Level Controllers

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740 Top Mount Displacer Control

The Model 740 Series are displacer-operated units designed for internal mounting through the top of the process vessel and provide high pressure capabilities with low specific gravity ratings within the petroleum, power and natural gas industries. The use of displacers allows for a narrow or wide-switching differential, field adjustable switch points, high pressure applications and multiple switching points by means of dual switching mechanisms.

Operation

The stainless steel float/displacer, which is heavier than the liquid, is suspended by a spring. When liquid rises around the displacer, a buoyancy force is produced, which causes the effective weight of the displacer to change. This causes the spring to retract slightly to a new equilibrium position. When the spring retracts, the attraction sleeve also moves upward into the field of the external magnet. The magnet moves forward toward the attraction sleeve that actuates the micro switch.

Displacer Advantages

As the liquid level rises, the buoyancy force produced by the displacer causes the range spring to seek a new balance.

1. Ability to withstand higher pressure than a float, since displacers can be solid or constructed with a much heavier wall.

2. Allows wide switching differentials.

3. Allows switch point to be adjusted by moving the displacer up or down.

  • Construction Versatility: Standard Level Control includes Stainless Steel Displacer and Carbon Steel NPT or flanged tank connections. Consult factory for other materials.

Explosion Proof: CSA APPROVED

  • Class I, Division I, Groups C & D
  • Class II, Groups E, F & G
  • Class III, Enclosure Type 4

Various Models: A wide selection of connection, trim materials and switch mechanisms are available

  • Switch Housing . . . . . . . . . . . . . Explosion Proof Cast Aluminum
  • Operating Pressure . . . . . . . . . . . . . . . . . . . . . . 1000 psi Max.
  • Operating Temperature . . . . . . . . . . . . . . . . . . . . . . 450˚F Max.
  • Minimum Specific Gravity . . . . . . . . . . . . . . . . . . . . . . . . . 0.60
  • Electrical Connections . . . . . . . . . . . . 1 1 /4″ Female Pipe Thread
  • Electrical Contacts . . . . . . . . . . . . . SPDT Micro Switch standard