6
46-622 Series 3 Liquid Level Switches ASME B31.3 Construction
Controls should be mounted as close to the vessel as possible.
This will result in a more responsive and accurate level
change in the control. Liquid in a long line may be cooler
and more dense than liquid in the vessel causing lower level
indication in the control than actual level in the vessel.
Caution:
Operation of all buoyancy type level devices should be
done in such a way as to minimize the action of dynamic
forces on the float or displacer sensing element. Good
practice for reducing the likelihood of damage to the con-
trol is to equalize pressure across the device slowly.
2.5
Wiring
NOTE: A switch or circuit breaker shall be installed in close proximity
to equipment and within easy reach of operator. It shall be
marked as the disconnecting device for the equipment.
NOTE: For supply connections in installations with ambient tempera-
ture up to +158 °F (+70 °C), use wire with a minimum rating of
+167 °F (+75 °C) as required by the process conditions.
Installations with ambient temperatures up to +176 °F (+80 °C)
require wire with a minimum rating of +185 °F (+85 °C) as
required by the process conditions. Use a minimum of
14 AWG wire for power and ground field wires.
Caution:
Level controls are shipped from the factory with the
enclosing tube tightened and the middle set screw, on the
housing base, locked to the enclosing tube. Failure to
loosen the set screw prior to repositioning the conduit
connection may cause the enclosing tube to loosen,
resulting in the possible leakage of the process liquid
or vapor.
Series 3 controls are shipped with the conduit entry of
the switch housing placed 180° opposite to the tank con-
figurations to simplify installation in most cases. If this
configuration is appropriate to the installation, proceed to
step 4 to begin wiring the unit. If another configuration is
desired, the switch housing can be easily rotated by first
following steps 1, 2, and 3.
1. Loosen set screw(s) at base of switch housing. Refer to
Figure 4
.
2. Switch housing may be rotated 360° to allow correct posi-
tioning of conduit outlet.
3. Tighten set screw(s) at base of switch housing.
4. Unscrew and remove switch housing cover. The threads
have been lubricated to facilitate removal.
NOTE: On high temperature applications (above +250 °F [+121 °C] in
float chamber), high temperature wire should be used
between control and first junction box located in a cooler area.
On non-hazardous applications, flexible conduit may be used
between the control and the first junction box.
Internal Circuit
(Right) Switch
1
2
3
Load
Load
Close on high level
Common
Close on low level
Line
4
5
6
Internal Circuit
(Left) Switch
Load
Load
Close on high level
Common
Close on low level
Line
Set
Screw
Screw
Screw
Figure 4
NEMA 4X/7/9
Figure 5
Wiring diagram for DPDT
Series B, C, D, F, R, 8 & 9 switches
