RFM990-AUS32 Refractometer

RFM900 Refractometer Prism




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RFM990-AUS32 Refractometer

The RFM990-AUS32 is an extremely high accuracy Refractometer specifically designed to meet the stringent needs of the chemical manufacturing industry supplying Urea solutions for the automotive industry and fleet management. 

Of particular interest is it’s compliance with the strictest of ISO procedures in relation to the manufacture of Diesel Exhaust Fluids, such as AUS and AdBlue®.

ISO 22241-2 dictates the highest level of measurement must be achieved under the tightest limits of temperature control. The RFM990-AUS32 is the only refractometer on the market that complies in terms of refractive index and temperature measurement/control specifications. In addition, the instrument is fitted with specific Urea scales and temperature compensation, so even the slightest movement in temperature will be corrected. 

Being part of the RFM900 series of refractometers, user of the RFM990-AUS32 will also benefit from other unique features such as RFID user identity/clearance, significant on-board data storage, calibration audit trails and a methods system that makes changing instrument parameters a simple two-button process. Full details of these features can be seen by visiting the RFM900 section of the Bellingham + Stanley Internet site.

No matter how good the instrument performance, without good verification, it is not possible to confirm the instrument meets the specification laid down in ISO 22241-2. Bellingham + Stanley offer a new UKAS Certified Reference Material for this purpose at precisely the correct RI value.
Measurement Specifications

Refractive Index (RI)
% Urea mass/mass (AUS32)

1.33 – 1.70

Refractive Index
% Urea mass/mass (AUS32)


Refractive Index
% Urea mass/mass (AUS32)


Refractive Index
% Urea mass/mass (AUS32)

Other Scales User defined – Urea % (AUS32), DEF, FSII  etc. or custom scales, loaded by PC software
Automatic Temperature Compensation Urea, ICUMSA (sugar), AG, None or User Defined
Temperature Control Internal Peltier Device
Temperature Accuracy ±0.02 °C (at 20 °C)
Temperature Stability ±0.01 °C (at 20 °C)
Working Temperature Range

0 °C or 10°C below ambient which ever is the greater to 80°C
(for AUS32 performance – 20°C is mandatory)

Temperature Stability Checks

None/delay time/repeatability/Smart
(independently set by Method)

Sample Temperature Range 20 to 30 °C
Reading Time (seconds) 15
Ambient Humidity Range < 90% RH
Physical Specifications
Prism Artificial Sapphire
Prism Dish 316 Stainless Steel
Interfaces 3 x USB (A), 1 x USB (B), 1 x Ethernet, 1 x Serial (RS232)
Sample Illumination Light Emitting Diode (life 100,000hr +) 589nm
Case Material ABS
Prism Gasket Kalrez®
Order Codes
19-73 RFM990-AUS32 Automatic Digital Refractometer for high accuracy measurement in accordance with ISO 22241-2 – Analysis of Aqueous Urea Solutions.

Certified Reference Material for AUS-32 refractometer.  
1.38290 RI equivalent to 32.5% AUS. (K=2: ±0.000011 RI),
15ml dropper bottle, 6-weeks shelf life. Contract Supply only. 

NOTE: DEF is commonly used to describe a diesel exhaust fluid such as AdBlue®. DEF is also used to describe an aqueous urea solution scale for measuring diesel exhaust fluids such as AdBlue®. AdBlue® is a registered trademark of the VDA Verband der Automobilindustrie e.V.