Magnetic Bond Method
Figure 7 Magnetic Bond Detector
The magnetic bond method was developed to
overcome the problems of cages and stuffing
boxes. The magnetic bond mechanism consists of
a magnetic float which rises and falls with
changes in level. The float travels outside of a
non-magnetic tube which houses an inner magnet
connected to a level indicator. When the float
rises and falls, the outer magnet will attract the
inner magnet, causing the inner magnet to follow
the level within the vessel (Figure 7).
Conductivity Probe Method
Figure 8 illustrates a conductivity probe level
detection system. It consists of one or more level
detectors, an operating relay, and a controller.
When the liquid makes contact with any of the
electrodes, an electric current will flow between the electrode and ground. The current energizes
a relay which causes the relay contacts to open or close depending on the state of the process
involved. The relay in turn will actuate an alarm, a pump, a control valve, or all three. A typical
system has three probes: a low level probe, a high level probe, and a high level alarm probe.
Figure 8 Conductivity Probe Level Detection System