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663, 664, 666 & 668 (W)

Welded Chamber Mounted Level Switches

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663, 664, 666 & 668 (W)

For refinery and chemical process engineers, terminal operators, maintenance leaders, and EPC specifiers who need a reliable single-point level switch for pressurized vessels, separators, knock-out drums, and bypass chambers, the Omnitrol 663 / 664 / 666 / 668 (W) provides a long welded external chamber, factory-set specific gravity calibration, and proven displacer actuation for accurate, drift-free switching in demanding industrial services.

Unlike float, paddle, or electronic sensors that may fail in dirty, viscous, high-pressure, variable specific-gravity, or hazardous environments, the “W” Series delivers:

  • Tailored switching differential based on chamber size and fluid specific gravity
  • Hydrostatic testing at 1.5× design pressure
  • UL and CSA approvals
  • Material options including stainless steel
  • Optional stainless steel displacers for corrosive or clean-in-place applications

The result is a robust mechanical level switch designed for high-integrity industrial service where precision, reliability, and simplicity are essential.

663, 664, 666 & 668 (W)
663, 664, 666 & 668 (W)
663, 664, 666 & 668 (W)

Features

Long Welded Chamber Design

The extended body length allows precise sizing of switching differential to match your media specific gravity and application window, delivering reliable actuation points even where level changes are subtle.

Factory Specific Gravity Calibration

Each unit is calibrated to your specified liquid specific gravity at the factory, providing predictable switch behavior without field trial-and-error or commissioning delays.

Pressure Temperature Rating

Standard ratings up to 1000 psig at 500°F cover most refinery, chemical, and industrial services while preserving actuator integrity and long-term reliability.

Hydrostatic Testing Protocol

Every chamber is pressure-tested to 1.5 times its maximum design pressure before shipment, increasing confidence at startup and ensuring vessel integrity throughout service life.

Material Construction Flexibility

Chambers available in carbon steel, 304 stainless steel, or 316 stainless steel with optional stainless steel displacer to support corrosive, high-purity, or clean-in-place services.

Safety Certifications

UL and CSA approvals help satisfy plant safety standards, insurance requirements, and regulatory compliance obligations without additional field testing or documentation.

Applications

  • Tight Differential Control: For applications requiring precise trip points on moderate specific gravity liquids, the long chamber sized to your specifications stabilizes measurement and eliminates nuisance trips.
  • High Pressure Receivers: Operating reliably in vessels from 150 to 1000 psig at 500°F, these switches perform safely across typical plant pressure envelopes without actuator degradation.
  • Knock-Out Drums: Handles high-pressure separation vessels where reliable level switching protects downstream equipment and prevents carryover, with materials rated for the pressure and temperature extremes.
  • Corrosive Chemical Service: Optional 304 or 316 stainless steel chamber with stainless displacer resists chemical attack, providing extended service life in aggressive media without material degradation.
  • Interface Level Detection: The long chamber design with appropriate displacer material enables reliable switching at liquid-liquid interfaces, critical for separator vessels and phase separation applications.
  • Clean-In-Place Systems: Stainless steel construction meets hygienic standards for food, pharmaceutical, and biotechnology applications requiring frequent sanitization cycles and contamination-free operation.
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Specifications

Models

663W (3″), 664W (4″), 666W (6″), 668W (8″) chamber diameters.

Pressure/Temperature

150–1000 psig at 500 °F.

Materials

Chamber in CS/304SS/316SS; graphite displacer (standard); SS displacer optional.

Connections

1″ NPT top/bottom standard; other sizes/configurations available.

Calibration

Factory-set to application SG.

Testing & Approvals

Hydrostatically tested at 1.5× MDP; UL & CSA approved.

Switching Differential (typical @ standard SG)

  • 663W: standard SG 0.80, differential ~2-5/8″; min SG 0.70.
  • 664W: standard SG 0.70, differential ~2-1/8″; min SG 0.50.
  • 666W: standard SG 0.45, differential ~7/8″; min SG 0.35.
  • 668W: standard SG 0.35, differential ~3/4″; min SG 0.25.
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If you have questions not covered here, please contact the Cognesense support team for assistance.

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When should I choose the W-Series versus the F-Series?

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  • Choose W-Series when you need a long welded chamber for differential stability, interface service, or stainless-displacer applications.
  • Choose F-Series when your piping spec requires flanged connections.

When should I select the long welded “W” chamber over the short welded “C” chamber?

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Choose the “W” long welded chamber when you need a longer body length to achieve a larger, custom-sized switching differential, or when you specifically require interface service capability. The “C” chamber is compact for tight spaces but has a shorter fixed length and less flexibility for differential adjustment.

Is field calibration required?

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No — units are factory-calibrated to your SG. Contact us if SG varies by more than 0.1.

Is the switch suitable for hazardous environments?

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Fully approved for UL/CSA hazardous-location installations.

Can the chamber be removed or modified?

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The “W” is welded and intended for fixed installation — choose the F-series if removable flanged installation is desired.

Does the switch require electrical power?

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No — purely mechanical actuation, providing fail-safe, drift-free performance.

Can a single actuator switch be used for both high-level and low-level alarms simultaneously?

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No. The 66xW series is a single-actuator design, meaning it provides only one trip point (either High or Low) per unit. If you need two setpoints (e.g. pump start/stop or Hi/Low alarm) in one chamber, you should select the dual-actuator Omnitrol 76x series.

Summary

The  Omnitrol  663/664/666/668(W) is the go-to long welded chamber-mounted level switch when you need tailored differential, higher pressure/temperature capability, and material flexibility, with the added confidence of factory SG calibration and UL/CSA approvals. It slots neatly alongside the “C” (short welded) and “F” (flanged) families so you can standardize on the exact chamber geometry the application demands while keeping a common switch platform across the plant.

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