Model 763

SKU: 763

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/li>
  • 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 Models 763-36 and -37 provide output switching at a single elevation of a varying liquid level (usually steam condensate). The unit is mounted outside the process vessel. 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 testing and maintenance, without disturbing the operation of the process.

The vertical counterweight is inside the cooling extension tube. It also offsets most of the weight of the heavy wall displacer; which allows operation in low SPG liquids at high vapor pressures. The displacer sensor moves up and down as the liquid level varies. The counterweight,, with drive magnet, is connected across the pivot shaft from the sensing element. The drive magnet is located on top of the counterweight and also moves up and down. The drive magnet 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 moves 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 alternatively driven against the two stops. The counterweight design allows heavy (even solid) displacers to be used in very high temperature and pressure applications.

Installation

The Delta Controls Models 763-36 and -37 are mounted horizontally in a vertical riser with straight through piping. The switching point band is halfway up on the cage (at the cage horizontal centerline). This switch point may be slightly higher or lower depending on the SPG of the process. The unit should be mounted close to the vessel whose level is to be monitored; if this is not possible, then slope the connecting pipes 1" per foot to drain any sediment back towards the vessels.

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