Hanna Instruments HI96822 Digital Refractometer for Seawater Analysis
The robust, portable HI96822 digital refractometer is designed to measure the salinity of fresh or salt water. The HI96822 typically reports data in Practical Salinity Units (PSU), salinity in parts per thousands (ppt), and specific gravity (S.G. (20/20)).
The instrument’s high level of accuracy and simplicity of use result in reliable readings every time. All values are displayed with a 1.5 second reaction time, and they are all temperature-adjusted automatically. Both the sealed flint glass prism and the stainless steel well are easy to clean. To prepare for the next sample, simply clean with a soft towel.
- Sample size as small as 2 metric drops (100 μl)
- Sealed stainless steel well with high-grade optical prism made of flint glass
- Fast 1.5 second response time for temperature compensated readings
Description
By measuring the refractive index to ascertain the salinity of both natural and artificial seawater, including brackish, ocean water, or saltwater aquariums, the HI96822 Digital Refractometer reduces the ambiguity inherent with mechanical refractometers. The device transforms a sample’s refractive index into PSU, ppt, and specific gravity. The physical characteristics of saltwater were used in these conversions, which were based on reputable scientific articles (not sodium chloride). The HI96822 is a simple-to-use instrument for determining the salinity of natural and synthetic seawater, whether in a lab, field setting, or at home.
- Designed for seawater salinity analysis (not NaCl)
- Automatic Temperature Compensation
- High accuracy measurements displayed as PSU, ppt and specific gravity
Making a Standard Solution
Sodium Chloride solutions can be used to check the accuracy of the meter. The table below lists two Sodium Chloride solutions and their expected ppt Seawater value.
To make a Standard NaCl Solution (g/100 g), follow the procedure below
- Place container (such as a glass vial or dropper bottle that has a cover) on an analytical balance.
- Tare the balance.
- To make an X NaCl solution weigh out X grams of high purity dried Sodium Chloride (CAS #: 7647-14-5: MW 58.44) directly into the container.
- Add distilled or deionized water to the beaker so the total weight of the solution is 100g.
Example Standard NaCl solution:
| NaCl (g) | Water (g) | Total | Expected Seawater value (ppt) | |
| 3.5% NaCl | 3.50 | 96.50 | 100.000 | 34 |
| 10% NaCl | 10.00 | 90.00 | 100.000 | 96 |
Refractive Index
The refractive index of a sample is used by the HI96822 to obtain measurements. The refractive index gauges the behavior of light as it travels through the sample. Light will refract and reflect differently depending on the makeup of the sample. The refractive index of the sample can be examined by measuring this activity with a linear image sensor and utilized to ascertain its physical characteristics, such as concentration and density. The HI96822 enables measurement through the employment of an LED light, prism, and lens in addition to a linear image sensor.
Refractometry values will be impacted by temperature variations, hence temperature correction should always be used for accurate findings. The refractive index is converted to PSU (Practical Salinity Units), ppt (part per thousand), or S.G. (20/20) using specialized algorithms that are programmed into the HI96822, which has an integrated temperature sensor. The conductivity ratio of seawater to a typical KCl solution is known as PSU. The efforts of the UNESCO, ICES, SCOR, and IAPSO served as its foundation. The Joint Panel of Oceanographic Tables and Standards has this information published. A more traditional scale for measuring salinity is the ppt (10-3), where salinity is defined as “the weight of the inorganic salts contained in 1 kilogram of saltwater assuming all bromide and iodide are replaced by an equivalent quantity of oxides” (Knudsen, 1901). Based on the established correlation between density at 20 °C and the mass of dissolved salts in the saltwater sample, specific gravity (20/20) was developed (CRC Handbook of Chemistry and Physics, 87th Edition).
Features at-a-glance:
One-point calibration
- Calibrate with distilled or deionized water
Small sample size
- Sample size can be as small as 2 metric drops (100 μl)
Automatic Temperature Compensation (ATC)
- Samples automatically compensated for temperature variations
Quick, accurate results
- Readings are displayed in approximately 1.5 seconds
Dual-level LCD
- The dual-level LCD displays measurement and temperature readings simultaneously
Stainless steel sample well
- Easy to clean and corrosion-resistant
Battery indicators
- Battery percent level remaining at startup and low battery indicator
Automatic shut-off
- To conserve battery life the meter shuts off automatically after three minutes of non-use
IP65 water resistant protection
- Water resistant ABS plastic casing designed to perform under laboratory and field conditions.
| SKU | HI96822 |
|---|---|
| Product Name | Digital Refractometer for Seawater Analysis – HI96822 |
| Quote Required | Yes |
| Salinity (PSU) Range | 0 to 50 PSU |
| Salinity (PSU) Resolution | 1 PSU |
| Salinity (PSU) Accuracy | ±2 PSU |
| Salinity Range | 0 to 150 ppt |
| Salinity Resolution (ppt) | 1 ppt |
| Salinity Accuracy (ppt) | ±2 ppt |
| Specific Gravity Range | 1.000 to 1.114 Specific Gravity (20/20) |
| Specific Gravity Resolution | 0.001 Specific Gravity (20/20) |
| Specific Gravity Accuracy | ±0.002 Specific Gravity (20/20) |
| Temperature Range | 0 to 80°C (32 to 176°F) |
| Temperature Resolution | 0.1°C (0.1°F) |
| Temperature Accuracy | ±0.3 °C (±0.5 °F) |
| Temperature Compensation | automatic between 0 and 40°C (32 to 104°F) |
| Automatic Shut-Off | after three minutes of inactivity |
| Battery Type/Life | 9V / approximately 5000 readings |
| Dimensions | 192 x 102 x 67 mm (7.6 x 4.01 x 2.6”) |
| Weight | 420 g (14.8 oz.) |
| Refractometer Light Source | yellow LED |
| Minimum Sample Volume | 100 μL (to cover prism totally) |
| Sample Cell | stainless steel ring and flint glass prism |
| Measurement Time | approximately 1.5 seconds |
| Ordering Information | HI96822 is supplied with battery and instruction manual |
| Notes | Enclosure Rating |
