Portable Viscometer 321 Sensor

A unique viscometer for in-tank blending and reaction monitoring

Cambridge Viscosity’s Portable 321 Viscometer is designed to be installed in a tank for continuous temperature and viscosity tracking.

Viscosity Range Icon

Viscosity Range: 0.2 to 20,000 centipoise (cP)

Repeatability Icon

Repeatability: 0.5%

Accuracy Icon

Accuracy: ± 1.0%

Maximum Temperature Icon

Maximum Temperature: 190°C (370°F)

Pressure Range Icon

Pressure Range: 1,000 psi (70.3 bar)

Wetted Parts Icon

Wetted Parts: 316L or Hastelloy

321 Sensor- Image (HR)

How a Viscometer Sensor Works

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Cambridge Viscosity's Portable 321 Viscometer Sensor Provides In-Tank Monitoring of Viscosity and Temperature


Viscosity  0.2 to 20,000 centipoise (cP)
Piston Ranges  0.2-2cP, 0.25-5cP, 0.5-10cP, 1-20cP,  
 2.5-50cP, 5-100cP, 10-200cP, 25-500cP, 
 50-1,000cP, 100-2,000cP, 250-5,000cP,
 500-10,000cP, 1,000-20,000cP
Viscosity Accuracy*  ± 1.0% 
Repeatability  ± 0.5% of Reading
Temperature Sensor  4 wire internal RTD
Wetted Materials  316L or Hastelloy
Maximum Particle Size  25-360 microns (Range Dependent)
Max Ambient Temperature

 375°F (190°C)

Max Operating Pressure  1,000 psi (70.3 bar)
Standard Cable Length  15 feet (4.5 meters)
 Requires VISCOpro electronics


  • TIIS Approved IIBT3 #TC15402
  • Approved for Class 1, Div. 1, Group C & D
  • Approved for EEx d IIC T2, -20C<Tamb<190C

Dimensions :

Viscometer Sensor 321 Portable Diagram






A Small But Powerful Sensor

Cambridge Viscosity’s Miniature Viscometer SPC 501 is used extensively for compressor, used oil analysis, on-engine, and hydraulic fluid applications. It is ideal for installations where form factor and small sample volume are important.


Our viscosity management technology is based on a simple and reliable electromagnetic concept.  Two coils move the piston back and forth magnetically at a constant force.  Proprietary circuitry analyzes the piston’s two-way travel time to measure absolute viscosity.


A built-in temperature detector (RTD) senses the actual temperature in the sampling chamber.  Constant in and out motion keeps samples fresh, mechanically scrubs the sampling area, and provides excellent viscosity tracking.


Measurements can be made in any of 6 different 20:1 viscosity ranges between 0.5 and 500 centipoise (cP).


Recommended fluid flow over the sensor is up to 30 cm/sec.



  • For Tanks and Vessels
  • Accurate and Reliable
  • One Moving Part, No Wear Points
  • All Wetted Parts, 316L Stainless Steel
  • Correlates with ASTM D445
  • Customer-Specified Stem Lengths
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