I. Main Technical Parameters: Measuring Range and Minimum Scale: Sugar: 0-40% Minimum Scale: 0.2%; alcoholic acidity: 0-25%. Second, method of use: 1) Align the refracting prism with the direction of light, adjust the eyepiece aiming ring until the marker is clear; 2) Adjust the reference point: first prepare the standard solution (pure water), the instrument and the liquid to be measured at the same temperature before measurement. Lift the lid, then place 1-2 drops of standard solution on the refracting prism and gently press the lid with your hand to obtain a light and dark boundary line. Turn the calibration screw so that the light-dark boundary line in the eyepiece field of view coincides with the reference line (0%); Note: This optical instrument is factory calibrated and can be used directly. 3) Lift the lid, wipe the surface of the prism with a soft cloth, take 1~2 drops of the solution measured on the refraction prism, cover the lid and gently press, read the relative scale of the clear boundary line and dark, which is the concentration value and the density value of the measured liquid. 4) After measurement, wipe the surface of prism and cover plate with a damp washcloth and store the device properly after drying. Calibration The instrument requires zero point calibration before measurement. Take a few drops of distilled water, place them on the test prism and turn the zero adjustment screw so that the dividing line is adjusted to the 0% scale position. Then wipe the test prism and perform the test. Some types of instruments require a standard solution instead of distilled water for calibration. Caution This instrument is a precision optical instrument, and the following points should be considered when using and maintaining it: 1. When using, caution should be exercised, strict compliance with the use, not to arbitrarily loosen the instrument from the connecting parts, not to fall, not to collide, and not to experience violent vibration. 2) After use, it is strictly prohibited to put the instrument directly into water to clean it, and it should be wiped with a clean soft cloth. 3) The instrument should be stored in a dry, non-corrosive place. 4) Avoid the loss of spare parts. 4. Avoid the loss of spare parts. Third, the product application Refractometer has the advantages of simple and shockproof structure, easy operation and transportation, clear vision and low price. Sugar series are used in canning, juicing, brewing and fermentation, beverage, fruit, honey harvesting and other fields. The salt series are used in the field of seawater breeding, aquarium, saline preparation, etc. Medical series are used for the detection of serum protein and specific gravity of urine. Industrial series are used for detection of automotive battery fluid, freezing fluid, cleaning fluid, machine tool lubricating fluid and cutting fluid.