Cognesense - Measure, Monitor, Protect

666 / 668 (C) Switch

For refinery engineers, chemical plant operators, power generation teams, boiler and steam system designers, and EPC specifiers who need high-pressure, high-temperature point-level protection with mechanical certainty, the Omnitrol 666 / 668 (C) delivers compact, chamber-mounted displacer switching engineered for extreme duty environments.

Unlike electronic switches that can drift or fail under heat, vibration, and pressure cycling, the Omnitrol 666 / 668 (C) uses proven mechanical displacer technology, welded “C”-style chambers, and field-proven magnetic snap-action switching to ensure fail-safe level protection for liquids, including low-specific-gravity hydrocarbons, solvents, and steam condensate.

Ideal where space is limited, reliability is critical, and electronics are not preferred, this model provides a field-proven solution for pressurized vessels, blow-down drums, steam systems, condensate pots, and hazardous media tanks.

666 / 668 (C) Switch

Details

The Omnitrol 666 / 668 (C) provides single-point actuation within a short welded chamber, delivering a compact footprint while maintaining maximum reliability in demanding industrial environments.

The displacer detects liquid level changes through Archimedes’ principle. As buoyancy changes, the displacer moves and activates a magnetically coupled snap-action switch that is unaffected by foam, turbulence, vapor layers, or dielectric variation.

Because the device operates mechanically:

No calibration is required
There are no electronic failure modes
Installation remains fully external to the vessel

This results in dependable level protection for high-pressure vessels, low-specific-gravity fuels, steam systems, chemical processes, and critical shutdown applications.

The 666 / 668 (C) is designed as the compact alternative to the larger “W” and “F” chamber versions, making it ideal for single-point alarms in tight piping arrangements or skid-mounted equipment.

Applications

High-Pressure Vessels: Provides reliable mechanical alarms or shutdown signals in extreme pressure and temperature environments such as boilers and process vessels.
Safety Interlocks: Commonly used in systems like boilers and steam drums to ensure dependable water cutoff and prevent equipment damage.
Low-Specific-Gravity Liquids: Accurately detects level changes in light fuels and solvents where other technologies may struggle.
Chemical Tanks and Reactors: External chamber isolation and explosion-proof housing allow safe operation and maintenance in corrosive or hazardous vapor environments.

Technical Specifications

Parameter

Specification

Technology

Displacer-actuated mechanical level switch

Chamber Type

Short welded “C”-style external chamber

Models

666 (C), 668 (C)

Actuation

Single alarm or trip point

Displacer Options

Graphite (standard) or stainless steel

Mounting Connections

Side or bottom process connections (1″ NPT standard; flange options available)

Housing Options

Weatherproof, explosion-proof, vapor-proof, rain-tight

Hazardous Ratings

Class I Div 1 Groups B, C, D; Class II Groups E, F, G options

Temperature / Pressure

Designed for high-pressure and high-temperature service (varies by model configuration)

Switch Output

Mechanical snap-action microswitch

Power Requirement

None — fully mechanical operation

Typical Applications

High or low level trip, pump protection, boiler cutoff, shutdown interlock

2026 COST ESTIMATE

Support

If you have questions not covered here, please contact support for assistance.

Why choose a chamber-mounted mechanical switch instead of an electronic device?

−

Mechanical displacer switches offer fail-safe action, no drift, and immunity to heat and EMI — ideal for safety and steam service.

What types of fluids work with the 666 / 668 (C)?

Hydrocarbons, condensate, light solvents, process water, and most refinery/chemical liquids — including low-specific-gravity fluids.

Does this model support multiple switch points?

No — the 666/668(C) is a single-point switch.

Can this unit be serviced without opening the tank?

Yes — all mechanical components are external, enabling safe isolation and maintenance.

⁠Is it suitable for boiler and steam service?

Yes — its pressure-rated chamber and mechanical design make it ideal for steam drums, blow-down systems, and condensate vessels.

What makes this model effective for low-specific-gravity fluids?

The displacer system is engineered to sense very small density changes, outperforming floats and ultrasonic devices in LPG/NGL and solvent service.