Cognesense - Measure, Monitor, Protect

764 / 766 / 768 (W)

For refinery and chemical plant engineers, terminal operations teams, maintenance supervisors, and EPC designers who need two independent mechanical level trips in demanding, pressurized applications, the Omnitrol 764W / 766W / 768W provides dual-actuator displacer switching inside a welded bypass chamber.

Unlike flanged solutions that introduce additional gasketed joints and potential leak paths, the welded W-Series offers:

Two switching points in a single chamber
Extended welded body for predictable switching differential
Factory-set specific gravity calibration
Hydrostatic proof testing at 1.5× design pressure
Service capability up to 1000 psig at 500 °F
UL and CSA hazardous-location approvals

This design is ideal for pump start and stop control, high-high or low-low protection, and critical shutdown applications where mechanical certainty, safety, and long-term reliability are essential.

764 / 766 / 768 (W) Actuator Welded Chamber

Details

The 764W / 766W / 768W welded chamber series is engineered for applications where:

Two level setpoints are required while minimizing vessel penetrations
Mechanical reliability is preferred over electronics in hot, dirty, or turbulent processes
High system integrity and minimal leak paths are required
Pump differential control or high-high shutdown logic is necessary
Extended chamber geometry improves differential stability

Typical Applications

Pump start and stop control for sumps, separators, and knock-out drums
High and high-high overfill alarms for safety programs and API practices
Level shutdown protection for steam systems, heater treaters, and process vessels
High-pressure hydrocarbon or chemical systems where electronic sensors may struggle

Standard actuator spacing provides approximately 4″ switching differential (adjustable about 2–4″), allowing the system to respond appropriately to process surge and preventing pump short-cycling.

Applications

Overfill or Low-Level Protection: Provides two independent trips in a single welded chamber, reducing piping complexity, minimizing penetrations, and lowering leak risk for critical safety systems.
Pump Control (Start and Stop): Dual actuators stabilize sump or tank levels, reducing short cycling and extending pump life.
High-Temperature and High-Pressure Service: The 1000 psig / 500 °F rating enables reliable mechanical switching where electronic devices or lower-rated equipment may fail.
Space-Constrained Retrofits: The long welded chamber allows compact side mounting while still providing dual-point level control without internal stilling wells.

Technical Specifications

Parameter

Specification

Series

764W / 766W / 768W (dual actuator, welded chamber)

Chamber Diameter

764W: 4″, 766W: 6″, 768W: 8″

Actuation

Two independent mechanical switch points

Switching Gap

Approximately 4″ standard, adjustable about 2–4″

Specific Gravity

Maximum SG 1.4, factory calibrated

Pressure Rating

150–1000 psig at 500 °F

Chamber Materials

Carbon steel, 304 stainless steel, 316 stainless steel

Displacer

Graphite (standard) or optional stainless steel

Process Connections

1″ NPT standard; other options available

Verification

Hydrostatic tested to 1.5× design pressure

Electrical Output

SPDT or DPDT switch options

Certifications

UL and CSA approved

Typical Use

Pump control, HI / HI-HI alarms, safety shutdowns

Limitation

Not intended for interface measurement applications

2026 COST ESTIMATE

Support

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

Why choose the welded W-Series instead of a flanged chamber?

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Use the W-series when you want fewer gasket joints, a simplified welded body, and the ability to specify special lengths.
Choose the F-series when removable, flanged isolation is required. The main advantage is long-term integrity and reduced fugitive emissions. The welded body eliminates the gasketed joints required by flanged designs, which are potential points of failure and leakage.
The “W” chamber is also often selected when special non-standard body lengths are needed.

Do these devices require field calibration?

No — they ship factory-set to your specific gravity.

Why is the actuator spacing adjustable?

The actuator spacing defines the switching differential (the distance between the START and STOP points for a pump). Adjusting this spacing allows engineers to tailor the control logic to the vessel’s dynamics, preventing the pump from running on and off too quickly (short-cycling) and extending pump life.

How many vessel nozzles are required for installation?

One instrument — one chamber — two independent setpoints. No additional vessel penetration required.

What environments are these switches best suited for?

High-pressure, hot, corrosive, and hazardous service including refineries, chemical plants, terminal operations, and utilities.

⁠Can this switch be used for pump control?

Yes — this is a primary use case, with adjustable differential to prevent pump short-cycling.