes in process conditions that have occurred. Usually included are sequence logic circuits, labeled visual displays, audible devices, and manually operated acknowledge and reset push buttons.
Glossary Term: Analogue I/O
Input or output signals to or from the filed that vary continuously over a range of values. Typically voltage, electric current, temperature, or pressure signals are analogue.
Glossary Term: Algorithm
A prescribed set of well defined rules or processes for the solution of a problem in a finite number of steps.
Glossary Term: ALARP
As low as reasonably practicable. The philosophy of dealing with risks that fall between an upper and lower extreme. The upper extreme is where the risk is so great that it is rejected completely while the lower extreme is where the risk is, or has been made to be, insignificant.…
Glossary Term: Actuator
A device responsible for putting a mechanical device into action such as a valve. Single acting actuators act in only one direction such as in a spring and diaphragm actuator where the spring acts in a direction opposite to the diaphragm thrust. Double acting actuators have a power supply that…
Glossary Term: IEC 61511
The IEC standard for use of electrical / electronic / programmable electronic safety-related systems in the process industry. Like IEC 61508 it focuses on a set of safety lifecycle processes to manage process risk. It was originally published by the IEC in 2003 and taken up by the US in…
Glossary Term: IEC 61508
The IEC standard covering Functional Safety of electrical / electronic / programmable electronic safety-related systems. The main objective of IEC61508 is to use safety instrumented systems reduce risk to a tolerable level by following the overall, hardware and software safety lifecycle procedures and by maintaining the associated documentation. Issued in…
Page 120 of 146 pages. ‹ First < 118 119 120 121 122 > Last ›