50-604 Kotron Model 804 Sentinel II RF Level Transmitter
3
Tanks/Silos with Non-Conductive Materials
of Construction
With plastic, concrete, wood, or any other non-conductive
walled vessel, the reference electrode (mentioned in the
Principle of Operation
section on page 1) needs clarifica-
tion. Most commonly, this electrode will be in the form
of a concentric ground tube (for example, a stilling well).
In questionable circumstances, consult the factory. In all
cases, a good electrical connection must be made between
the ground surface and the probe housing.
NOTE: These comments also apply to glass-lined, metal walled tanks.
Caution:
When an insulated probe is used in a hazardous and/or
abrasive medium, the probe should be inspected annually
for nicks, cuts, or abrasions, which may ruin the integrity of
the insulation. In the event that wear is found, replace the
probe or consult the factory for further instructions. This
procedure is critical in vessels containing hazardous media.
2.2
Mounting
Probes should be mounted vertically and such that the
probe rod is at least 2" (50 mm) below the lowest
desired level control point with conductive materials; or,
4" (100 mm) below the lowest desired level control point
in non-conductive materials. Refer to Figure 1.
2.2.1 Mounting Procedure
Kotron Sentinel II Transmitters with standard probes up to
and including 12" (305 mm) in length are shipped pre-
assembled. Units with standard probes over 12" (305 mm)
in length are shipped unassembled to avoid damage during
transit; and must be assembled before mounting. Follow
the proper mounting procedure for specific unit.
NOTE: Before beginning mounting procedures, ensure that the power
source to the unit is off. After installing the probe on the tank,
and before wiring the electronics to the probe, it is beneficial
to perform a probe resistance check to verify the integrity of
the probe.
The resistance of an insulated probe in conductive liquid (or a
bare probe in non-conductive media), when measured
between the probe screw terminal and the probe mounting
nut with an ohmmeter set to its 20 megohm scale, should
be INFINITE.
2.2.2 Integral Mount with Standard Rigid Probe
1. Thread probe into mounting bushing on tank.
2. Tighten securely—being certain that the wrench is applied
only to the lower probe nut.
Figure 1
Mounting nut
Tank
mounting
bushing
Actuation
point in
conductive
media
2"
