Hydrometer is based on the law of Archimedes and objects floating on the surface of the balance of the conditions made of liquid density is an instrument. Concentration of acid at a standard temperature of 25 degree to measure the specific gravity (density) of the liquid.
With a closed glass tube, one end of uniform thickness, the inner wall attached to the scale paper, the other end of a slightly bulky bubble-like, the bubble with small lead tablets or mercury, the glass tube can be detected in the liquid vertical immersion To a sufficient depth, and can be stably floated in the liquid, that is, when it is subject to any shaking, can automatically restore to a vertical rest position. When the hydrometer is floating in a liquid, its gravity is equal to the gravity of the liquid it drains. So in different liquids immersed in different depths, the pressure is different, hydrometer is the use of this relationship scale.
Baume (° Bé) is a method of expressing the concentration of a solution. The Baume hydrometer immersed in the measured solution, the degree is called Baume degree. Baume degrees to the French chemist Baume (Antoine Baume) named. Baume is a pharmacy apprentice origin, former Paris School of Medicine professor. He created the hydrometer – Baume hydrometer. There are two kinds of Baume hydrometer: one is called heavy table, used to measure the liquid than the weight of water; the other called the light table, used to measure the liquid than light water. After measuring the Baume degree, from the corresponding chemical manual of the table can be easily found in the percentage of the concentration of the solution. For example, at 15 degree measured concentration of sulfuric acid Baume degrees is 66 ° Bé, look-up table shows that the mass percentage of sulfuric acid concentration is 98%. The specific gravity of the general hydrometer can be converted to Baume’s degree by the following formula. In the formula, D1 represents the specific gravity of the liquid heavier than water (numerically equal to its density) and D2 represents the specific gravity of the liquid lighter than water. Baume degree value is large, easy to read, so in the production of commonly used Baume degree that the concentration of the solution (a certain concentration of the solution has a certain density or specific gravity).
Measure the depth of the liquid than the length of the hydrometer, so that the hydrometer suspended in the liquid, the horizontal plane and the scale of the degree of intersection is the liquid concentration. If you do not have a liquid container it is recommended to buy a measuring cylinder for easy measurement.
The use of densitometer is very extensive. Heavy water, for the determination of various acid, alkali, salt aqueous solution density, such as acid sulfuric acid, nitric acid, hydrochloric acid and some inorganic or organic acids and so on.
Lighter than water, for the determination of methanol, ethanol, ether and other solutions, as well as gasoline, kerosene, vegetable oil, petroleum ether and other liquids density.
1. the first should be based on the measured liquid density and accuracy of floating gauge and clear the standard temperature and sub-value.
2. the floating gauge should be carefully cleaned, when the float after cleaning into the liquid, the only hand to get in the tube above the highest groove parts, and pay attention to the vertical pick and place.
3. filled Sheng liquid experience of life containers (glass tube or graduated cylinder and the like) washed and then slowly poured into the liquid, and continue to observe the mixing without bubbles, and then into the floating meter. Float into the liquid after the entry part (including the main pipe and the liquid surface contact part) shall not have bubbles, if there should be raised float liquid surface to exclude bubbles.
4. the floating gauge into the liquid, the trunk should be measured in the measured line up and down within the three sub-degree mobile, eye view meniscus is normal, if not normal should re-wash the floating meter.
5. readings, the floating device shall not be with the solvent wall, bottom and stirrer contact, according to the provisions of the reading method to read the value of the float.
6. in the floating meter readings before the determination of liquid temperature, and take their arithmetic mean as the temperature of the liquid, and then according to the formula on the floating indicator value for temperature correction.
7. if required for capillary constant correction, the formula should be carried out on the floating value of capillary correction.
8. a floating cycle of the test cycle to be sent to the relevant measurement department on time to ensure that the accuracy of the instrument.
Total length is about 250mm.
The diameter of tube with iron sand at the end is 13mm and length is 25mm.
The diameter of middle small transparent tube is 5mm and length is 55mm
The diameter of middle big transparent tube is 12mm and length is 50mm.
The dimaeter of graduated glass tube at the top is 7mm and length is 120mm.