MSA Senscient ELDS 1000 series, Operating Manual

Page: 79 / 184

Installation & Commissioning
Senscient ELDS™
Rev 15 79
GB
4.4. Cross Duct – Alignment Requirements
The majority of Cross Duct ELDS systems are designed to be installed and ‘aligned’ by simply
mounting each half of the system opposite its counterpart on the other side of the duct. Provided
that the duct walls are nominally parallel and sufficiently rigid that they do not deform significantly
when the Cross Duct ELDS system is mounted upon them, no alignment is required.
In order to enable this simplified installation process, the Transmitter and Receiver units of a Cross
Duct ELDS system have a wide field-of-view (≥ 6°), enabling these units to tolerate out-of-parallel
angular errors up to ±2.5° on each side of the duct wall. All that is then necessary is that the
optical centre-lines of each half of the system should be opposite each other to within ±25mm
when mounted on the duct wall. This modest requirement can be met by employing normal
constructional methods and tools, such that the cross-hairs on the Mounting Plate templates are
positioned opposite each other when they are used to guide the drilling and cutting of the required
mounting holes.
4.4.1 Cross Duct Alignment Adjustment Bushings
For installations on narrow ducts with rigid walls, Cross Duct ELDS systems can be successfully
installed and commissioned by taking advantage of the simplified, no-alignment-required process
that is made possible by the intentionally wide field-of-view of these systems.
However, in some instances, especially those involving retrofit of ELDS units on pre-existing
installations, or on thin-walled ducts, it is possible that the mounts or duct walls will be so far out-
of-parallel that the relative alignment of the RX and TX units will fall outside of the angular
alignment tolerance of Cross Duct ELDS systems (±2.5° per side). In order to enable Cross Duct
ELDS systems to be successfully installed on out-of-parallel mounts or ducts, Senscient provides
alignment adjustment bushings.
The alignment adjustment bushings are fitted between the ELDS TX or RX units and the mounting
plate, providing a compressible alignment adjustment interface. The alignment adjustment
bushings are made from a solid elastomer, chosen for excellent resistance to compression-set and
suitability for long term use at industrial facilities. The alignment adjustment bushings provide at
least ±5° angular adjustment in the horizontal and vertical planes for both the TX and RX units,
enabling even significant out-of-parallel errors to be accommodated.