1.0
Reference Information
1.1
Principle of Operation
Figures 1 & 2 illustrate the simple, reliable operating prin-
ciple of a float level switch. Switching action is obtained
through the use of a magnetic sleeve
➃
and a float
➂
,
displacer or flow sensing element and a switching mecha-
nism
➁
. These two basic component assemblies are sepa-
rated by a non-magnetic, pressure tight enclosing tube
➄
.
The switch
➁
and magnet
➀
are assembled to a mecha-
nism with a swinging arm which operates on precision
stainless steel pivots.
1.2
Operating Cycle
As level of a liquid in a vessel rises (Figure 1), the float
rides on the liquid surface moving the magnetic sleeve
upward in the enclosing tube and into the field of the
switch mechanism magnet. As a result, the magnet is
drawn in tightly to the enclosing tube causing the set
screw on the swinging arm to move the actuating lever of a
snap action switch, making or breaking the electrical cir-
cuit. As the liquid level recedes (Figure 2), the float and
magnetic sleeve moves downward until the switch magnet
releases and is drawn outward, away from the enclosing
tube by a tension spring. This in turn moves the actuating
arm of the switch in the opposite direction, thus reversing
switch action.
Switch mechanisms may include a single switch or multi-
ple switches, depending on operational requirements and
switching action desired.
1
42-799 Series ‘R’ Electric Switch Mechanisms
Pivot
4
3
5
2
1
Figure 1
Rising Level
Figure 2
Falling Level
