Model 765
EXTERNAL CAGE LEVEL SWITCH
Download
the Series 700 Detailed Datasheet in Acrobat Format
- Operation: A
float with a long stroke action moves up and down as the liquid level varies.
Switching occurs at up to four separate points. - Switching Stations: 1 to 4; alarm and/or differential
- Differential: up to 72"
- Specific Gravity: 0.4 to 2.4
- Temperature: -20 to 750°F
- Pressure: -15 to 2200 PSIG
- Process Connection: Same as type 760
Model 765A External Cage Level Switch
Vertically Rising Float, Two Alarm Points
OPERATIONThe Delta Controls Model 765A provides output alarm switching at two elevations of a varying liquid level. The unit has its float mounted outside the process vessel in a cage. The external cage design is utilized to minimize process turbulence effects and in order that the level control may be valved off from the process vessel and depressurized for maintenance without disturbing the operation of the process. The barrier tube isolates the process liquid from the switch stations. The output consists of switching action as the liquid level varies. Two switch stations are operated.
Each is equipped with a magnet whose lines of force pass through the nonmagnetic barrier tube. Action occurs as the attractor is lifted up into the magnetic field of a switching station. The magnet is pulled in against the outside of the barrier tube when the attractor is lifted into the magnetic field inside the tube.
The liquid level rises and the float lifts the attractor in front of the bottom switch station magnet; its magnet pulls in and the output switch is actuated.
An additional increase in liquid level of approximately 2 inches lifts the attractor up into the field of the top switch station magnet and its output switch is actuated. Decreasing liquid level moves the float/rod/collars downwards. The output switch deactuates when the attractor is pulled out of the magnetic field.
INSTALLATION
The Delta Controls Model 765A should be mounted vertically near the process vessel containing the liquid level to be monitored. It should be positioned so that the desired switching points are located at the desired liquid level elevations and they must be between the upper and lower process vessel connections on the element body. Long lines connecting the process vessel to the element chamber should be avoided; but when necessary, they should be sloped 1" per foot towards the process vessel too limit sedimentation buildup.
Model
765D External Cage Level Switch
Vertically Rising Float, One On/Off Differential Point
OPERATION
The Delta Controls Model 765D provides switching at two elevations of a varying liquid level. The unit has its float mounted outside the process vessel in a cage. The external cage design is utilized to minimize process turbulence effects and in order that the level control may be valved off from the process vessel and depressurized for maintenance without disturbing the operation of the process. The output of the control consists of and on/off switching action as the liquid level varies. The differential level change required to change the output switch from one condition to the other may be increased up to about 2 inches.
The barrier tube isolates the process liquid from the switch station. The switch station is on the outside of the barrier tube. It is equipped with a magnet whose lines of force pass through the nonmagnetic barrier tube. The magnet is pulled in against the outside of the tube when the attractor is lifted into the magnetic field inside the tube.
DIFFERENTIAL ACTION
The liquid level rises and the float lifts the attractor in front of the switch station magnet. The magnet pulls in, the output switch is actuated, and the attractor is "captured" and held in place.
Decreasing liquid level moves the float/rod/collars downward. The output switch remains actuated until the top collar moves down against the attractor and pulls it out of the magnetic field. The attractor then falls down against the lower collar by gravity and the output switch is deactuated.
The spacing between the top collar, at its maximum elevation, and the attractor determines the amount of liquid level differential between output switch actuation and deactuation. Lowering the top collar decreases differential. Access to the collars is achieved by depressurizing the unit and removing the barrier tube.
INSTALLATION
The Delta Controls Model 765D should be mounted vertically near the process vessel containing the liquid level to be monitored. Long lines connecting the process vessel to the element chamber should be avoided; but when necessary, they should be sloped 1" per foot towards the process vessel to limit sedimentation buildup.
