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 services.
Unlike float, paddle, or electronic sensors that can fail in dirty, viscous, high-pressure, variable-SG, or hazardous environments, the “W” series delivers:
The result is a robust, mechanically reliable level switch purpose-built for high-integrity industrial service where precision, uptime, and simplicity matter.
Extended body provides precise differential control and supports interface applications.
Ships calibrated to your media — no field tuning required for switching accuracy.
Rated up to 1000 psig at 500 °F across refinery & chemical duty ranges.
Ensures chamber integrity prior to commissioning.
Carbon steel, 304 / 316 stainless steel chambers; optional SS displacer for corrosive service.
UL & CSA approved for Classified industrial environments.
No vessel penetration for maintenance — isolate and service without opening the vessel.
The Omnitrol W-series is engineered for tight alarm bands, high pressure, corrosive media, and interface control in critical applications such as:
The long welded chamber provides greater distance between displacer and actuator, allowing application-tuned switching differential — particularly valuable when media SG changes, agitation exists, or interface separation matters.
Use the W-series when you need:
| Requirement | W-Series Advantage |
|---|---|
|
Precise Differential Trip |
Extended chamber for stable actuation |
|
High Pressure or Hot Service |
Up to 1000 psig @ 500°F |
|
Corrosion Resistance |
304/316SS chamber & SS displacer option |
|
Hazardous Area Compliance |
UL / CSA certifications |
| Parameter | Specification |
|---|---|
|
Models |
663W (3″), 664W (4″), 666W (6″), 668W (8″) chamber sizes |
|
Actuation |
Single-point mechanical displacer switch |
|
Pressure Rating |
150–1000 psig @ 500 °F |
|
Chamber Materials |
Carbon steel, 304 SS, 316 SS |
|
Displacer |
Graphite standard; stainless optional |
|
Connections |
1″ NPT process ports (others available) |
|
Calibration |
Factory SG-set (consult if SG varies >0.1) |
|
Testing |
Hydrotested to 1.5× MDP |
|
Approvals |
UL & CSA |
|
Application |
High/low alarm, trip, pump protection |
Typical Switching Differentials (Standard SG)
| Model | Std SG | Differential | Min 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 |
Have a look at the flyer to get all the tech specs and product features.
Brochure
Read the manual for detailed information and instructions.
Manual
Check out a sample cert from our calibration lab.
Certificate
If you have a question that we have not covered then just get in touch and we’ll be happy to help.
We have tried to answer the most common questions we are asked here.
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.
No — units are factory-calibrated to your SG. Contact us if SG varies by more than 0.1.
Fully approved for UL/CSA hazardous-location installations.
The “W” is welded and intended for fixed installation — choose the F-series if removable flanged installation is desired.
No — purely mechanical actuation, providing fail-safe, drift-free performance.
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.