Refractive Index is a fundamental physical property that is used in conjunction with other properties to characterize pure hydrocarbons and their mixtures. It is a useful property for concentration measurements, purity determinations and chemical identification.
The Koehler Automatic Refractometer uses precision optics and superior image analysis to extend the repeatability and accuracy of refractive index measurements for petroleum products. Subjectivity is removed from tests results because no manual activities such as aligning shadowlines or reading analog scales are necessary. Opaque hydrocarbons present no problem for this unit which uses reflected light measurement technology as opposed to manual refractometers which are of the transmission type. The refractometer incorporates numerous innovations designed to improve the accuracy of petroleum product testing. A linear scanned diode array shadowline sensor is sensitive enough to read even the most demanding samples. A 589 nanometer filter gives true Sodium D-Line refractive index readings. A built-in twin Peltier heating and cooling system gives the instrument the capability of reading at up to 100°C without the need for an accessory water bath. The measuring system guides the operator through every step of the process, advising if enough sample has be used and if it’s placed correctly, providing information about the cleaning process and if residue has been left behind. Set-up, diagnostic and calibration routines are displayed with easy to follow step-by-step instructions. User-developed customer calibration curves may be programmed allowing automatic temperature correction, direct percent concentration, percent reaction completion, etc. This unit has been used successfully throughout the petrochemical industry.
Conforms to the Specifications of:
ASTM D1218, D1747, D5006, D5775
Measurement Scales: Refractive Index (RI), BRIX (% sucrose), Temperature Corrected RI, Temperature Corrected BRIX, Ten User-Programmable Scales
Illumination: 589nm light emitting diode with interference filter (estimated life: 100,000 hrs)
Range: Dissolved Solids: 0 to 95% solids
Refractive Index: 1.26000 to 1.72000nD (nD – Sodium D-Line Refractive Index)
Readability: 0.01% Solids 0.00001nD
Precision: Refractive Index Standard Oils ± 0.00002 – Typical clear aqueous samples, % Solids Temperature Compensated, as sucrose ±0.02%
Calibration Fluid: refractive index standard oil, NIST traceable nominal value 1.495 RI, 67.61 BRIX
Sample Types: Transparent, translucent or opaque
Prism Assembly: Stainless steel, synthetic sapphire sealed with solvent-resistant epoxy
Calibration: 1 point – Water only; 2 point – Water and refractive index or Brix standard