What are electronic scales for? Modern scales: types of scales

Scales are used in many spheres of life. There are many types of these devices, differing in parameters, characteristics and design. The modern range of devices is diverse. But in order to choose the right scales, you need to familiarize yourself with their types.

Definition

What is a scale? This is a device that allows you to determine the mass of an object. Usually products, parcels, building materials are weighed. Each device has its own purpose, so it may differ from others. The first weights are considered to be the lever ones. Their appearance and the weighing method could be different, but the principle is the same.

The most famous are the cup. The product is placed in the container, and the reference weight is placed on the other side. By balancing, it was possible to set the mass. Now they are producing different types scales. Each of them is used in a specific industry, therefore, differ in characteristics.

Mechanical

By the mechanism, devices are mechanical, electromechanical and electronic. The first function with a lever system and weights. Mechanical scales are considered very easy to use. The information is shown by an arrow that is associated with a leverage system.

Mechanical scales are the most popular. Their advantage is considered to be their low cost. But such devices need competent maintenance, because without the lack of lubrication, cleaning and adjustment, the device will not work normally.

Electromechanical

The weighing procedure on such devices is performed due to the interaction of the leverage system with the weights. Weight will be shown electronic device... The advantages of the instruments are that they are easy to read, but the mechanical elements deteriorate quickly. And device recovery is not that easy.

Electronic

Electronic scales are considered the most modern and convenient to use. The devices have an unusual weighing mechanism: the sensor signals the load to the indicator. If you follow the rules of use, then the device will serve for many years.

The main requirement is to comply with the weighing restrictions, that is, do not exceed the weight. Otherwise, the sensor breaks down. Among the advantages of the devices are the ease of weighing, reliability. The device allows you to calculate the amount based on the price and weight of the cargo. Electronic scales are the most resistant to mechanical stress and platform displacement. But there are also disadvantages - the high price of the sensor and the difficulty of replacing it.

Trade

What is a trading scale? These are the devices necessary for the sale of goods. Scales for weighing products will help you to trade competently. The following types of devices are used for this activity:

• packing;
• commodity;
• for counter trade;
• for self-service shops;
• scales with label printing.

Such devices have displays, the number of which can be up to 6 pieces. They are placed either on the body or on a separate rack. These types of scales are multifunctional, have Beautiful design... With them, calculations are performed quickly.

Types of trade scales

All types of trade scales include a two-sided display so that the seller and the buyer can see the weight of the goods. These devices are among the most popular. There are the following types:

• counters calculate the value of the item when the price per kilogram is entered;
• scales are also produced for self-service stores, which mark goods and print receipts with the indicated value and weight;
• packing scales are used in shops, catering organizations when packing goods;
• commodity scales for a warehouse - large devices that allow weighing goods within 60 kg - 2 tons;
• scales with label printing function: used in self-service stores.

Postage

For execution postal work scales are also needed. The device allows for accurate measurements, as it is required for weighing parcels, parcels, letters. The best are considered electronic options, which have a high cost. But they have many advantages:

• board, which indicates the weight of the product
• function of selection of discreteness and limits;
• protective properties;
• self-diagnosis system;
• connection to a computer.

There are scales for light and small loads. The equipment allows you to determine grams to accuracy. There are devices for large goods as well.

Industrial

What is an industrial scale? These are devices used by logistics companies, post offices, manufacturing enterprises to measure goods. Appliances are placed on the floor as they are large. They are designed for weighing goods in various fields.

By modifications, they are divided into mobile, shockproof, moisture and dustproof. No less popular are wagon, crane, monorail, truck scales. Each device is designed for weighing large items.

Crane

What is crane scales? These are devices that allow you to change suspended loads. Such devices are used in the ports of cities, at metal depots, freight stations and at industrial organizations.

Crane scales can differ in weighing accuracy, type of lifting device, installation method. The devices are designed for loads from 1 to 10 tons. Devices are divided into mechanical and electronic. The latter types are considered the most accurate, then many enterprises use mechanical equipment.

Automotive

The devices are designed for weighing machines. They are used in ferrous and non-ferrous metallurgy, food and chemical industries. Also, without them, you can not work in agriculture and construction.

Depending on the weighing option, the scales change the machine at full arrival. These systems are built without foundations. There are devices for determining the weight of individual parts of the transport, and then the results are added. There are portable truck scales that are light in weight, low in price and dimensions, allowing them to be installed in any place.

Pallet

This type of scale is used for goods on pallets. These priors are used in warehouses and logistics enterprises. The equipment is compact in size, but it weighs large loads.

For convenience, there is an electronic display that allows you to adjust the control. The lifting device is a platform equipped with 4 sensors. Pallet scales have other functions as well.

Appliances

Various scales are also produced for the household sphere. They differ in design, principle of operation and quality. Some have a weighing pan to make the weighing process more convenient. They are used for free-flowing, watery products. In this case, additional capacity is not required.

Devices with a platform are necessary for measuring loads of various parameters. In everyday life, mechanical and electrical scales are used. Devices are in demand to determine the mass of a person. They are customized up to 300 kg. Some types of equipment have the function of a body fat analyzer. There are diagnostic scales.

Medical

There are types of special devices required for the medical field. They are floor-standing, as well as mechanical and electronic. The first ones work on the basis of a measuring spring. The equipment cannot show the exact weight, therefore, its error is taken into account.

Electronic devices are of different types:

• simple ones with a digital display and a mechanical device;
• devices with high measurement accuracy.

Medical devices include devices used for weighing children, so they are in hospitals, clinics, maternity hospitals. They are compact, have a special shape for comfortable placement of a child, as well as a display. Medical scales with a stadiometer allow you to determine the weight and height of a person.

Laboratory

In laboratory conditions, weighing of substances is also necessary, therefore, special scales are used for this. Laboratory devices are in demand at enterprises, banks, jewelry workshops. Their advantage is the availability of additional functions. For example, hydrostatic weighing is carried out with them, which makes it possible to determine the density of liquids and solids.

Calibration is performed using an external weight or automatically. A feature of the devices is the presence of several units of measurement. Professional equipment has many functions. Due to the variety of types, it is possible to choose the scales for specific purposes.

Jewelry

The jewelry business requires a quality balance that delivers accurate results. Now there are devices that should have a test pressure of no more than 0.01 grams. This norm means the error that can be during weighing. If the device does not comply with these rules, then it cannot be used.

According to the law, craftsmen must use only high-quality jewelry scales that meet all standards. They are used only in some areas. Allows an error of 1 gram, then this technique can be used to weigh scrap metal. Jewelry scales are necessary for measuring stones, but then the error is not calculated in carats.

When crystals are weighed in the range of 1000 - 4000 carats, there may be a deviation of 0.04 carats. Many modern appliances have windscreens that allow settings to be retained even when the weather changes. As an additional function, there can be a timer that records dates and other information about the measurement. The presence of memory will allow you to save data that can be transferred to a computer.

Features of the kitchen scale

What is a kitchen scale for? They are needed to determine if there was any fraud in the store. In some products with the original packaging, the weight is indicated incorrectly. This will determine which product to buy and where.

Thanks to the kitchen scale, it will be possible to prepare the dish according to the recipe, because the weighing of the components will be required. It is not so easy to determine the amount of ingredients by eye, but the device will be an assistant. Some kitchen scales also work according to foreign methods, so you can switch the change in them, for example, in pounds.

You need equipment if you want to follow a diet. The scale will help you control the amount of food you eat, as this is important for weight loss. There are functions for determining energy value, volume. Which device to choose depends on the purpose and desire.

Types of kitchen scales

It is advisable to purchase not mechanical, but electronic, since they allow you to more accurately determine the weight of products. The equipment can have a bowl of different shapes. The material of the bowl is different. Usually they are made of plastic, glass, steel. The first type is considered the best because it is lightweight and affordable material. The devices have different systems management. For the home, it is advisable to purchase scales without buttons. The shelf life of devices is usually set within 1 - 2 years.

When choosing a measuring device, it is necessary to pay attention to the characteristics. If additional functions are not needed, then you should not overpay. In this case, you can purchase a budget option scales. It is also important to consider the manufacturer and usability. A quality device cannot have a low cost.

Important characteristics

The device must be protected from moisture. This property will allow you to maintain the performance of the balance for a long time. The obligatory characteristic is the presence of the function of zeroing the scale. A convenient property is automatic shutdown devices. Even if the hostess forgot to turn it off, the scales will do it on their own.

It is necessary to choose equipment with rubberized feet, which will protect against slipping. If steel scales are great for other purposes, then plastic ones are needed for the kitchen. They are lightweight and easy to clean. The function of switching measures is useful to many housewives.

Instrument rules

Before use, you must read the instructions for the device. Place the balance on a level place for accurate results. Leveling uses a building level. During operation, the mechanism must be stable. If the setting is correct, the arrow is marked at zero.

The measuring mechanisms do not require any special care. It is enough to wipe them, and treat the parts with oil. Kitchen scales are also washed. Use the unit only for its intended purpose. It should not be stored or used in a room where there are flammable liquids and gases. Do not use the balance in areas with electromagnetic or electrostatic waves, as the results will be distorted. Disassembly and repair of equipment can only be performed by a master.

During the warranty period, the warranty card must be kept. It contains the date of purchase, the brand of the product, the seal of the store. If deficiencies are identified that have arisen due to the manufacturer, then the repair is carried out at the expense of the seller. The warranty does not apply if the defects appeared due to the user.

Spare parts for scales are bought in specialized stores. Manufacturers offer various parts: buttons, feet, indicators, stickers, sensors. These items will be required in case of repair of measuring equipment.

Balance classification and selection of accuracy class for testing.

scales- a universal device that is used to determine the mass of bulk and liquid substances, or objects. Weighing instruments have different requirements depending on the application. To determine the mass of products in the store, devices of a small accuracy class are used, and in testing laboratories and jewelry workshops, more accurate measuring instruments are needed.

Laboratory balance according to the principle of operation, they are divided into mechanical and electronic. About ten years ago, due to the release of GOST 24104-2001, mechanical laboratory scales were discontinued. The lengthy process of measuring the mass and non-compliance with the requirements of this GOST, led to the inappropriateness of the manufacture of such devices. Despite this, some laboratories continue to operate measuring equipment of the VLR brand, manufactured by Gosmetr. Determination of mass on equal-arm scales "VLR" is lengthy, therefore this brand is not used in express laboratories. In addition, measuring instruments electronic type easier to operate and have many useful features.

Balance classification according to accuracy class:

Analytical. This view laboratory equipment and instruments are used to determine the mass of an object with an accuracy of the fourth or fifth decimal place (1.2 accuracy class). Usually, the measurement error on an analytical balance is 0.0002 grams;

Scales of 3.4 accuracy class (third decimal place);

Technical ( middle class accuracy). Such laboratory equipment can measure mass with an accuracy of one tenth of a gram.

It makes no sense to purchase an analytical balance if the tests do not require high convergence and reproducibility. Most often, to find out the required accuracy of the determination, they use the normative documentation for the method of analysis. If the GOST or TU indicates the accuracy of taking a sample of up to one gram, this means that the technical scales of the brands "VK", "VLTE", "Sartorius" of the manufacturers "Massa-K", "Gosmetr" and "Sartogosm" are quite enough to measure the mass. ...

Scope of use of technical scales.

Technical scales used in the chemical, metallurgical, food industries, as well as in environmental laboratories. One of the advantages of this measuring technique is its versatility. Using this laboratory equipment and instruments, you can weigh hot substances, having previously installed a stand on the instrument platform. It is on such devices that the mass of hot baking sheets with coke is measured when determining the mass fraction of the total moisture of solid fuel. Technical scales are used to determine the mass of the test sample when testing the moisture content of soil, sand, slags, as well as when determining the granulometric composition of bulk materials.

Mettler and AXIS are foreign leaders in the manufacture of laboratory measuring equipment and instruments. Domestic laboratory scales have a low cost, and the quality is not inferior to foreign counterparts. Domestic manufacturers "Massa-K", "Sartogosm", "Gosmetr", produce a number of measuring instruments with weighing accuracy up to 0.1 grams, these include products of the brands "VK" and "VLTE".

For weighing in conditions of vibration and low air speed, the set of scales of the "Massa-K" company, brand "VK" has a windscreen. This minimizes the effect of wind on the measurement results. Measuring devices of the VL and VLTE brands are quite simple to operate, as they are equipped with a touch control panel. Removable cups and platforms are easy to clean, so even working with oil products and coal concentrates will not affect the operation of the scale. It is quite simple to prepare VLTE measuring equipment for operation. To do this, it is enough to center the instrument using the rotating feet and start the automatic calibration.

The scope of analytical balances.

Analytical balance- measuring laboratory equipment used to determine the mass of bulk or liquid reagents with very high accuracy. In no case should hot substances be weighed on such devices. An exception is a product manufactured by "Gosmetr" brand "VLR". In this case, the hot sample touches the cups of the apparatus and does not affect the accuracy of the method. The table on which the laboratory equipment is installed must be stationary and stable, since vibrations and vibrations increase the measurement error. To level the influence of air currents, the analytical balance has a glass chamber (showcase), inside which there is a bowl for taking measurements.

Scope of application of analytical balances:

In chemical laboratories. For taking a sample for the preparation of titration solutions;

In medical institutions. For weighing substances in the preparation of disinfectant solutions;

In production. When carrying out tests by gravimetric methods of analysis;

In environmental services. In order to control the purity of soil and water;

In food production test centers. In the process of testing to determine the acidity of bakery products and dairy products;

In jewelry workshops. For working with precious stones and metals;

In forensic services. To determine the degree of poisoning;

In narcological dispensaries. In order to confirm or deny the fact of intoxication.

Advantages of modern measuring instruments and their manufacturers.

Modern laboratory equipment and instruments are fully automated, therefore, calibration and adjustment are carried out with minimal operator involvement. Automatic tuning carried out by means of the built-in calibration weight, so even frequent movements of the instruments will not affect their operation. The most modern analytical balances are manufactured by a Russian-German joint venture, which has united the Russian "Sartogosm" and the German "Sartorius". Measuring devices "Sartorius" are equipped with a special interface that allows you to connect the device to a PC. This function is indispensable in the working environment of express laboratories, for maximum time savings. Now there is no need to record weighing results, because software remembers and stores data that you just need to print. Measuring devices "Sartorius" CPA 224S-0CE perfectly work in tandem with a sulfur and carbon analyzer. This allows you to enter the values ​​of the weights in special program, which independently calculates and provides the final results of sulfur and carbon values. The error introduced by the operator during the measurement process is minimal.

Scales can be useful in a wide variety of applications, from household to industrial. There are very different types of scales, and they differ not only in size, but also in functional characteristics and capabilities. Modern manufacturers offer the purchase of such devices different types, size, design and configuration, depending on the features of their operation and purpose.

Mechanical

Depending on the type of weighing mechanism, all scales are divided into electronic ones. The former work on the basis of interaction and loads, while the information is displayed by an arrow mechanically connected to a system of levers. In fact, these are traditional and familiar scales. This type of scale attracts attention with its low price. But such devices require competent maintenance, since such devices cannot be done without lubrication, cleaning and adjustment operations.

Electromechanical

The weighing process in such scales is carried out by the interaction of a system of levers with weights, while information about the load is displayed using an electronic device. Such devices are good for their ease of reading, but the mechanical parts of the equipment wear out quickly. In addition, the repair of such scales is not easy.

Electronic

These are the most modern and easy-to-use scales. Types of scales of this type have a special weighing mechanism - based on a sensor that gives a signal about the load to the indicator. If you follow the rules of operation, such scales can serve for a very long time. The main requirement is to comply with weighing restrictions, that is, do not exceed the specified weight. Otherwise, the sensor may be damaged.

Among the advantages of such devices are ease of weighing, reliability and the ability to calculate the amount, taking into account the price and weight of the goods automatically. Compared to the models described above, electronic ones have better resistance to mechanical factors and platform displacement. But there are also disadvantages, which are expressed in the high cost of the sensor and the difficulties of replacing it.

For trade

There are at least 5 types of weights that are used in trade. These include:

• packing;
• commodity (for a warehouse);
• for counter trade;
• for self-service shops;
• scales with label printing.

The peculiarity of commercial scales is their equipping with displays, which can be up to 6 pieces. They are located either on the body or on a separate outrigger stand. Such scales are multifunctional, have a well-thought-out design and allow you to carry out calculations as clearly and competently as possible.

Types of trade scales

Any trade scales have a two-sided display so that both the seller and the buyer can see the parameters of the goods being weighed. This is perhaps the most numerous scales according to the classification. The types of weights for trading are as follows:

• Counter devices calculate the cost of the goods after entering the data on the price per kilogram, add up the cost of several purchases, and calculate the change.

• For self-service stores, special scales are offered that can mark goods and print receipts (they print a label on which information about the product is displayed - its cost per kilogram, the final cost for the quantity of the weighed product, expiration dates).
• Filling scales are widely used in shops, catering establishments, when packing of piece goods is carried out. Most of the models are types of electronic scales that can be used in the industrial field (when packing hardware), pharmacies. Such equipment can have special protection against dust and moisture or double-sided weight indication.
• Warehouse scales are the most massive devices capable of weighing goods weighing from 60 kg to 2 tons. They are placed on the floor, and their usable area is related to the maximum weighing limit.
• Scales with label printing function: widely used in self-service stores. These devices are equipped with a thermal printer that prints self-adhesive labels. They indicate all the characteristics of the goods necessary for the consumer.

Postage

Postal scales differ in measurement accuracy, as they are associated with determining the weight of a parcel, parcel post or letter. The most functional are electronic models that are more expensive. But they have numerous advantages:

• a board that displays the weight of the postal product;
• possibility of automatic selection of discreteness and limits;
• good level of protective properties;
• built-in self-diagnosis system;
• the ability to connect to a computer.

You can choose mail scales for both light and small shipments, and for large-sized goods.

Industrial

There are various types of scales that are widely used in industry. So, platform devices are specific devices that are used by logistics companies, mail, manufacturing enterprises. All industrial scales are floor-mounted and bulky. They are specially designed to weigh loads in a variety of industries. Depending on the modifications, they can be mobile, shockproof, moisture and dustproof.

Scales such as wagon, crane, monorail, and automobile scales are no less popular in industry. All of them are distinguished by their massive structure and large platform area, designed for weighing bulky goods.

Crane scales

Types, types of industrial equipment pleases with a variety. For example, a crane scale is a measuring device that measures the weight of a suspended load. The use of such equipment is advisable in the ports of cities, at metal depots, freight stations and industrial enterprises. Crane scales are distinguished by their weighing accuracy, load receptor (bucket, hopper), installation method (mobile, suspended), and the way of achieving balance. By the volume of the measured load, the crane models are designed for a weight from 1 to 10 tons.

Such scales are mechanical and electronic. More accurate and promising latest models, although many enterprises are still equipped with mechanical equipment.

Automotive

These precision instruments are designed for weighing vehicles and road trains. It is advisable to use such scales in ferrous and non-ferrous metallurgy, food and chemical industries, agriculture and construction. Depending on the weighing method, the vehicle scales measure when the vehicle is fully driven. Such systems are built without foundations. Some models are designed to weigh the individual axles of the vehicle, after which the figures are counted together.

Separately, it should be said about portable vehicle scales. They are distinguished by their low weight, low cost and well-thought-out dimensions, which makes it possible to install them for weighing on any area.

Pallet

This type of scale is designed for weighing loads on pallets. Such devices are widely used in warehouse and logistics facilities. These innovative designs are compact but are used for weighing large loads. Most often, models are equipped with an electronic display, which makes it easier and more convenient to control the scales. The load receptor in such scales is a U-shaped platform with 4 sensors built into it. With ease of operation, the equipment is very reliable, since there are no moving parts. V standard version pallet scales have numerous additional functions.

Household options

Different types of scales can be used in everyday life, and they differ in a variety of designs and design solutions. Depending on the type of device, they are available with a weighing bowl or with a platform with removable stands. Conventional scales with a bowl are used for weighing loose, watery products, while the use of additional containers is not required. Devices with a platform are needed to measure loads or objects of different sizes.

The main types of scales that are used in everyday life are either mechanical or electrical. Devices that allow us to determine our weight are in particular demand. Such devices are designed for weight up to 300 kg. Some modern models can be supplemented with a body fat analyzer. Special attention deserved

In medicine

There are types of special scales that are used in the medical field. Such devices are always floor-standing mechanical or electronic. In mechanical structures, the main element of the weighing device is in the form of a measuring spring. Of course, there is no need to talk about a high level of accuracy of such scales, therefore, the error must be taken into account in the measurements. Electronic devices for medicine are produced in different types:

• simple - that is, with a digital display and mechanical filling;
• increased accuracy.

It is clear that in electronic scales it will still be much higher. The scales on which newborns are weighed in hospitals and clinics are also considered medical. Such models have compact dimensions, a special platform for placing the child and a display on which all the information necessary for the doctor is displayed.

For laboratories

Modern types of scales are highly accurate and allow measurements in various fields. Thus, laboratory devices are widely used not only in medicine, but also in laboratories of various enterprises, banks, and jewelry workshops. Their peculiarity is that they may have additional functions.

For example, they perform, that is, determine the density of liquids or solids, carry out dynamic weighing (measurement of non-static objects). Calibration in a laboratory balance is carried out with an external weight or automatic mode... A distinctive feature of such devices is the availability of several units of measurement. Moreover, professional and expensive models have an extended package of functions. Thus, it is possible to select scale models for specific purposes and functional features.

Scales (device) Scales, a device for determining the mass of bodies by the force of gravity acting on them. V. is also sometimes referred to as instruments for measuring other physical quantities that are converted for this purpose into force or at a moment of force. Such devices include, for example, current balance and Pendant scales. The sequence of actions in determining the mass of bodies in the east is considered in Art. Weighing.

V. is one of the most ancient instruments. They arose and improved with the development of trade, production and science. The simplest V. in the form of an equal-shoulder rocker with suspended cups ( rice. 1) were widely used in exchange trade in Ancient Babylon (2,500 BC) and Egypt (2,000 BC). Somewhat later, unequal-shoulder V. with a movable weight appeared (see. Steelyard). Already in the 4th century. BC NS. Aristotle gave a theory of such V. (rule moments of power). In the 12th century. the Arab scientist al-Khazini described V. with cups, the error of which did not exceed 0.1%. They were used to determine the density of various substances, which made it possible to recognize alloys, identify counterfeit coins, distinguish precious stones from counterfeit ones, etc. In 1586 G. Galileo to determine the density of bodies, he designed special hydrostatic voltages. The general theory of voltages was developed by L. Euler (1747).

The development of industry and transport led to the creation of V., designed for heavy loads. At the beginning of the 19th century. decimal values ​​were created ( rice. 2) (with the ratio of the mass of weights to the load 1:10 - Quintentz, 1818) and centesimal values ​​(V. Fairbanks, 1831). In the late 19th - early 20th centuries. With the development of continuous production, weighing machines appeared for continuous weighing (conveyor, metering, etc.). In various branches of agriculture, industry, and transport, vaults of a wide variety of designs have begun to be used for weighing specific types of products (in agriculture, for example, grain, root crops, eggs, etc.); in transport, automobiles, railways. cars, airplanes; in industry - from the smallest parts and assemblies in precision instrument making to multi-ton ingots in metallurgy). For scientific research, the designs of precise V. - analytical, microanalytical, assay, etc. have been developed.

Depending on the purpose, veneers are divided into exemplary (for checking weights), laboratory (including analytical), and general purpose, used in various fields of science, technology, and the national economy.

According to the principle of operation, V. are subdivided into lever, spring, electric tensometric, hydrostatic, and hydraulic.

The most common lever V., their action is based on the law of balance lever. The fulcrum of the lever ("rocker" B.) can be in the middle (equal-armed B.) or be offset relative to the middle (unequal and one-shoulder B.). Many lever V. (for example, commercial, automobile, portioned, etc.) are a combination of levers of the 1st and 2nd kind. The levers are usually supported by prisms and pillows made of special steels or hard stone (agate, corundum). On equal-arm lever V., the weighed body is balanced with weights, and some excess (usually by 0.05 - 0.1%) of the weight of the weights over the body weight (or vice versa) is compensated by the moment created by the rocker (with an arrow) due to the shift of its center of gravity relative to the original position ( rice. 3). The load compensated for by the shift in the center of gravity of the rocker arm is measured using a reading scale. The scale division value s of the lever V. is determined by the formula

s = k (P o c / lg),

where P 0 Is the weight of the rocker arm with an arrow, c is the distance between the center of gravity of the rocker arm and the axis of its rotation, l is the length of the rocker arm, g is the acceleration

free fall, k is a coefficient that depends only on the resolution of the reading device. The division price, and, consequently, the sensitivity of V., can be changed within certain limits (usually by moving a special weight that changes the distance c).

In a number of lever laboratory systems, part of the load being measured is compensated by the force of electromagnetic interaction — by drawing in an iron core connected to the rocker arm into a stationary solenoid. The strength of the current in the solenoid is regulated by an electronic device that brings the voltage to equilibrium. By measuring the current strength, the proportional load V. The center of gravity of the rocker arm is combined in these V. with the axis of rotation.

In laboratory practice, weights (especially analytical ones) with built-in weights for a part of the load or for a full load ( rice. 4). The principle of operation of such V. was proposed by D.I. Mendeleev. Weights of a special shape are suspended from the shoulder on which the load cup is located (single-arm V.), or (less often) on the opposite shoulder. In one-shoulder V. ( rice. 5) completely eliminates the error due to unequal balance of the rocker arm.

Modern laboratory V. (analytical, etc.) are equipped with a number of devices to increase the accuracy and speed of weighing: vibration damper for cups (air or magnetic), doors, when opened, there is almost no air flow, heat shields, mechanisms for applying and removing built-in weights, automatically operating mechanisms for the selection of built-in weights when balancing B. Projection scales are increasingly used, which make it possible to expand the measurement range along the reference scale at small angles of deflection of the rocker arm. All this makes it possible to significantly increase the speed of V.

In high-speed technical quadrant V. ( rice. 6) the measurement limit on the rocker deflection scale is 50 - 100% of the maximum load V., usually lying in the range of 20 g - 10 kg. This is achieved by a special design of a heavy rocker arm (quadrant), the center of gravity of which is located significantly below the axis of rotation.

Most types of metrological, exemplary, analytical, technical, trade ( rice. 7), medical, wagon, automobile V., as well as V. automatic and portioned.

Hooke's law is the basis of the action of spring and electric strain gauges. Hooke's law).

The sensitive element in spring voltages is a spiral flat or cylindrical spring that deforms under the action of body weight. V.'s readings are counted on a scale along which a pointer connected to a spring moves. It is assumed that after removing the load, the pointer returns to the zero position, that is, no residual deformations occur in the spring under the action of the load.

With the help of spring V., not mass is measured, but weight. However, in most cases, the scale of spring voltages is graduated in units of mass. Due to the dependence of the acceleration of gravity on the geographical latitude and altitude above sea level, the readings of spring-loaded V. depend on their location. In addition, the elastic properties of the spring are temperature dependent and change over time; all this reduces the accuracy of spring V.

In torsional (torsional) V., the sensitive element is an elastic thread or spiral springs ( rice. eight). The load is determined by the angle of twist of the spring thread, which is proportional to the torque generated by the load.

The action of electric strain gauges is based on the transformation of the deformation of elastic elements (columns, plates, rings), which perceive the force effect of a load, into a change in electrical resistance. The transducers are highly sensitive wire strain gauges, glued to elastic elements. As a rule, electric strain gauges (wagon, automobile, crane, etc.) are used for weighing large masses.

Hydrostatic V. is used mainly for determining the density of solids and liquids. Their action is based on Archimedes' law (see. Hydrostatic weighing).

Hydraulic V. are similar in design hydraulic press. Readout of readings is carried out using a pressure gauge, calibrated in mass units.

All types of V. are characterized by: 1) ultimate load - the highest static load that can withstand V. without violating their metrological characteristics; 2) by the price of division - by the mass corresponding to the change in the reading by one division of the scale; 3) the limit of the permissible error of weighing - the largest permissible difference between the result of one weighing and the actual mass of the body being weighed;

4) permissible variation in readings - the largest permissible difference in V.'s readings when repeatedly weighing the same body.

Weighing errors on V. of some types at maximum load.

Weighing error at full load

Metrological ...........

Exemplary 1st and 2nd digits

Exemplary 3rd category and

technical 1st class ............

Analytical, semi-microanalytical, microanalytical, assay

Medical ..............

Household .................

Automotive .............

Wagon ................

Torsional ..............

1 kg

20 kg - 1 kg

200 g - 2 g

20 kg - 1 kg

200 g ‒2 g

200 g

100 g

20 g

2 g

1 g

150 Kg

20 Kg

30 kg - 2 kg

50 t - 10 t

150 t - 50 t

1000 mg - 20 mg

5 mg - 0.5 mg

0.005 mg *

20 mg - 0.5 mg *

1.0 mg - 0.01 mg *

100 mg - 20 mg

10 mg - 0.4 mg

1.0 mg - 0.1 mg *

1.0 mg - 0.1 mg *

0.1 mg - 0.01 mg *

0.02 mg - 0.004 mg *

0.01 mg - 0.004 mg *

50 g

10 g

60 g ‒5 g

50 kg - 10 kg

150 kg - 50 kg

1.0 mg - 0.05 mg

0.01 mg 0.001 mg

* Using accurate weighing methods.

Lit .: Rudo N.M., Libra. Theory, device, adjustment and verification, M. - L., 1957; Malikov L.M., Smirnova N.A. 1, M. - L., 1962: Orlov S.P., Avdeev B.A., Weighing equipment of enterprises, M., 1962; Karpin EB, Calculation and design of weighing mechanisms and batchers, M., 1963; Gauzner S.I., Mikhailovsky S.S., Orlov V.V., Recording devices in automatic weighing processes, M., 1966.

N. A. Smirnova.

Great Soviet Encyclopedia. - M .: Soviet encyclopedia. 1969-1978 .

In laboratories of higher educational institutions and research institutes, as a rule, a large number of special equipment... It is required, firstly, for the practice of students and the implementation of normal procedures in research centers.

Secondly, it is an indicator of the technological level of the institution. The best universities in the country always have advanced equipment, such as, in particular, electronic laboratory scales, and in order to understand how important such equipment is for work, we will understand its purpose. The main value of laboratory balances is high precision. With their help, institutes measure the masses of samples of various substances and materials, usually weighing from 120 to 24000 grams.

The scope of the scales is those technological tasks and studies in which the exact weight is of paramount importance and therefore it is necessary to achieve the smallest error in its determination. And now it will be important to note who exactly uses modern laboratory scales everywhere.

Who uses a precision balance?

In general, any scales of high technological accuracy are called laboratory scales and are in demand in places such as research centers of various profiles, in particular those that often measure bulk. Liquid and solid substances. Scales are also used in jewelry production and for a very long time. Medical laboratories need them no less in the production process of drugs, antibiotics and other things. Without laboratory scales, it would be difficult for food and chemical industries, as well as perfumery. This is how wide, as it turns out, the range of applications for precision laboratory balances.