Digital refractometers measure the refractive index of a gel, liquid or solid sample to in order to determine the sample’s concentration. Since more concentrated samples bend light at a larger angle, digital refractometers operate by illuminating the sample against a prism and digitally measuring the angle of refracted light with photodiode detectors. Digital refractometers are used to measure a variety of substances, from the concentration of sugar in grape juice to the purity of solvents, and are widely employed in production and quality control applications in the food, chemicals and pharmaceutical industries. Digital refractometers may be designed for manual, semi-automatic or fully automatic sample reading. Compared to an analog instrument, a digital refractometer offers quick and extensive selection between measurement units and easily exports results. The upper and lower reading limits vary significantly between digital refractometer models. Temperature-controlled digital refractometers, for ranges up to 10 to 120°C, provide better accuracy by compensating for the changes in a sample’s refractive index caused by heat or cold. Handheld digital refractometers offer convenience but may be less accurate and require larger sample sizes compared to desktop instruments. Some digital refractometer models are designed for specific applications with more limited capabilities but optimized performance.
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| Company | Rudolph Research Analytical | Rudolph Research Analytical | Rudolph Research Analytical | Rudolph Research Analytical | Rudolph Research Analytical |
| Item | J157 PLUS Bench Automatic Refractometer | J357 High Performance Automatic Refractometer | J457 Automatic Refractometer | J57HA Automatic Refractometer for Food Quality Testing | J57WR Bench Automatic Refractometer for Chemical QA |
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| Catalog Number | Inquire | Inquire | J457-SC / J457-FC / J457-WC | Inquire | Inquire |
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| Description | The Rudolph J157 model of Refractometers offers high performance and a range of features to suit many demanding applications in laboratories and harsh industrial environments. Rudolph Research Analytical, working together with refractometer (Refraktometer) users from various countries and The Rudolph J157 model of Refractometers offers high performance and a range of features to suit many demanding applications in laboratories and harsh industrial environments. Rudolph Research Analytical, working together with refractometer (Refraktometer) users from various countries and disciplines, has developed the J157 series of Digital Refractometers. The Rudolph J157 bench-top line combines the features, measurement range, and accuracy that meet the most demanding applications both in and out of the laboratory and shares many features with the Rudolph Research Refractometer Product Line.... Read More | Designed as a research quality instrument the J357 has the highest performance of any refractometer in the Rudolph range. This instrument offers the same extra wide range as our chemical industry models combined with the high accuracy of our food industry models. It also offeres the most powerful Designed as a research quality instrument the J357 has the highest performance of any refractometer in the Rudolph range. This instrument offers the same extra wide range as our chemical industry models combined with the high accuracy of our food industry models. It also offeres the most powerful temperature control and is able tot measure at up to 120 °C
Operation: Operating the J357 is as simple as placing a sample on the artificial sapphire prism, closing the presser and reading the answer -- all in just a few seconds. There are no shadow lines to match and there is no eyepiece requiring any kind of operator determination or manual adjustment. When the "measure when stable mode" is selected, the J357 automatically waits until the sample has been heated or cooled to a predefined temperature before initiating a measurement.
Dual Electronic Temperature Control to 120C: Unlike other temperature controlled refractometers, the J357 has temperature D6control from both above and below the sample. The sample cover is controlled to the same temperature as the prism and, when lowered, is designed to provide a temperature controlled micro environment that provides unr+D18ivaled temperature stability, fast measurement time and minimal evaporation. With he Auto Measure option, the sample cover can also be used to initiate measurement.... Read More | All J457's come with Smart Measure™ Technology that automatically detects when the prism is improperly cleaned, insufficient sample is loaded, or if the instrument is improperly calibrated.
Exclusive Dual Temperature Control System
All J457 models come with Rudolph's exclusive Dual All J457's come with Smart Measure™ Technology that automatically detects when the prism is improperly cleaned, insufficient sample is loaded, or if the instrument is improperly calibrated.
Exclusive Dual Temperature Control System
All J457 models come with Rudolph's exclusive Dual Temperature Control System utilizing Peltier Technology. The J457 heats and cools the sample from both prism surface and sample cover. The insulating cover housing seals the Prism Well Ring to create a uniform temperature environment providing unmatched temperature control uniformity
Features - Dirty prism detection
- Incorrect calibration detection
- Insufficient sample load detection
- Cross contamination detection
- Improper water zero detection
- Trapped air bubble on prism surface detection
... Read More | The J57HA was designed to meet the unique needs of food quality testing where the refractometer is viewed as a QC tool rather than a laboratory instrument. A single flat measurement surface, electronic temperature control and one button measurement capability make it perfect for heavy use The J57HA was designed to meet the unique needs of food quality testing where the refractometer is viewed as a QC tool rather than a laboratory instrument. A single flat measurement surface, electronic temperature control and one button measurement capability make it perfect for heavy use applications.
Automatic Measuring System: The Rudolph J57HA features a fully automatic measuring system. The operator simply places the sample on the prism, presses a button and the result is displayed on 7.5cm x 10cm back lit LCD. There are no shadow lines to match and there is no eyepiece requiring operator determination or manual adjustment.
Electronic Temperature Control: Brix readings are very sensitive to temperature changes. However these changes in BRIX readings can be minimized by using the ICUMSA temperature correction for sucrose, but only minimized, not eliminated. The ICUMSA Temperature Correction Table was developed for a sucrose and water solution and the further from pure sucrose and water the sample is, the more inaccurate Temperature Correction becomes. Temperature Correction also requires that the sample temperature remain stable during the measurement. So a room temperature sugar solution measurement works reasonably well, but if a sauce sample comes from a kettle or a refrigerator, temperature correction will be almost useless. The solution to measuring hot samples has always been to control the sample temperature with a circulating water bath and then clean and maintain the water bath. The J57HA’s built in electronic temperature control provides the best solution for these real world problems: absolute accuracy regardless of sample type and excellent thermo stability no matter what the sample or environmental temperatures are.
High Accuracy: The J57HA was designed for the food industry with a BRIX range of 0 - 95% and a Refractive Index range of 1.33 - 1.53 RI. The J57HA has a ±0.03 BRIX and ±0.00004 Refractive Index accuracy, which matches the accuracy of Rudolph’s best refractometers.... Read More | The J57WR Automatic Refractometer was designed to meet the unique needs of industrial environments in the chemical industry where the refractometer is viewed as a QC tool rather than a laboratory instrument. A single flat measurement surface, electronic temperature control and one button measurementThe J57WR Automatic Refractometer was designed to meet the unique needs of industrial environments in the chemical industry where the refractometer is viewed as a QC tool rather than a laboratory instrument. A single flat measurement surface, electronic temperature control and one button measurement capability make it perfect for heavy use applications.
Automatic Measuring System: The Rudolph J57WR features a fully automatic measuring system. The operator simply places the sample on the prism, presses a button and the result is displayed on a 7.5cm x 10cm back lit LCD. There are no shadow lines to match and there is no eyepiece requiring operator determination or manual adjustment.
Electronic Temperature Control: Refractive Index (BRIX) readings are very sensitive to temperature. When measuring sucrose users have the option of correcting for temperature variation but that option does not work for most chemical companies. Users not measuring sucrose or users looking for better accuracy than provided by temperature correction had to spend the extra money for a circulating water bath and then clean and maintain it. The J57WR’s built in electronic temperature control provides the best of both worlds, the absolute accuracy, regardless of sample type, of a temperature controlled instrument with the convenience of operating without a water bath.
Wide Measuring Range: The J57WR was designed for chemical measurement, not food. This means a very wide measurement range from 1.26 - 1.70 enabling the instrument to measure materials like fluorocarbons and aromatic chemicals that are beyond the range of most refractometers.... Read More |
| Refractive Index Range | 1.33 - 1.53 RI | 1.26 - 1.72 RI | 1.26 to 1.72 RI | 1.33 - 1.53 RI | 1.30 - 1.70 RI |
| Brix Range | 0 - 100 BRIX | 0 - 100 BRIX | 0 to 100 BRIX | 0 - 100 BRIX | 0 - 100 BRIX |
| Resolution | ±0.00001 RI (or ±0.01 BRIX) | ±0.00001 RI (or ±0.001 BRIX) | ±0.00001 RI (or 0.001 BRIX) | ±0.00001 RI (or ±0.01 BRIX) | ±0.0001 RI (or ±0.01 BRIX) |
| Temperature Range | 4°C to 95°C | 10°C to 100°C (±10°C Optional) | 10°C to 110°C | 10°C to 65°C | 10°C to 65°C |
| Optical Wavelength | 589.3 nm | 589.3 nm | 589.3 nm | 589.3 nm | 589.3 nm |
| Measuring Time | < 3 seconds (User configuarble) | < 2 seconds | < 30 seconds (User configurable) | < 5 seconds (User configuarble) | < 5 seconds (User configuarble) |
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