Model 763Y

SKU: 763Y

Displacer Switch, External Cage, Horizontal, High Temperature and Pressure, Steam Service

The Delta Controls Model 763 is specially intended for the really tough applications found in boiler houses and heating facilities. Typical uses include steam drum level and drip leg services. Various element styles are utilized so as to produce the most reliable operation under the specific service conditions. Dual magnets are standard in all models. They provide reliable and positive switching. They also make the units immune to the vibration-induced false alarms and shutdowns.

  • Switch Action: Single point alarm
  • Specific Gravity: 0.3 to 2.4 units
  • Interface Differential: 0.1 unit minimum
  • Temperature: -350 to 1100°F
  • Pressure: -15 to 6000 PSIG
  • Process Connection: 1″, 1 ½”, or 2″ butt, stub, or socket weld; ANSI flanges or Greyloc hub

Operation

The Delta Controls Model 763Y Level Alarm provides a single switching output when the liquid level, usually steam condensate, passes the centerline of the body. The unit has its displacer in a cage mounted outside the process vessel. The external cage design is utilized to minimize 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 displacer sensor is held in position by a pivot shaft. A counterweight is located on the opposite side of the pivot shaft. The displacer moves up and down as the liquid level varies. This action causes a rotary motion of the counterweight/element as they pivot around the shaft. A drive magnet, embedded in the counterweight, is continuously coupled to the switch station magnet by their respective magnetic fields. The magnetic lines of force pass through the nonmagnetic barrier web and connect the two magnets. The magnets' poles are in opposition. When the drive magnet is rotated past the centerline of the station magnet; the magnetic repulsive force causes the station magnet to be driven against its stop in the opposite direction. This snap action is positive and fast. There is never an disengaged"neutral" position. The constantly engaged dual magnet design is insensitive to vibration. The station magnet is connected to an output switch which actuates and deactuates as the station magnet is alternately driven against the two stops. The counterweight design allows heavy displacers to be used in very high pressure and temperature applications.

Installation

The Delta Controls Model 763Y is mounted horizontally in a vertical riser with straight-through piping. To change the liquid level switching point add or subtract pipe lengths above and below the cage, then move the entire unit up or down to the desired switching elevation. The switch point band is halfway up (on the horizontal centerline) of the cage assembly. The switch point may be slightly higher or lower depending upon the actual specific gravity of the process liquid and the size sensing element.