MANUAL # OMP L80‐P REV. 6
INTRODUCTION
The K‐Dyne, Inc. electric version of the Model L80 is a 2" NPT mounted liquid level switch. It is typically
mounted in a K‐Dyne Model C80 cage shown in the figure 1 for external bridle mounting or may be
internally mounted in a 2" NPT (F) connection. Both mounting configurations are shown in figure 2.
assembly (9) inside either a pressurized or an unpressurized vessel. A pivoting action is used to transmit
the buoyancy change of the displacer assembly. The bore of the cone (14) contacts a pivot (13) on the
pivot body (3). The o‐ring (8) provides a pressure tight seal between he body (7) and the shaft of the
cone protruding through the o‐ring.
Pressure in the vessel acting on the shaft of the cone forces the cone against the pivot. The position of
the pivot point, at the center of the o‐ring, allows the displacer assembly to move vertically with the
liquid level. This motion is guided to act along the axis of the transverse rod (16) by two vertical tabs on
the pivot body that mate with notches in the cone. Any vertical motion of the displacer is transmitted by
the cone to the ends of the transverse rod. A ramp on the outside diameter of the transverse rod
contacts the tip of the push rod (17) to operate the lever on the switch assembly (2).
2.1 LOW OPERATION
For use as a low‐level sensor (output on rising level), the pivot body (13) is positioned with the enlarge
end of the transverse rod (16) up towards the spring cap (4). The displacer assembly weight exerts a
clockwise rotational force on the cone through the pivot. The spring (5), acting through he spring guide
(6) exerts a counterclockwise rotational force on the cone. When the liquid level is below the displacer
assembly, the clockwise force is greater. This force causes the cone to push upward against the
transverse rod allowing the tip of the push rod to be positioned away from the switch assembly lever. In
These sensors send or remove an electric signal when a liquid in
a tank or a pressurized vessel reaches a predetermined level. The
L80 operation mode as either a low (direct) or high (reverse)
acting level switch is selected by rotating the pivot body 180˚.
Selection of N.O. or N.C. switching depends upon the wiring
configuration utilized. Both SPDT or DPDT snap acting dry
contacts offered with the switch are U.L.T rated for hazardous
locations.
2.0 PRINCIPLE OF OPERATION (Refer to Figure 3)
The electric version of the K‐Dyne, Inc. Model L80 2" NPT
mounted liquid level switch is a multi‐functional pneumatic liquid
level sensor. Depending on the mode of operation, it functions
as a three way, normal closed (N.C.) or normally open (N..O.)
electric switch that will operate when the liquid level rises or falls
below a fixed point in a tank or pressurize vessel. Type of voltage
may be A.C. or D. C. and the maximum amperage depends on the
amount of voltage used. Consult the data sheet of the specific
switch being used for the switch rating.
The switch senses a change in the buoyancy of a displacer