Model 767A

SKU: 767A

Displacer Switch, External Cage, Vertical, Two Point, Optional Differential, Wide Spacing

  • 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

Operation

The Delta Controls Model 767A provides switching action at two field selected liquid level elevations. The unit has its element mounted outside the process vessel. The external cage design, with flanged cage closure, 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 setpoint adjustment or maintenance without disturbing the operation of the process. Two switch stations are operated as the liquid level varies. Action occurs as the attractor moves in front of each switching station magnet. The barrier tube isolates the switch stations from the process liquid.

Installation

The Delta Controls Model 767A should be mounted vertically near the process vessel containing the liquid level to be monitored. It should be positioned so that the desired switching point is located between the upper and lower process 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 to limit sedimentation buildup. The process isolation valves and drain system should be in accordance with the governing codes. The Model 767A can be quite heavy. Suitable additional supports should be provided when needed.

Setpoint Collar Adjustment

The setpoint collar is locked in place by a socket head setscrew. The collars may be repositioned as required to achieve switching action at various fluid elevations.

Sliding Float

The spring supports the weight of the attractor/stroke rod assembly in the middle, or neutral position. The position of the spring collar is adjusted so that the attractor is positioned in the center of its travel when the float is floating on the liquid surface and is not in contact with either setpoint collar.

Sliding Float

The float has a hollow tube through its centerline. The tube is generously larger than the stroke rod which passes through the tube and maintains the float's horizontal position. The float is normally supported by the liquid and moves up and down on the stroke rod as the liquid level varies. An "upper" and a "lower" setpoint collar are positioned on the stroke rod. The float pushes against one of the collars when the fluid level rises or falls to that setpoint elevation. The force produced by the float moves the stroke rod and positions the attractor in front of a switch station magnet. The magnet is attracted and that output signal switch is operated.

Alarm Action

Two independent switch stations are mounted on the barrier tube. On/Off switch action occurs as the float contacts the upper or lower collars and moves the attractor in front of the switch station magnet.

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