Section 4 Service, Configuration & Testing
17
FT742-SM (RS422 & RS485) Sensors
– User Manual
4 SERVICE, CONFIGURATION & TESTING
4.1 Inspection
The following checks are required to identify any signs of corrosion or damage on the sensor which may hinder
its performance. It is recommended that these checks be carried out annually.
Mechanical damage:
Check the sensor body for signs of damage, paying particular attention to the seals. Also
inspect for signs of lightning damage which may appear as burns or scorch marks (or burnt smells). If damage
has occurred replace the sensor immediately. Inspect the hydrophobic cavity coating for wear, corrosion and
damage. Check the O-ring seal and fixings are in good condition, replace them if necessary for long-term
protection.
Corrosion:
Inspect the mounting surfaces of the sensor for signs of corrosion. If corrosion is present on any
surface, it should be removed using an abrasive cloth. Before reinstalling the sensor, electrical joint compound
should be
applied to the sensor’s mounting flat (see Section 3). Check that any fixings and O-rings are in good
condition with no signs of corrosion and tighten as necessary. If corrosion is present replace with parts of the
appropriate finish (see Section 3).
Interconnection cable:
Inspect the condition of the cable. If it has become frayed or damaged it should be
replaced. Intermittent cable faults may not be visible and may show up as data errors. Check the intended
network component values (termination resistors etc.).
Connector protective sleeve:
If cable protection is used, check for any signs of damage or degradation.
Cleaning:
The measurement cavity has a special hydrophobic coating (water repelling) which helps to prevent
water building up. When water enters the measurement cavity the surface helps to wash away dust and debris
which may have settled. If any debris is present this can be removed by gently rinsing the measurement cavity
surface with distilled water using a laboratory wash bottle or similar. Please note excess water droplets can be
removed by lightly blowing or shaking the sensor.
