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Control and Instrumentation Glossary

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LAN - Local Area Network
A data communications network which is geographically limited (typically to a 1 km radius) allowing easy interconnection of devices.
Ethernet is an example of a standard LAN.
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French based Notified Body

Further Reading


Light Emitting Diode

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LEL - Lower Explosive Limit
Below the LEL a mixture of substance and air lacks sufficient fuel (substance) to burn.

Further Reading


Local Equipment Room

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Lower Flamability Limit
Below the LFL a mixture of substance and air lacks sufficient fuel (substance) to burn.
Further Reading


The closeness to which a curve approximates a straight line or the deviation of an instrument's response from a straight line.

Further Reading


LNG - Liquefied Natural Gas
Natural gas (mainly methane) refrigerated to reach liquid phase suitable for transportation in specialised vessels or by pipeline.

Further Reading


Spanish based Notified Body

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LOPA - Layers of Protection Analysis
A semi-quantitative risk analysis technique.
LOPA results are intended to be conservative (overestimating the risk) and usually adequate to understand the required safety integrity level.
Further Reading
SIL Ratings Toolbox Page

Line of Sight
Typically used with reference to telecommunication devices.
Further Reading


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