MSA Senscient ELDS 1000 series, Руководство по эксплуатации

Страница: 40 / 184

Installation Design & Engineering
40
Senscient ELDS™
Rev 15
GB
When the installation designer takes the above factors into account, in general they will establish
that the best locations for Cross Duct gas detectors are as follows:
1. As close to the duct inlet as reasonably practicable - to minimize the distance that any
flammable gas has to cover before it passes through the Cross Duct detector’s beam-path,
minimizing any time delay before this hazardous condition is detected.
2. For tall ducts – at multiple heights running across the width of the duct, with as a minimum one
Cross Duct beam-path running reasonably close to the bottom of the duct and another Cross
Duct beam-path running reasonably close to the top of the duct.
3. For tall / large ducts where practicable – at multiple heights running across the width of the
duct with Cross Duct beam-paths separated vertically by a 0.4m pitch.
CAUTION
Do NOT install Cross Duct ELDS units with their beam-paths running vertically in the duct. This
will tend to lead to the build-up of water and contamination upon the lens-window of the unit
mounted on the bottom of the duct, leading to low signal and beam-blockage problems.
The installation Design Authority must ensure that the duct hazardous (classified) location
and / or hazardous area is in compliance with the ELDS unit’s certification (see section 9
for ELDS certification details).
In addition, the duct environment shall not exceed the following:
Pressure: 80kPa (0.8Bar) to 110kPa (1.1Bar)
Temperature: -55ºC to +60ºC
Oxygen Content: less than 21%v/v.
3.2.10 Siting Multiple ELDS™ Systems
For reliable operation it is important that each ELDS™ Receiver unit only detects light from a
single ELDS™ Transmitter, i.e. that ELDS™ systems are installed as a Transmitter and Receiver
pair that are optically isolated from other ELDS™ systems.
In situations where multiple ELDS™ are to be installed in proximity to each other along a common
border or fence line, the following mounting and orientation recommendations should be adopted.
Arrangement for 2 ELDS™ Systems
Where two ELDS™ systems are to be installed along a common border or fence line, it is
recommended that the units be orientated as illustrated below.
Mounting the transmitters and receivers such that the beams of the two ELDS™ systems are
running in opposite directions ensures complete optical isolation. In this arrangement for two
ELDS™ systems it is not necessary to make use of the heights or pole sides upon which the units
are mounted to provide optical isolation.
Tx 1
Tx 2
Rx 1
Rx 2