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 Capacitance
often referred to RF (radio frequency) technology uses the electrical
characteristics of a capacitor to detect or measure the level
of liquids, slurries, granular's or interfaces contained in a
vessel. A jacketed or bare conductive sensing electrode (probe)
is inserted into the tank to act as one conductor of the capacitor.
The metal wall of the tank acts as the other. For nonmetallic
and plastic tanks, capacitance probes with a dual probe system
exists where the second probe is used as the other capacitor conductor.
The capacitance level sensor measures the change in capacitance
that occurs when the tank level changes and the tank contents
rise or descend along the sensing probe. This capacitance is measured
to provide a direct linear measurement of tank level or a switch
contact.
Capacitance Technology Advantages:
- Can
operate under extreme temperature and pressure
- By
far the most versatile technology
- Works
with all types of materials
- On-off
or continuous measurement
- Typically
inexpensive.
Capacitance Technology Disadvantages:
- Intrusive
measurement
- Errors
due to buildup and varying dielectric strength
- Application
Sensitive
- Insulating
granular measurements require special considerations
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