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About refractometers

  • What was refractometer?

  • How does a refractometer work?

  • What are refractometers used for?

  • How is the measurement process carried out?

  • Which refractometers are available from Conrad?

  • FAQ – frequently asked questions about refractometers

 

What was refractometer?

A refractometer is a measuring device based on the optical principle of refraction. The names of the devices are derived from Latin, from "re" for "back" and "French" for "break". The German scientist Ernst Abbe (1840 to 1905), who developed the basics of modern optics, made a significant contribution to the development of these devices. A device of this category carries the name "Abbe" in the Conrad shop.

 

How does a refractometer work?

The refractive index is measured in the refractometer . For this purpose, the behavior of light is compared, on the one hand at a prism with known optical properties and on the other at the transition at the substance to be tested. The light spreads at the two transitions to be compared with different angles. The refractive index of the sample medium is measured by the deflection of light. The following measuring principles are used: Transmitted light, striking incident or total reflection .

The temperature has a large influence on the refractive index. Therefore, the temperature of the prism and the sample must be regulated or included in the calculation. Some of the devices offered by Conrad have auto temperature compensation (abbreviation ATC); in other models, the measured value must be calculated by means of a table to the standard value of 20 degrees Celsius.

If the general composition of a liquid is known, a refractometer may be used to determine the concentration of the substances dissolved in the liquid. For example, the sugar content of wine or sugar beet is determined.

 

What are refractometers used for?

The range of possible uses of a refractometer is large. Examples are the control of lubricants, the testing of beverages, fruit, fruits and sweets in the food industry, the determination of the degree of maturity of fruits during harvest, honey production, wine and fruit production, the associated wine, must and alcohol production, as well as the doping control or frost protection control in motor vehicles

Refractometers have partly assured protection types (IP) to enable their use in certain requirements.

 
 

How is the measurement process carried out?

Refractometers are usually supplied with a calibration fluid that is used to prepare the instrument for use. After calibration according to the operating instructions, the medium to be evaluated is drips onto the measuring prism. The refraction is output as a relatively sharp-edged light-dark transition on a scale in the transmitted-light display. For refractometers for special applications, the industry-typical measured value is offered as a scale, for example Grad Oechsle in the wine growing sector or Grad Baumé in the confectionery industry.

Digital devices evaluate the optical ratios with a measurement electronics and output numerical values on displays.

 

Which refractometers are available from Conrad?

High-quality analogueue and digital refractometers from different manufacturers are available in a large price range in the Conrad shop for business customers. Another selection feature is calibration.

For refractometers, there are detailed operating instructions and data sheets that provide exact statements on all technical parameters, included accessories and available measuring modes. These documents are available for download from the respective product in the Conrad shop. 

 

FAQ – frequently asked questions about refractometers

What was to be observed when using refractometers?

  • Refractometers are precision optical instruments and should be handled with care. Touching the optical surface with bare fingers should be avoided.
  • Before use, check that the prism and the cover flap on the unit are clean.
  • Make sure that the device has been calibrated before taking measurements.
  • Calibrated refractometers may be required for certain applications. The term currently used for calibration is "conformity assessment" – official verification of the accuracy of, among other things, measuring tools in accordance with the law of measurement and weight. For some of the devices at Conrad, calibration can be ordered with to carry out measurements that require calibration.
  • Be very careful when handling dangerous liquids to be measured, for example when testing car battery acid or antifreeze for car coolers. Many of these substances are harmful to health and must not come into contact with eyes and skin.
  • When handling the AdBlue fuel additive, absolute cleanliness must be ensured. Even the smallest impurities can damage the AdBlue system and thus lead to its failure. In addition, the following applies: Long storage and high temperatures slowly decompose AdBlue. In the event of a positive test result from AdBlue, certain criteria must be met (see operating instructions). Shifts indicate its decomposition.
  • Do not use metallic objects such as needles, spoons or tweezers to apply substances to be measured. There is a risk that the measuring prism will be scratched. We recommend the use of plastic pipettes for transport and application of the solutions.
  • Clean a refractometer thoroughly after each use and store it in the designated transport container.
  • Do not open Refractometers. Otherwise, the guarantee will expire, just as in case of improper use.

How long does a refractometer last?

The service life of purely optical refractometers is theoretically unlimited if the device is not damaged by mechanical effects. For digital devices, the battery life is sufficient for approximately 10,000 measurements.

How can ich recognize a defective refractometer?

  • Implausible measured values indicate a faulty calibration.
  • Poor visibility of the shadow line due to dirty or scratched optics
  • In most cases, a missing indicator on the display indicates that the power supply is not working.
  • Due to dirt and mechanical wear, the threads of the optical eyepiece adjustment can become stiff or immovable.
 
This text is machine translated. About refractometers What was refractometer? How does a refractometer work? What are refractometers used for? How is the measurement process carried out? Which refractometers are available fr...