This document is an instruction manual for the HI 96821 refractometer for sodium chloride measurements. The document provides information on the preliminary examination of the instrument, technical specifications, principle of operation, functional description, display elements, measurement guidelines, calibration procedure, measurement procedure, unit and temperature conversion, preparation of standard sodium chloride solution, battery replacement, warranty, and error messages.
The HI 96821 is a rugged, portable, and water-resistant optical instrument designed to measure sodium chloride concentration in aqueous solutions. It utilizes an LED light source and an image sensor to determine the refractive index, which is then converted to concentration units such as g/100 g, g/100 ml, Specific Gravity, or °Baumé. The device features Automatic Temperature Compensation (ATC) and a large dual-level LCD display.
| Measurement Range (g/100 g) | 0 to 28 |
|---|---|
| Resolution (g/100 g) | 0.1 |
| Accuracy (g/100 g) | +0.2 |
| Temperature Compensation | Automatic between 10 and 40 °C |
| Minimum Sample Volume | 100 µl |
| Battery Life | 5000 readings |
| Enclosure Rating | IP 65 |
| Dimensions | 19.2(W) x 10.2(D) x 6.7(H) cm |
The instrument requires a minimum sample volume of 100 µl to cover the prism totally.
Calibration should be performed daily, before measurements, when the battery is replaced, or between long series of measurements.
If the temperature exceeds 10-40 °C, the 'ATC' tag blinks and automatic temperature compensation is disabled.