FAQ (Frequently asked questions) are regularly occuring questions with regard to our products which we would like to answer in written form further below.
In addition, our supplier Atago Co. Ltd. has an extensive list of explanatory websites as part of their refractometer offering online. After successful registration you can access their FAQ, too.
| Refractometers | |
| Instruction manual for the hand-refractometer | Wine making: Why does the difference occur between hydrometer and refractometer results? |
| What is the refraction index? | |
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My prism clap at the refractometer is broken. Can I replace it myself? |
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Can I measure the sugar content in wine with a refractometer? |
What else do I have to consider when changing the prism claps? |
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How to calibrate the refractometer and how does the temperature compensation work? |
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| Generating of a Saccharose-Water-Solution (for example 20,0 %) | How to determine the concentration of cooling lubricants with a refractometer? |
| How to calibrate the refractometer? | How to perform the temperature - correction? |
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Alkohol measurement of beer distillates with the differential-refraktometer DD-7 |
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| Hydrometers | |
| Hydrometer - when measuring in water - doesn't show show the amount of Oechsle. | Hydrometer instruction manual |
Wine making: Why does the difference occur between hydrometer and refractometer results?
The measurement of the weight of the must and the degree of Oechsle can be performed in several ways, for example with hydrometers and refractometers. The weight of the must is the figure, which indicates how much gram/liter a must is heavier than a liter water at 20°C. The weight of the must therefore is a density meter. A properly measuring density measurement system is the reference system.
A refractometer, also an officially calibrated, is - according to our opinion - not a reference measurement system, because it does not directly measure the density. One has to consider that, for the comparison of measurement results of a refractometer and a hydrometer, no sugar-/water solutions shall be used, but must has to be used.
A certain - ideal - acidity relationship in this must has to be set as given. If this acidity relationship changes - with same sugar content - then the result of the refractometer changes as well, because the acids do have great influence on the refractometer measurement. The results of the hydrometers - in contrast - do not get affected by different levels of acidity. Primarily therefore the differences between refractometric and hydrometric measurements of the must do occur.
Brix (=%mas) is the saccharose part of a 100 g heavy saccharose-water-solution. Normally, saccharose is being called "sugar". The underlying formula was developed by ICUMSA on the basis of the refractive index ( nD).
My prism clap at the refractometer is broken. Can I replace it myself?
The clap of the prism can be exchanged. Many different types of prism caps do exist. Therefore, it is very important - when ordering a new one - that you do inform us about the model that you have, and when you have bought your refractometer. The current refractometers are models of the E-series. In the following you can find pictures of some prisms.
How to fix the prism claps at the refractometer?
The claps of the E-Serie, for example the N 1-E have to be fixed with splints (No. 3). The claps of the predecessor series with nuts and screws.
What else do I have to consider when changing the prism claps?
Be careful that the clap (No. 4) can be closed without gap. If this is not the case please remove the prism holder (No. 1). The prism holder can be removed by opening the screws (No. 2) on the right and left of the calibration screw; then the prism holder can easily be removed horizontally.
Can I measure the sugar content in wine with a refractometer?
The measurement value depends on all diluted chemicals. In Wine there are - besides saccharose - also alcohol and acids. The measurement value is being influenced by these chemicals. The sugar content therefore can not be measured directly.
The scale of the refractometer can not be read anymore due to water drops/humidity within the refractometer. What can be done?
Water came into your refractometer. Heat up your device slowly with a fan up to 50 °C. If this does not bring any success, then please send in your refractometer. Our service technicians will be able to repair it - in most cases.
How to calibrate the refractometer and how does the temperature compensation work?
| Cailbration | Sort of the temperature compensation | |
| N-1 α N-8 α N-10 E N-20 E N-50 E H-50 Typ 500 |
Measure pure water. Note the value of the temperature compensation thermometer. Remove the scale according to the value of the temperature compensation thermometer. |
In-built temperature compensation thermometer |
| N-2 E | With saturated salt solution. | Integrated temperature compensation thermometer |
| N-3 E N-4 E |
With the calibration liquid Standard Liquid LB. | Integrated temperature compensation thermometer |
| H-80 | With the calibration liquid Standard Liquid LF. | |
| ATC-1 E ATC-20 E |
Measure the water and fix the border line onto 0 %Brix. | Automatic temp.compensation on 20 °C |
| ATC-2 E | Measure a 30 % saccharose-water-solution and put the border line onto 30 %Brix. | Automatic temp.compensation on 20 °C |
| Honey | Calibration liquid "Kübler". | Automatic temp.compensation |
How to perform the temperature - correction?
Refractometer measure proper results at +20 °C. Since the measurement temperature has great influence on the result, refraktometric measurement results, measured at a different temperature, have to be corrected. Individual correction data can be read directly at the prism with most refractometers. According to each stand of the temperature display, the correction values have to be added to or substracted from each measurement result. An additional correction table is not required anymore.
Example:
When looking at the occular it is obvious, that the border line for the measurement of water is crossing the scale at 1 % Brix. The correction value +1 % can be read at the prism clap (at the end of the display liquid, similar to a thermometer).
The corrected measurement result is -1 % + 1 %= 0.
Simple rule for the temperature correction of refractometers with refractive index scales: 0,0001 up to 0,0004 nD per °C at fermentation temperatures below 20 ° have to be substracted, at higher temperatures they have to be added to the measurement results. Since the effect of the temperature on the refractive index is different with each different medium/solution, the individual correction value has to be taken from specialised books/literature. This does also apply to all measurements with refractometers which are solely equipped with a thermometer.
Automatic temperature correcting refractometers can undertake the temperature correction automatically (in principal between +10 and +30 °C).
How to calibrate the refractometer?
Upon delivery the refractometers are calibrated properly. Nevertheless, the refractometer has to be checked regularly. Particularly heavy shocks can cause damage and de-calibration. Herefore simply measure water - in the optimal case distillated water. The measurement temperature (in particularly the fermentation temperature) has to be 20°C exactly. Then the measurement result has to be 0 %Brix (with Art.-No. R 2895 =,,water line"). Is the measurement result not equal to 0, then the border line has to be adjusted by turning the calibration screw.
Refractometers for medicine as well as Art.-No. R 2350 have the adjusteable measurement result of 1,3330 nD, because this is the refractive index value of pure water at 20 °C.
The Art.-No. R 2121 and R 2630 have to be calibrated with the help of saturated cooking salt solutions.
(as much cooking salt in water as possible, until the salt does not dilute anymore); measure like explained. The measurement value at a measurement temperature of 20 °C is 29,6 % Brix (= salt mark at R 2630).
For the calibration of the Art.-No. R 2131, R 2141 and R 2611 Leo Kübler GmbH can supply a buffer solution with defined Brix- and nD-Wert (at a slightly higher price). This calibration liquid is being measured with a refractometer. Thereby the refractometer must have a temperature (measurement temperature) of approx. 20 °C. In case the refractometer does not show the required value, then the borderline has to be adjusted via the screw and with the help of a screw driver until the screw and the display reaches the (required) "starting position" value. The buffer solution can be removed with soft paper and alcohol/detergents such as soap from the prism and from the backside of the prism (water alone is not sufficient in most cases). R2912 requires a return to the manufacturer for after-calibration