Ruelco 30C2 Operation Manual

1.0 INTRODUCTION
The Ruelco Model 30C2 (2" NPT
Mount)/31C2 (Flange Mount) 3-way
pneumatic liquid level switch is
typically mounted directly into a tank or
vessel or in an optional external cage
(See Figures 1,2). Horizontal or hang
down displacer elements are available.
This displacer operates a pneumatic
valve when a liquid in a tank or a
pressurized vessel reaches a
predetermined level. The operation
mode, as a high or a low level sensor, is
selected by rotating the valve body 180
degrees.
TYPICAL MOUNTING OF MODEL 30C2
LEVEL SWITCHES
FIG. 2
MODEL 30C2 SHOWN IN
MODEL 3C01 EXTERNAL CAGE
FIG. 1
FLEX LEVEL
LIQUID LEVEL SWITCH
OPERATION MANUAL
OMP# LS-3 – 5/19
2.0 OPERATION (See Fig. 3)
When in the non-tripped condition, the
3-way pneumatic valve is configured as
a normally open valve when set for high
level detection and as a normally closed
valve when set for low level detection.
When used as a high level sensor, the
valve will allow air flow from inlet to
outlet when the liquid is below the
displacer. When liquid contacts the
displacer, the valve will block the inlet
pressure and vent the outlet pressure.
When used as a low level sensor, the
valve will allow air flow from inlet to
outlet when the liquid is above the
displacer. When liquid no longer
contacts the displacer, the valve will
block the inlet pressure and vent the
outlet pressure.
Because of the balanced design of the
valve, variations in instrument pressure
from 5 to 50 PSI will have little effect
on level switch performance.
The switch senses a change in the
buoyancy of a displacer assembly inside
a pressurized or unpressurized vessel.
To transmit the buoyancy change, a
pivoting action is used. The I.D. of the
cone contacts the pivot attached to the
push rod and valve body. The o-ring
(provides a pressure tight seal between
the body and the shaft of the cone
protruding through the o-ring. Pressure
in the vessel, if any, acting on the shaft
of the cone, forces the cone against the
pivot point on the valve body. The
position of this point, at the center of the
o-ring, allows the displacer assembly to
move up or down.
3-WAY