KRÜSS PRB21S Bypass Process Refractometer
A.KRÜSS Optronic

KRÜSS PRB21S Bypass Process Refractometer

Series: Process refractometer

Model: PRB21S

The PRB21S uses a bypass flow cell for continuous refractive-index and %Brix measurement without interrupting the main process.

Application / measured object:

Continuous refractive index nD, %Brix and user-defined concentration-scale measurement of liquids in a tank, vessel or pipeline bypass.

Application area:

Product overview

The PRB21S connects to the process with hoses so that part of the main process stream passes through the bypass measuring cell by pumping or hydrostatic pressure, enabling uninterrupted continuous measurement.

Advantages

Process installation and continuous monitoring

  • A hose-connected bypass routes a partial process flow through the cell by pumping or hydrostatic pressure, without interrupting the process.
  • Scratch-resistant, chemically resistant sapphire prism and stainless-steel measuring chamber.
  • Relative process pressure 0–2 bar; process temperature 10–60 °C.
PRB21S bypass measurement connection.
PRB21S bypass measurement connection.

Scales, temperature compensation and cleaning

  • Refractive-index nD, sucrose %Brix and user-defined scales; integrated temperature-monitoring sensor.
  • ICUMSA or user-defined temperature compensation.
  • IP65 instrument and IP67 connections; CIP cleaning up to 120 °C, distinct from the normal measuring-temperature limit.

Control-system connections

  • RS-232, separate RS-232 for a display, two 0/4–20 mA analogue outputs, one relay input and two relay outputs.
  • PC-based setup and adjustment; a separately purchased display provides local value and temperature readout.

Technical data

Item Specification
Measurement range nD 1.3200–1.5600; 0–95 %Brix
Measurement accuracy nD ±0.0002; ±0.2 %Brix
Resolution nD 0.0001; 0.1 %Brix
Measurement period Approx. 10 s
Wavelength 589 nm
Process pressure (relative) 0–2 bar
Process temperature 10–60 °C
Ambient temperature 0–40 °C
Ambient humidity 10–90% (non-condensing)
Temperature-measurement accuracy ±0.2 °C
Scales Refractive index nD, sucrose concentration %Brix and user-defined scales
Adjustment and setup Via PC/laptop; firmware is included and separate software is not required
Parts in contact with the sample Sapphire, PTFE, FKM and stainless steel 1.4305
Mounting Bypass with flow cell
Additional features ICUMSA or freely definable temperature compensation; IP65 overall (IP67 connections); CIP capable up to 120 °C
Interfaces 1 × RS-232, 1 × RS-232 for display, 2 × analogue 0(4)–20 mA, 1 × relay input and 2 × relay outputs
Dimensions (W × H × D) 220 × 110 × 220 mm
Weight 3 kg
Operating voltage 24 VDC (18–30 VDC)
Power consumption in measuring mode 5 W without display; 6 W with display
Maximum power consumption 6 W without display; 7 W with display

Measurement accuracy is specified at λ = 589 nm, 20 °C, 1013 hPa and 50% relative humidity.

Application areas

For bypass real-time concentration and quality monitoring in chemical, petrochemical, automotive and aircraft manufacturing, food, sugar, beverage and wastewater applications.

Related accessories

  • O-ring seal for process refractometers.
  • Pre-assembled connection cable set for the PR21 series.
  • PR21-series display for measured value and temperature.

Service support

  • Experienced specialists provide product selection, application and operation support.
  • Calibration, maintenance and maintenance contracts can be discussed as required.

Selection guidance

PRB21S suits processes where a bypass can be installed and sample flow needs independent control. Selection should confirm media compatibility with wetted materials, pressure and temperature, CIP conditions, installation point, power supply, and analogue and relay interface requirements.