PR21 Series | Process Refractometer

Process refractometers are built directly into pipework and boilers or operated in the bypass. They are ideal for process monitoring, control and product separation in a variety of industries (chemicals, beverages, food and sugar).

The monitoring of refractive index is a popular method of inline quality control in many process industries, including pulp and paper, food and beverage, chemical and pharmaceutical, and wastewater. It provides real-time data for quality control and Good Manufacturing Practice (GMP), and can be used to monitor qualities such as concentration of a solution, density of a fluid, or % Brix. An inline process refractometer is installed directly into pipework or a boiler, with standard connections for easy assembly.

The PR21 has been developed for direct insertion into pipes and boilers, for process monitoring, control and separation of products in such industries as chemicals, beverages, food, pulp, paper, and sugar. Installation in a pipeline or tank is simple, as no bypass is necessary. Three interfaces are available for this unit: Analogue 0/4-20 mA, Ethernet, or PROFIBUS.

Special Features:
• Excellent value
• Wide measurement range from 1.3300 –1.5600 nD; 0–95 %Brix
• Adjustable measurement interval (min. 3 s)
• Password-protected
• Prism in the sample chamber is easy to clean
• User-friendly interfaces for direct connection to a PLC
• Very easy to install, no special requirements

Fields of Application:
• Beverages
• Food
• Sugar/sweeteners
• Chemicals
• Flavours
• Petrochemicals
• Cosmetics / hygiene
• Metalworking
• Pharmaceuticals
• Water / effluent
• Education / research

*The prism is specially designed to prevent solid materials from collecting on the surface, even after extended periods of use.

Specifications Measurement accuracy Resolution Product temperature Ambient temperature
PR21S ±0.0002 nD
±0.2 %Brix
0.0001 nD
0.1 %Brix
< 60 °C < 40 °C
PR21S-T < 160 °C < 60 °C
PR21H ±0.00002 nD
±0.02 %Brix
0.00001 nD
0.01 %Brix
< 60 °C < 40 °C
PR21H-T < 160 °C < 60 °C

Measurement mode Refractive index [nD],
Sugar content [%Brix],
User defined [%]
Measurement interval 3–60 s
Temp. sensor PT100
Temp. measurement -10–200 °C
Temp. resolution 0.1 °C
Temp. measurement accuracy ± 0.2 °C
Temp. compensation ICUMSA, arbitrary
Process temperature -5–160 °C
Ambient temperature 0–60 °C
Prism Sapphire
Illumination LED 590 nm
(est. life: >100.000 h)
Housing Stainless steel, Cast aluminium,
Interfaces Analogue 0/4-20 mA,
PROFIBUS (optional)
Protection class IP65
Working voltage 24 V
Dimensions in cm 18.0 x 19.0 x 18.0
Weight 3.5 kg

Ordering Information: Please call for pricing details


PRB21 | Bypass Process Refractometer
While operating the PRB21 The sample is fed into the measurement chamber through a stainless steel bypass. The prism is made of particularly scratch-resistant sapphire. The PRB21 is generally connected to a PLC and provides continuous process control. Small sample volumes suffice for this. The measurement interval is adjustable (>3 s) and the measurement result is not affected by either the colour or the turbidity of the sample.

The PRB21 has various interfaces and can also be supplied with PROFIBUS on request. A display is also available for visual monitoring. Automatic temperature compensation can be obtained by means of the internal temperature sensor and the measured temperature fed to the PLC.

Measurement range 1.3200 nD–1.5600 nD
0–95 %Brix
Accuracy PR-H: ±0.00002 nD;
± 0.02 %Brix
PR-S: ±0.0002 nD;
± 0.2 %Brix
Resolution PRB-H: 0.00001 nD;
0.01 %Brix
PRB-S: 0.0001 nD;
0.1 %Brix
Measurement units Refractive Index [nD]
Saccharose [%Brix]
Invert Sugar [%Brix]
Glucose [%Brix]
Fructose [%Brix]
Measurement interval 3–60 s
Temperature sensor PT100
Temperature measurement -10–99.9 °C
Temperature resolution 0.1 °C
Temperature accuracy ±0.2 °C
Temperature compensation ICUMSA, arbitrary
Ambient temperature 0–40 °C
Prism Sapphire
Illumination LED 590 nm
(est. life: >100.000 h)
Housing Cast aluminium, powdercoated
Interfaces RS-232,
analogue 0/4–20 mA
Protection class IP65
Working voltage 24 V
Display (optional) LCD 120 x 32 Pixel
Dimensions in cm 18.0 x 10.0 x 18.0
Weight 3 kg


Ordering Information: Please call for pricing detailss




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