764/766/768 (W) Actuator Welded Chamber

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Overview

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 — without adding vessel penetrations or gasketed joints — the Omnitrol 764W / 766W / 768W delivers dual-actuator displacer switching inside a welded bypass chamber.

Unlike flanged solutions that introduce additional leak paths, the welded W-series provides:
  • Two switching points in one chamber
  • Extended welded body for predictable differential
  • Factory-set specific gravity calibration
  • Hydrostatic proof testing at 1.5× design pressure
  • Service to 1000 psig @ 500 °F
  • UL / CSA hazardous-location approvals

This makes it ideal for pump start/stop, high-high / low-low protection, and mission-critical shutdown applications where mechanical certainty, safety, and long-term reliability matter most.

Actuator Welded Chamber Mounted Switch

Features

Durability

Dual Independent Actuators

Two mechanically separate switching points — perfect for HI/HI-HI alarms or pump start/stop logic.

Welded Chamber Construction

Fewer leak paths and no gasketed joints — superior integrity in pressurized service.

Factory SG Calibration

Ships tuned for your fluid’s specific gravity for accurate, nuisance-free switching.

High-Pressure / High-Temperature Performance

Rated up to 1000 psig @ 500 °F for refinery and chemical service.

Hydrostatic Test Certification

Every unit pressure-tested at 1.5× maximum design pressure.

Material Flexibility

Carbon steel, 304 or 316 stainless steel chamber options; graphite or optional SS displacer.

Hazardous-Area Ready

UL & CSA Approvals

Built for hazardous industrial environments.

Details

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

  • Two level setpoints are required, but vessel penetrations must be minimized
  • Mechanical reliability is preferred over electronics in hot, dirty, or turbulent processes
  • High integrity and minimal leak paths are a priority
  • Pump differential control or high-high shutdown logic is needed
  • Long chamber geometry improves differential stability

Typical Duties Include:

  • Pump start/stop control for sumps, separators, and knock-out drums
  • High / high-high overfill alarms per safety programs and API practices
  • Level shutdown for steam systems, heater treaters, and process vessels
  • High-pressure hydrocarbon and chemical circuits where electronics struggle

Standard spacing provides ~4″ differential (adjustable approx. 2–4″), allowing measured response to process surge and preventing short-cycling.

Applications

  • Overfill or Low-Level Protection: Provides two independent trips in one welded chamber, resulting in simpler piping, fewer penetrations, and a lower leak risk for critical safety applications.
  • Pump Control (Start/Stop): Uses the dual actuators to stabilize sump or tank levels, reducing short-cycling and extending pump life.
  • Hot, High-Pressure Services: The1000 psig/ 500 °F rating ensures dependable mechanical switching where electronics or lower-rated materials would struggle.
  • Space-Constrained Retrofits: The long, welded chamber provides a compact side-mount solution that can manage dual-point control without needing 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
~4″ standard, adjustable approx. 2–4″
Specific Gravity
Max SG 1.4; factory-calibrated
Pressure Ratings Available
150–1000 psig @ 500 °F
Chamber Materials
Carbon steel, 304 SS, 316 SS
Displacer
Graphite (standard) or optional stainless steel
Process Connections
1″ NPT standard; other options available
Verification
Hydrostatic test to 1.5× design pressure
Electrical
SPDT / DPDT switch options
Certifications
UL & CSA approved
Use Cases
Pump control, HI/HI-HI alarms, safety shutdowns
Limit Note
Not intended for interface measurement applications

Documents and Downloads

Product Flyer

Have a look at the flyer to get all the tech specs and product features. Brochure

User Manual

Read the manual for detailed information and instructions. Manual

Calibrations

Check out a sample cert from our calibration lab. Certificate

Contact Support

If you have a question that we have not covered then just get in touch and we’ll be happy to help.

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FAQs

We have tried to answer the most common questions we are asked here.

  • 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.

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

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.

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

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

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