Series B-190 Single Stage Top Mount Displacer Type Level Control

Brand: Dwyer Instruments, LLC

The most versatile liquid level controls in our line, displacer controls can be used to trigger alarms, provide shutdown or operate pumps.

Mercoid® Displacer Controls use displacers that do not float on the surface of liquids, but are suspended on a coil spring. They work on the principle that submerged solids weigh less in liquids, and as the liquid level rises and their weight decreases, the tension on the spring by which they are suspended is decreased.

This allows the spring to move the cable and armature upward, actuating the hermetically sealed switches. Because they work on a different principle than float type liquid level controls, displacers are not affected by turbulence, or pressure, and are excellent for applications with viscous or dirty liquids.

Dimensions are based on 316SS displacers with 4" minimum flange type control. All dimensions are approximate and will vary depending on specific gravity, temperature, displacer material and size. Critical dimensions must be verified with the factory before placing order.

Standard Construction
316SS displacers, 10 foot 316SS cable and stops, 49 125# CI flange: for operation in specific gravities as low as 0.5 and a maximum temperature of 200° F (93° C).

For special conditions, other choices include: 316SS displacers: longer cable: monel or hastelloy cable and stops: other flange sizes, materials or pressure ratings, or 3/4" NPT top connection in lieu of flange.
  • Extremely versatile design
  • Displacers are suspended on a coil spring and do not float on the surface of liquids and are unaffected by turbulence or pressure
  • Excellent for applications with viscous or dirty liquids


Approvals & Certifications

  • UL

Cable Length

  • 10 feet (3 metres)
  • Optional up to 100 feet (30.5 m)

Cable Material

  • 316 Stainless Steel

Conduit Connection

  • 3/4” NPT Female

Deadband, Approximate

  • Adjustable by Moving Displacers

Electrical Connectors

  • Screw Terminal

Electrical Rating

  • 0.25 A at 250 Vdc - Resistive Hermetically Sealed Snap Switch
  • 0.5 A at 125 Vdc Resistive - Snap Switch
  • 12 A at 120 Vac - Snap Switch
  • 2 A at 240 Vac/Vdc - Mercury Switch
  • 4 A at 120 Vac/dc - Mercury Switch
  • 5 A at 120 Vac Resistive - Hermetically Sealed Snap Switch
  • 5 A at 240 Vac Resistive - Hermetically Sealed Snap Switch
  • 5 A at 30 Vdc Resistive - Hermetically Sealed Snap Switch

Environmental Protection

  • NEMA 4X

Fluid Specific Gravity

  • 0.5 to 1.2 Settable


  • Compatible Liquids

Mounting Position

  • Vertical

Spring Material

  • 316 Stainless Steel
  • Inconel

Supply Pressure

  • psig: 125 (kPa: 861.8, bar: 8.6)

Switch Type

  • DPDT Optional or Two Stage
  • SPDT

Temperature Range

  • 0° to 93.3° C (32° to 200° F)

Wetted Materials

  • 304 Stainless Steel
  • 316 Stainless Steel
  • Carbon Graphite
  • Porcelain

  • Pumping Stations
  • Foaming Liquids
  • Sanitary / Sewage Treatment
  • Paints & Varnishes
  • Agitated or Turbulent Fluids
  • Heavy Oil Refineries
  • Chemical Plants
  • Power Generating Stations
  • Viscous or Dirty Liquids
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