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MAN0530 Issue 09 October 03
Searchline Excel
2104M0506
B.1 TERMINOLOGY
Ex d
Flame proof or explosion proof within the confines of European standards EN50014 and
EN50018. An enclosure that can withstand the pressure developed during the internal explosion
of an explosive mixture and that prevents transmission of the explosion to the explosive
atmosphere surrounding the enclosure.
Ex e
Increased safety within the confines of European standards EN50014 and EN50019 applied to
electrical apparatus that does not produce arcs or sparks in normal service, in which additional
measures are applied so as to give increased security against the possibility of excessive
temperatures.
Instrument Assisted Alignment (IAA)
A method of commissioning the Excel system using the associated electronic Handheld
Interrogator device. The process will not allow the Excel system to initialise unless the alignment
of the Receiver and Transmitter is correct and the signal strength is correct.
IS
Intrinsically safe, apparatus in which the circuits themselves are incapable of causing ignition of
a flammable gas.
Lower Explosive Limit (LEL)
The volume of flammable gas or vapour in air below which an explosive gas atmosphere will
not be formed.
RS485
An industry-wide serial communication link protocol.
Turbo heating
Increased Transmitter window heating at low operating temperatures.
B.2 MEASUREMENT UNITS
LEL.m
Lower Explosive Limit metres. Open path detectors measure the amount of gas present in the
beam. However, they cannot discriminate between a low concentration gas cloud over a large
area and a high concentration gas cloud in a small area. % LEL has little meaning in this
situation and so gas readings of LEL.m are used. LEL.m is calculated by multiplying the size of
a gas cloud by its concentration.
APPENDIX B - GLOSSARY
