What does a hydrometer measure in physics? How to use a hydrometer to measure the density of an electrolyte? Features of assessing the electrolyte level in a battery

The performance of the entire car depends on the quality of the car battery. To check whether it is performing its functions correctly, measuring the density of the electrolyte in the battery is often sufficient. For this there is such a tool as a car hydrometer. In this article we will tell you how to use a hydrometer, what the principle of their operation is based on, what they are based on their operating principle, and also answer other questions that users of this useful device may have.

How does this meter work?

The operating principle of a hydrometer is simple. Everything is based on the well-known Archimedes law.

It looks like this: a transparent flask with a pear at the end. A float is placed inside the structure.

It is recommended to start measuring 2 hours after charging the battery. Each jar is checked separately. You need to take in as much liquid as necessary to lift float The result is marked onscale that is marked on the flask. Normal - within 1.27-1.29 g/cm 3 . It is noteworthy that indicators at different banks may differ.

How to read a hydrometer reading? The scale directly marks the values ​​corresponding to the immersion up to this division. Part of the extension of the floating hydrometer is above the surface. The value of the division on the appendix means the density of the liquid in which it is immersed.

Kinds

Hydrometers are either mechanical or digital (electronic). The mechanical one was described above, but the electronic one looks like a small rectangular or round device with an antenna sensor that must be immersed in for measurement.

Many people ask how densimeters differ from hydrometers. In fact, nothing. This different names of the same object, the purpose of which is to measure density.

Why do you need a hydrometer?

A motorist first of all needs a densimeter for electrolyte and antifreeze. The characteristics of these two fluids play a decisive role in the functioning of the car. From electrolyte to battery depends on how much it is able to restore charge.

If you know, you can carry out its maintenance yourself. If it is less than normal (1.28 g/cm3 at room temperature), then the battery needs to be charged, in some cases this helps.

Or it could be an indicator of other problems:

• incorrect chemical reactions due to sulfitation ;
• high degree of wear (for example, in case of generator failure);
• obsolescence;
• the battery was of poor quality from the very beginning.

In many similar cases the battery will have to be replaced.

If the temperature differs from 25°C, then refer to a special table, which can be easily found in the relevant literature, to determine what density is normal under such conditions.

Measuring the electrolyte in a battery with a hydrometer

To keep your battery in working condition, you need to understand how to use a hydrometer correctly. A conventional automobile hydrometer, in addition to a glass float vessel, includes a “bulb”, a glass flask-tube for taking a sample and a stopper for the flask.

The electrolyte for testing is drawn into the tube. To do this, place the float in the tube, close it with a stopper with a tip on one side and a bulb on the other. The pipette is immersed in the acid and required quantity typed using a pear. The float should float freely when positioned vertically.

Where the scale touches the liquid, you need to read the value.

After use, be sure to rinse the entire instrument to extend its useful life and avoid errors in subsequent measurements.

Small safety instructions: Use protective gloves and goggles that are resistant to aggressive environments. Remember that even a small drop of acid that gets on the body will lead to extremely unpleasant consequences. Ordinary clothes will be ruined by the same drop. Follow safety rules when starting to work with sulfuric acid or other aggressive substances.

Hydrometer for electrolyte and antifreeze

There are similar meters for antifreeze or antifreeze (which are practically the same thing). They may be required to understand whether the cooler has lost its frost resistance, as well as whether the purchased coolant is of high quality. Insufficient density indicates that the antifreeze needs to be replaced. Densimeters for antifreeze are usually equipped with a scale that changes color depending on the suitability of the coolant for use.

If it's green, everything is fine. Partial or complete loss of frost resistance is indicated by a red, yellow or blue mark.

Many antifreeze hydrometers today have a freeze point meter built into them. It is easy to learn what the operating principle of such a hydrometer is based on, so that you can later easily check the density and temperature yourself.

They say there are people who made a hydrometer themselves?

Yes, and we can tell you how to make a household hydrometer with your own hands at home.

It can be made from a syringe or a pen housing. To weigh it down you will need something like nuts. Nuts are screwed onto the syringe to provide weight so that it floats vertically but does not sink. The readings of such a home device are determined by immersing a syringe in a liquid of known density. It is recommended to use water, as well as liquid with highest density, what you are going to measure, provided that it has already been defined. Then it will be possible to line the surface of the syringe in divisions.

Your device may not have a typical hydrometric scale, the main thing is that you will know whether the characteristics of the measured electrolyte or antifreeze differ from normal or not. Those who have ever used a hydrometer made by themselves confirm that the density is measured quite accurately, as far as is necessary for Maintenance car.

The most important thing is not to forget that a densimeter made with my own hands, may be unsafe when used with sulfuric acid or similar materials.

It doesn't matter whether you bought a battery hydrometer at a store or made one yourself. The main thing is to regularly use it to check the automotive fluids listed above so that the technical condition of your car is always in good condition. Keep your instrument clean and you can always count on correct readings that will protect you from breakdowns and low-quality materials.

Surely every car owner has encountered the problem of poor starting. vehicle V winter time. There may be several reasons for this. But in most cases, the battery is considered the culprit. The fact is that key characteristic its performance is determined by the density of the electrolyte. The battery charge, its voltage and the quality of engine starting depend on this parameter. It is recommended to periodically check the density of this liquid. For this, a special measuring tool is used. In today's article we will look at what a hydrometer is, and also learn how to correctly measure the density of electrolyte in the battery and antifreeze in the cooling system. This information will be useful to every car owner.

Characteristic

So what is a hydrometer? This is an instrument that is used to measure the density of solids and liquids. The operating principle of the hydrometer is based on Archimedes' law. Externally, this device is a glass flask, the lower part of which is filled with shot to obtain the desired mass.

At the top (in the narrow part of the tube) there is a scale. It is calibrated according to the density of the solution. On this moment There are two types of hydrometers - constant mass and constant volume.

How it works?

This device operates thanks to a special float. It is he who determines the exact density of the liquid. How to use a battery hydrometer? Note that you need to start taking measurements only at room temperature. You need to collect fluid from each “can,” of which there are six in a car battery (including those on trucks). Next, the float will automatically rise and show the current density of the measured liquid.

How to read readings? For this purpose, a special scale is provided with values ​​that correspond to immersion to a specific division. Part of the float will be above the surface. The value of the division on the appendage will determine the current density of the electrolyte.

Kinds

Today there are several types of data measuring devices:

• Mechanical hydrometer.
• Electronic.

The first type is a round flask with a float inside. In digital, the scheme is somewhat different. An electronic hydrometer is a kind of probe with a metal end. There is a digital display at the top. This device runs on regular batteries thanks to sensors. However, such devices are in little demand on the market due to their high cost. The mechanical analogue costs 10-15 times less, and therefore is used most often.

Why is it so important to monitor density?

We have already found out what a hydrometer is. At first glance, it may seem that this device is not needed. But it is precisely this that allows you to notice a low level of density in time and prevent serious consequences. If we talk about antifreeze, it can freeze at sub-zero temperatures. As you know, coolant, which contains a lot of water, expands when it freezes. As a result, the pipes burst and the radiator is deformed. Naturally, it is impossible to continue driving in such a car.

If we talk about the battery, with a low electrolyte density, such a battery is not able to quickly restore its charge. As a result, the battery voltage is always below normal - 11.0–11.5 volts. When starting the engine, the starter takes another 2 volts, which leads to deep discharge of the battery. All this significantly reduces battery life. This is why it is important to know how to use a hydrometer. Below we will look at how to take measurements.

We take measurements on the battery

Let's look at how to use a battery hydrometer. To do this, it is necessary to provide access to AKB banks. The covers can be unscrewed with a thick slotted screwdriver. Next, we immerse the glass flask-tube inside and take out some of the liquid using a bulb. The float should float freely and be vertical. How to find out the result? The density level is considered to be the place where the scale comes into contact with the electrolyte. Having measured the data on one bank, we move on to the next. Please note that after the measurements, the pumped-out electrolyte is returned to the jar from which it was taken.

Safety precautions

Before checking the density of the electrolyte with a hydrometer, you should wear rubber gloves. It is also important to protect the sleeves, since this liquid is very aggressive. If electrolyte gets on your skin, immediately rinse the affected area under running water.

This liquid has an aggressive effect not only on the skin, but also on clothing. It is better to use things made of thick fabric, since the electrolyte can partially corrode them. Be careful not to get liquid into your eyes. Safety glasses are a good idea.

How to level up?

The ideal result is a density of 1.27 grams per cubic centimeter. If this parameter is 1.23 and below, the density urgently needs to be increased. How to do it? To do this, you should purchase an electrolyte (it is available at any car store). If the density is extremely low (less than 1.18 grams per cubic centimeter), it is better to completely pour out the electrolyte present in the battery, then rinse the insides with distilled water. Work should be carried out with rubber gloves, otherwise serious burns are possible.

After this, we pour new electrolyte into each of the cans until it completely covers the surface of the plates. It is desirable that its level be 1.0–1.5 centimeters higher than the lead plates. Next, put the battery on charge. The charger must be set to low current. Without tightening the lids, wait until some of the liquid boils away. After a couple of hours, remove the battery from charging. After waiting another hour, we take a measurement. The density should be between 1.27 and 1.29 grams per cubic centimeter.

Hydrometer for antifreeze

You can also find similar coolant meters in stores. They operate on the same principle, based on Archimedes' law. How to use such a hydrometer? The instructions are practically no different from measuring the density of the electrolyte.

So we need to unscrew the lid expansion tank and take some liquid from there. It should fill at least half the volume of the flask. Next we will notice how the float begins to rise up. The place where it comes into contact with the liquid will be our result. The ideal value is 1.07 or 1.10 grams per cubic centimeter. In this case, the freezing point of the liquid will be -40 degrees Celsius. If the value is close to one, crystallization will occur earlier - down to zero degrees.

Also note that some models have a scale that changes its color depending on the suitability of the antifreeze for use. So, the green scale indicates that the liquid is suitable for winter period. Partial or complete loss of frost resistance is determined by a yellow or red scale.

How to restore the density of antifreeze?

Here the technology is slightly different. To prevent antifreeze from freezing at sub-zero temperatures, concentrate should be added to it. It usually has a crystallization temperature of -80 degrees and is sold in liter bottles. Often one eggplant is enough to shift the freezing threshold by 10-15 degrees. After adding the required amount of liquid, you can safely begin operation.

About the cost

If we talk about mechanical products, their cost varies from 140 to 320 rubles. The cost of digital ones starts from 5 thousand rubles.

Note that devices are strictly divided by area of ​​application. There are hydrometers for electrolyte and antifreeze on sale.

Conclusion

So, we found out what a hydrometer is and how to use it. As you can see, it's quite useful thing, which will be useful to every car owner. It is worth having two hydrometers available - for antifreeze and for electrolyte. It is recommended to measure the density of the battery at least once a year. As for the coolant, you need to check it only after mixing it with distilled water (when the antifreeze level was previously low). It is worth remembering that the higher the percentage of water in the coolant, the lower its crystallization threshold.

Vladimir Khomutko

Reading time: 3 minutes

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Operating principle of a hydrometer for petroleum products

Density is one of the most important characteristics products such as oil and its derivatives. The instruments used to measure this parameter will be discussed in this article.

A hydrometer for petroleum products is glass device, which is used to measure density only liquid substances. This option is for solids it cannot be measured using a hydrometer, although many are mistaken about this.

The operating principle of this measuring instrument is quite simple. It is based on Archimedes' law, and we will talk about this in more detail below.

Such devices are made only from transparent glass, since there must be a void inside in which a graduated scale with divisions marked on it is clearly visible. The device itself consists of two tubes of different diameters hermetically sealed together, made of glass. The ends of these tubes are also sealed (soldered).

This is due to the fact that the hydrometer must have a constant weight throughout its entire service life, which ensures the accuracy of the measurements. The narrow top tube has a white scale, usually made of paper. This scale is graduated, and the graduation itself directly depends on the purpose for which the device is used.

Hydrometers are calibrated in both absolute (g/cm) and relative (%) values. Bottom part The device is filled with ballast, which is a small metal shot. The choice of such ballast is due to the fact that with the help of small pellets it is easier to control the weight.

Briefly and simply, the operating principle of such devices is as follows.

Everyone knows that the densities of different liquids are not the same. For example, the value of this parameter for gasoline is lower than the same value for water on the surface of which it floats. So, if you first lower the float into water, and then place the same float in gasoline, you can see that it will sink into them to different depths.

Hydrometers for petroleum products

When conducting laboratory measurements Graduated hydrometers for petroleum products are used as such a “float”. Since their design provides for the presence of a scale with divisions in the upper part, the position of the liquid on this scale will show the value of the desired indicator of the liquid product under study.

In addition to hydrometers, this indicator can be measured with densimeters. The operating principle of these measuring instruments is the same, but the former can also measure temperature, while the latter cannot.

The number of devices of this type offered on the market is quite large, and the choice depends on the scope of their application. For example, ANT-1 and ANT-2 devices are widely used for work at gas stations. It is at gas stations that staff constantly receive petroleum products, so strict control over the quality and quantity of fuel received is necessary. Both can be done using this device.

For example, the mass of fuel in a tank, knowing its exact volume, can be easily calculated from its density.

Knowing the temperature at which measurements are taken is also important, since petroleum products, like other physical bodies, compress with decreasing temperature, which increases the density value.

Hydrometer ANT-2

Such measuring devices are required in all laboratories of many industrial sectors, and make it possible to control the quality indicators of petroleum products and other liquid substances with high accuracy.

1. Purpose and general information

1.1. A hydrometer for electrolyte, antifreeze, antifreeze and washer fluid with a built-in thermometer complete with a device for collecting liquid (a set for a motorist) is designed for selecting and measuring the density of the electrolyte in the battery ( Fig.1), determining the freezing temperature of the coolant in the engine cooling system (Fig.2) and the freezing temperature of the washer fluid in the car windshield and headlight washing system ( Fig.3), as well as for measuring the temperature of the test liquids (electrolyte, antifreeze, antifreeze, washer fluid).

1.2. As an electrolyte in car batteries Aqueous solutions of sulfuric acid are used.
1.3. Coolants and washer fluids belong to the antifreeze group. Antifreezes are frost-resistant liquids that freeze at temperatures below zero degrees Celsius (°C) and differ in the basis of their preparation and scope of application.
1.4. Coolants are antifreezes made from ethylene glycol and propylene glycol. Antifreeze is a brand of antifreeze based on ethylene glycol.
1.5. Washer fluids (washers) are antifreezes made on the basis monohydric alcohols: methyl, ethyl and others.
Washers based on methyl alcohol - methanol, as washer fluids, are prohibited for use in many countries (they have a negative effect on vision, motor and nervous systems).
Mix antifreezes made in on different basis, Not recommended.

2. Delivery set

2.1. Hydrometer with built-in thermometer AETOTr: 1 pc.;
2.2. The device for collecting fluid (electrolyte, coolant and washer fluid) consists of:
- pipette: 1 piece;
- pear: 1 piece;
- plug with tip: 1 piece;
2.3. Passport: 1 pc.;
2.4. Packaging case: 1 pc. (the lid of the pencil case is made and used as a watering can (funnel)).

3.Design and technical characteristics

3.1. A hydrometer for electrolyte, antifreeze and washer fluid with a built-in thermometer AETOTr TU U 33.2-24667973-004:2007 is a glass float, in the upper part of which a paper hydrometer scale is placed, and in the lower part there is a thermometer built-in. The hydrometer scale consists of three main scales - scale electrolyte, antifreeze, washer (Fig.4).

3.2. Scale electrolyte graduated in density units g/cm3
- electrolyte density measurement range: from 1.10 to 1.30 g/cm3
- scale division price: 0.01 g/cm3
- permissible error limit: 0.01 g/cm3.
3.2.1. The colored bars on the electrolyte scale indicate the percentage (%) of battery charge:
- yellow bar - battery is low,
- red - charged 50%,
- blue - 75%,
- green - 100% charging.
3.3. Scale antifreeze consists of two scales (one located on the left, the other on the right), graduated in degrees Celsius with a minus sign (-° C) and designed to determine the freezing temperature of coolants.
3.3.1. The scale on the left is designed to determine the freezing point of the coolant based on ethylene glycol:
- range for determining the freezing temperature of the coolant: from 0 to minus 40 ° C;
- scale division price: 5° C.
3.3.2. The scale on the right is designed to determine the freezing point of the coolant based on propylene glycol:
- range for determining the freezing temperature of the coolant: from 0 to minus 30 ° C;
- scale division price: 5° C.
3.4. Scale washer consists of two scales (one located on the left, the other on the right), graduated in degrees Celsius with a minus sign (-°C) and designed to determine the freezing temperature of washer fluids.
3.4.1. The scale on the left is designed to determine the freezing temperature of washer fluid made from ethyl alcohol- ethanol:
- detection range for washer fluid freezing: from 0 to minus 40°C;
- scale division value: 5°C.
Washers made on the basis of ethyl alcohol - ethanol can be recognized by the flame icon on the packaging.
3.4.2. The CIS market is supplied with washer fluids whose density differs from the density of liquids made on the basis of ethyl alcohol - ethanol. Having studied the densities and freezing temperatures of these liquids, we constructed an average scale for them, highlighting in color the ranges of possible freezing of these liquids:
- yellow- the washer fluid freezes to minus 20°C;
- red - freezes at minus 20°C;
- green - below minus 20°C.
3.5. The scale of the built-in thermometer is calibrated in degrees Celsius (°C) and is designed to determine the temperature of the liquid being tested, which allows for corrections to the hydrometer readings (Table 1) to be taken into account if the liquid temperature differs from 20±2°C:
- temperature measurement range of the test liquid: from minus 40 to plus 40°C;
- scale division value: 5°C.

Table 1

4. Operation of the device

4.1. Before starting work, it is necessary to assemble the liquid sampling device, as shown in Fig.5.

4.2. Squeeze the bulb and lower the tip of the plug into the liquid being measured. Slowly unclenching the bulb, allow the liquid to fill the pipette in such an amount that the hydrometer floats freely in a vertical position. When reading readings from the hydrometer scale, the level and line of contact of the liquid with the hydrometer rod should be below the pipette corrugation (Fig. 6), and the hydrometer rod inside the corrugation. Point contact of the hydrometer rod to the inner corrugation of the pipette prevents continuous sticking of the hydrometer to the pipette wall.

4.3. The line of contact of the liquid with the hydrometer rod corresponds to:
- on a scale electrolyte- electrolyte density;
- on a scale antifreeze- freezing temperature of the coolant;
- on a scale washer- freezing temperature of the washer fluid.
Readings are taken according to bottom edge meniscus Measurements should be made at a temperature of 20±2°C.
4.4. If measurements are made at a liquid temperature different from 20±2°C, then the correction given in Table 1 should be added algebraically (that is, with its sign) to the measurement results.
The amendments in Table 1 for coolant and washer fluids are given for their optimal concentrations corresponding to the freezing point of these fluids at minus 40 °C. Coolant corrections highlighted in red are for reference only because when low temperatures liquid, the correction is so large that the freezing temperature value on the hydrometer scale will go beyond the measurement limits of the device. For coolants, we recommend taking measurements at temperatures of plus 10°C and above.
4.5. After taking measurements, the hydrometer and liquid sampling device must be washed clean water and wipe dry.

Good to know

Optimal electrolyte density in the battery depending on the time of year and area of ​​operation

table 2

Electrolyte freezing point depending on density

Table 3

5. Warranty

5.1. A hydrometer for electrolyte and antifreeze AET with a device for collecting liquid (a set for a motorist) is manufactured in accordance with TU U 33.2-24667973-004:2007.
5.2. Guarantee period operation 12 months from the date of sale through a retail network.

A hydrometer is a measuring apparatus used in various laboratories for measuring density and specific gravity bodies, as well as liquids. This device is also used to determine the concentration of substances in solutions consisting of two components.

The principle of operation of this device is based on Archimedes’ law, known to any physicist (any physical body, being in water, weighs the same as the weight of the water displaced by this body). The hydrometer has the form of a glass float filled with ballast, usually of metallic origin. Exist as hydrometers general purpose, and special hydrometers for petroleum products (kerosene, gasoline, diesel fuel), for electrolyte, for alcohol, for milk, whey and other liquids. With their help, the density of a particular liquid is determined, as well as the strength of a particular alcoholic drink.

To measure the conditional weight of a liquid, it is carefully poured into a glass vessel, into which the hydrometer is then carefully lowered. When the device is in the correct position, readings are taken on the scale. The weight value is taken to be the indicator opposite which the liquid level is recorded.

When working with a hydrometer, the laboratory assistant also uses a bucket with a lid. It is needed as a reservoir for working water, into which our device with the solution is immersed. The purpose of the lid is to collect a sample of the test solution.

The components of a hydrometer are a float, a measuring cup, a rod that has a main and correction scale, and a removable sinker. It turns out that without chemical glassware not enough. The measuring cup has 2 cavities - one serves to sample the solution being measured, the other to accommodate ballast, which is most often made of metal, necessary to ensure the stability of the device lowered into water. From environment The ballast is insulated with a polyethylene plug.

A car hydrometer has a special design - inside the glass tube of such a device there is not 1 float, but a certain number. Their mass is different, but the volume is completely similar. All floats have a number corresponding to a specific density. When the tube is filled with liquid, some of the floats float, some do not. If, of all the floats that float, take the one on which it is written greatest number, then it is he who shows true density test liquid.

The price of hydrometers is low; a set of hydrometers or a separate copy can be purchased at laboratory equipment stores.

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