Diagnosing Slg720 Coaxial Probe Misassembly - Honeywell SmartLine SLG 700 User Manual

6.2 Diagnosing SLG720 Coaxial Probe misassembly

There have been a number of instances of SLG720 coaxial probes being misassembled in the field.
This document is intended to help diagnose these issues; hopefully, before transmitter installation.
Issues:
1. Spacer movement: if sufficient care has not been applied during assembly, the spacers,
normally in place every meter, can move from the lock washers on which they are placed.
Often these lock-washers can push the central conductor against the inside of the tube. This
will result in false levels being detected where the central conductor touches the outer tube.
2. Nut placement: if the nut locking the central conductor to the process connector is missing or
misassembled, it can cause false tank full alarms.
3. Bent probe
Mechanical Inspection:
1. The central conductor should be close to the center of the tube for its entire length. Especially
close to the PTFE spacers which are placed every meter. If the probe is placed horizontally so
that the holes are also horizontal, it should not be possible to see more than a little bit
between the two opposing holes.
Spacer is missing – can see between opposing
holes in coaxial tube
Revision 8
SLG 700 SmartLine Level Transmitter User's Manual
Spacer is in place – can only see a minimal
amount between opposing holes.
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