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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) Actuator Welded Chamber Mounted Switch

Details

The Omnitrol W-Series is engineered for tight alarm bands, high pressure service, corrosive media, and interface detection in demanding industrial environments.

Typical applications include:

Process heaters and reactors
Separator drums and knock-out pots
Amine and caustic wash systems
Boiler and steam-cycle vessels
Water and oil interface tanks
High-pressure utility and hydrocarbon systems

The long welded chamber design provides additional separation between the displacer and the actuator. This allows an application-specific switching differential, which is especially beneficial when:

Fluid specific gravity varies
Process agitation is present
Liquid interface detection is required

W-Series Advantages

Requirement	W-Series Advantage
Precise Differential Trip	Extended chamber enables stable, predictable actuation
High Pressure or High Temperature Service	Rated up to 1000 psig at 500 °F
Corrosion Resistance	304 / 316 stainless steel chamber and optional stainless displacer
Hazardous Area Compliance	UL and CSA certified

Applications

Tight Differential / Moderate Specific Gravity: The extended chamber is sized according to media specific gravity and the desired switching differential, producing more precise trip points and minimizing nuisance alarms.
Interface Detection: Supports reliable oil and water or condensate and hydrocarbon interface detection, providing improved separation control and reduced carryover.
High Pressure Receivers: The 1000 psig at 500 °F rating allows safe operation within typical industrial pressure envelopes.
Corrosive or Hygienic Media: Optional 304 or 316 stainless steel chambers and stainless displacers provide corrosion resistance and support compliance with sanitary or corrosion-control standards.

Technical Specifications

Parameter

Specification

Models

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

Actuation

Single-point mechanical displacer switch

Pressure Rating

150–1000 psig at 500 °F

Chamber Materials

Carbon steel, 304 stainless steel, 316 stainless steel

Displacer

Graphite standard; stainless steel optional

Process Connections

1″ NPT process ports (other options available)

Calibration

Factory set for specific gravity (consult if SG varies more than 0.1)

Testing

Hydrostatic tested to 1.5× maximum design pressure

Certifications

UL and CSA

Typical Applications

High or low level alarms, shutdown trips, pump protection

Typical Switching Differentials (Standard SG)

Model	Standard SG	Differential	Minimum SG
663W	0.80	~2-5/8″	0.70
664W	0.70	~2-1/8″	0.50
666W	0.45	~7/8″	0.35
668W	0.35	~3/4″	0.25

2026 COST ESTIMATE

Support

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

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?

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?

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?

Fully approved for UL/CSA hazardous-location installations.

Can the chamber be removed or modified?

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?

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?

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.