Mercoid Series 190
Single Stage Top Mount Displacer Type Level Control — Fixed or Adjustable Deadband, For Pumps or Alarms
Single Stage • NEMA 4X • UL Approved
One of the most versatile level controls available, the Mercoid Series 190 can be used on all types of tank or sump level control applications. 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 — as the liquid level rises and their weight decreases, the tension on the spring is decreased.
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. The Series 190 provides single stage control for pump or alarm service with fixed or adjustable deadband.
How Displacer Controls Work
Unlike float-type level controls that ride on the liquid surface, Mercoid displacer controls are suspended on a coil spring inside the tank. They operate on Archimedes’ principle: a submerged object weighs less in liquid than in air. As the liquid level rises around the displacer, buoyancy increases and the apparent weight of the displacer decreases, reducing spring tension. This change in tension actuates the switch.
Turbulence Resistant
Spring suspension isolates the displacer from surface turbulence that would cause false trips in float-type controls.
Pressure Independent
Operates on buoyancy, not surface position — unaffected by tank pressure changes.
Viscous & Dirty Liquids
Ideal for applications where floats would become coated or stuck.
Key Features
Specifications
Popular Model
B190-WT-7810-1.0
Liquid level switch/control, SPDT snap switch, watertight enclosure, specific gravity 1.0
Contact us for custom configurations including different enclosures, switch types, specific gravity settings, flange materials, or extended cable lengths.
Enclosure Options
| Enclosure Type | NEMA Rating | Approx. Weight |
|---|---|---|
| General Purpose | NEMA 1 | 28 lb (12.7 kg) |
| Watertight (Standard) | NEMA 4X | 28 lb (12.7 kg) |
| Explosion-Proof | NEMA 7 & 9 | 32 lb (14.5 kg) |
| Explosion-Proof / Vapor-Proof | NEMA 7 & 9 | 32 lb (14.5 kg) |
Ready to order or need a custom configuration?
Contact our team for pricing, availability, and custom enclosures, flanges, or displacer materials.