The HI96831 is a rugged, portable digital refractometer designed for the measurement of percent volume and freezing point of ethylene glycol based solutions. The HI96831 has a high accuracy of ±0.2% volume and ±0.5 °C freezing point and features simple operation that gives reliable results each and every time. All readings are automatically compensated for temperature variations and displayed within a 1.5 second response time. The sealed flint glass prism and stainless steel well are easy to clean. Just wipe with a soft cloth in preparation for the next sample.
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The HI96831 Digital Refractometer utilizes the measurement of refractive index to determine the percent volume and freezing points of ethylene glycol based solutions. Ethylene glycol is used in glycol cooling systems for industrial applications. Maintaining the appropriate percent of glycol is important in glycol chillers as too low of a percentage could lead to the system freezing and rupturing while too much glycol will reduce the systems efficiency. The instrument converts the refractive index of a sample to percent volume or freezing point. These conversions are based on internationally recognized references for unit conversion and temperature compensation for glycol solutions (e.g. CRC Handbook of Chemistry and Physics, 87th Edition). The HI96831 is an easy-to-use tool for measuring freezing point and percent volume in ethylene glycol solutions, in the field or in the lab.
To make an Ethylene Glycol Solution, follow the procedure below:
The HI96831 takes measurements based on a sample’s refractive index. Refractive index is a measurement of how light behaves as it passes through the sample. Depending on the sample’s composition, light will refract and reflect differently. By measuring this activity with a linear image sensor, the sample’s refractive index can be assessed and used to determine its physical properties such as concentration and density. In addition to the linear image sensor, the HI96831 uses an LED light, prism and lens to make measurement possible.
Variations in temperature will affect the density of a solution based on the compound that is present. In digital refractometry the use of temperature compensation is necessary for accurate results. The HI96831 contains a built-in temperature sensor and is programmed with temperature compensation algorithms in accordance with the ICUMSA Methods Book for a percent by weight sucrose solution.
Freezing point is displayed as a temperature from 0.0 to -50.0 °C corresponding to 0-58 % by volume. The display blinks the freezing point when the concentration of Ethylene glycol is greater than 78 % concentration by volume. When the display shows “LO”, the freezing point is at a minimum (below -50 °C).
0 to 100%
0 to -50°C
±0.5 °C (±0.5 °F)
0 to 80°C (32 to 176°F)
±0.3 °C (±0.5 °F)
automatic between 10 and 40°C (50 to 104°F)
Minimum Sample Volume
100 μL (to cover prism totally)
stainless steel ring and flint glass prism
approximately 1.5 seconds
9V / approximately 5000 readings
after three minutes of inactivity
Refractometer Light Source
192 x 102 x 67 mm (7.6 x 4.01 x 2.6”)
420 g (14.8 oz.)
HI96831 is supplied with battery and instruction manual