Xylem SDI-12 RADAR - Manual (Page 10)

iNSTaLLaTioN & maiNTeNaNCe
8
General installation recommendations
Before proceeding with the installation, please consider several site preparation and maintenance
issues. The radar Series has been designed to operate safely in accordance with current technical,
safety and eU standards. Personnel must be authorised and suitably qualified. The manual must
have been read and understood, and the instructions followed.
Warning: working over water or on tall structures can be dangerous. Use a safety harness,
fall arrest device, life saver and/or other safety equipment when conditions warrant.
Follow these guidelines when selecting a location for the radar gauge:
• The radar unit is a precision instrument and should not be jarred or dropped.
• The sensor must be mounted rigidly to prevent movement from wind and vibration.
• The antenna horn must be aligned within 1 ° of vertical to prevent trigonometric measurement errors.
• Make certain the sensor is mounted high enough to avoid being submerged during high water or flood
conditions.
• The sensor is rated NEMA 4x and can be mounted outdoors in unprotected locations.
• The operating temperature range for the sensor is –40 ° C to 80 ° C.
• The sensor should be mounted above the smoothest portion of the water surface. Generally between piers
of a bridge structure. However on bridges with long spans between the piers there will be more vibration
on the bridge. To moderate the vibration in these situations mount the radar 1/4 to 1/3 the span distance
from the pier.
• There should be a clear path between the sensor and the water to avoid false reflections. Try to locate the
sensor to keep the beam path (8 ° for 4-inch horn, 10 ° for 3-inch horn) clear of excessive turbulence,
splashing, waves, pipes, wires and other obstructions.
• Avoid submerged obstructions such as rocks or bridge piers that disturb or distort the water level.
• The mounting location should also avoid horizontal structural surfaces such as beams, brackets, and side
wall joints because these surfaces tend to reflect a strong false signal. if these cannot be avoided the display
can be used to map the radar beam profile and optimize the profile by means of electronic suppression of
interference echoes.
• Be aware that bridges and other large structures expand and contract with temperature. The bridge height
can change a few inches with diurnal temperature changes. Trucks and other traffic loads can cause transient
changes to the bridge height.
mounting the radar Unit - Vertical alignment
Make certain the horn antenna is aligned within 1 ° of vertical. If the antenna is not vertical a
trigonometric measurement error with respect to the water will occur and the maximum range will
be reduced due to the off-axis return signal.