Name of jewelry scales. What types of scales are there? Some important parameters of the scales

Any jewelry workshop, any pawnshop needs to have electronic scales. Main purpose jewelry scales in the pawnshop is the weighing of precious metals and stones in laboratories, workshops and stores. In addition, jewelry scales in a pawn shop can be used to determine the weight of items with a high degree of accuracy. Jewelry scales are subject to increased requirements for measurement accuracy. Jewelers and pawn shop employees constantly use scales when working with precious metals and gemstones. Jewelry scales must be able to weigh objects in the measures accepted by jewelers: carats, grams, ounces. Weighing of precious metals, jewelry and other household items made of precious metals and precious stones, scrap and waste from them is produced on scales that provide the necessary weighing accuracy:

gold, platinum, palladium in the form of ingots, semi-finished products and products: with a weight of up to 1 kg - 0.01 g; with a weight over 1 kg - 0.1 g;

gold, platinum and palladium in the form of scrap - 0.1 g;

silver in the form of products - 0.1 g;

silver in the form of ingots, semi-finished products and scrap - 1.0 g

The permissible error limit of the scales used should not exceed the values ​​​​defined by GOST.

What to consider when choosing scales

When choosing scales you need to know:

How much are you willing to spend on purchasing scales?

The division price - or this term is also called the discreteness of the count and is denoted by the letter - d. Both definitions are equivalent terms. Here you need to keep in mind that not a single model of scales can do without specified parameter, it is he who determines the weighing accuracy. The lower the division value, the higher the accuracy of the scale.

The highest weighing limit is the upper limit of the measurement range, or simply put, it is the mass that the scales are able to measure. NPV - important characteristic any scales. The recording of the LEL values ​​is indicated in the documentation of the scales or on their body. If you try to weigh a load heavier than the LEL, the device will most likely display either an incorrect weight or an error message. Often the NEL value for scales is the most important characteristic.

The lowest weighing limit is the lower limit of the measuring range or the minimum mass that the scale can weigh.

Type of scale calibration - the standards stipulate that scales with divisions of up to 1 gram must be calibrated with a weight. In this case, the calibration process can be external (i.e., calibrated with an external weight or several weights) and internal (i.e., the internal mechanism of the scale allows calibration with a built-in weight; in this case, built-in calibration is divided into self-calibration, where the scales themselves determine the calibration time and do not require outside human assistance; automatic calibration its difference from self-calibration is that outside help a person is required for the task of the interval of calibration processes).

Convenience: A number of models have modern graphic display with tips to help you use everything software capabilities without special training. Moreover, in some new models the height of the digits reaches 16.5 mm. Almost all models of this level have full package standard weighing programs: taring, selection of weighing units, quantity counting, summation of samples

The cost of scales also depends on the manufacturer. There are many manufacturers of laboratory scales. The most famous in Russia trade marks: Shimadzu, CAS, Shinko, OHAUS, Kern, AND, Sartorius and Mettler Toledo. From Russian manufacturers - Vesservice and Gosmetr.

Verification of measuring instruments is a set of operations performed by the bodies of the state metrological service (other authorized bodies, organizations) in order to determine and confirm the compliance of the measuring instrument with the established technical requirements. Positive results of verification of measuring instruments are certified by a verification mark or verification certificate. Measuring instruments subject to state metrological control and supervision are subject to verification by the State Metrological Service upon release from production or repair, upon import for import and operation. Only certified measuring instruments are allowed to be sold and rented. There are four types of verifications:

primary- produced when scales are released from production or repair or when imported;

periodic- scales in operation are subject to it, the frequency of such verification is once a year;

extraordinary- carried out when operating the scales in following cases: in case of damage to the verification mark (state verifier seal) or loss of the verification certificate, when putting the scales into operation after long-term storage, after re-tuning, if there is a known or suspected impact on the scale or if it is not performing satisfactorily,

inspection- carried out during state metrological supervision in the presence of a representative of the inspected legal entity

Weighing of industrial products, intermediate products, scrap and waste containing precious metals in quantities of less than 5 percent is carried out on scales with a permissible weighing error of +0.05 percent of the weighed mass.

The weight of diamonds and processed gemstones is determined in carats on scales that provide the necessary weighing accuracy. The weighing error, depending on the mass being weighed, should be:

with a weight of up to 1000 carats no more than + 0.01 carats;

with a weight from 1000 to 5000 carats no more than + 0.04 carats;

with a weight over 5000 carats no more than + 0.08 carats.

Weighing of precious stones in raw materials (except for diamonds) is carried out on scales that ensure the weighing accuracy established technical specifications. (when included, as a rule, carats are the basic unit of weighing)

Some important parameters of the scales

Common models of scales used in pawn shops

In order to choose the right manual scales, you need to understand what options are available on the market, what pros and cons this or that model has, and what the principle of their operation is. There are two types of kitchen hand scales: mechanical and electronic. Let's look at each model in detail.

Scales with hook – indispensable assistant in the household. It's practical and handy tool for weighing products. It doesn't take up much space and is easy to use. With its help, you can weigh both piece products: potatoes, carrots or cabbage, and bulk products: sugar, cereals, flour.

The principle of their operation is quite simple. Inside the case there is a rigid spring with an arrow and a metal hook attached to it. A load is hung on this very hook, under the weight of which the spring begins to decompress, and the arrow rises up the graduation scale.

There are two types of mechanical scales:

Linear steelyard. This device for weighing products is a small rectangle with a measurement scale. As a standard, this device can weigh products weighing up to 10 kilograms. The length of one division is 100 grams. This device is preferred by those who do not need high measurement accuracy. Due to the portability of the device, it is convenient to take it with you.

This model is similar to a small portable mirror with a division scale instead of a reflective surface. Mechanical scales of this type can be designed for both small and large weights.

Those in whose kitchen this measuring device has been “living” for a long time have no questions. But those who are thinking about buying a mechanical steelyard should weigh the pros and cons.

pros mechanical hand scales:

1. Small size.
2. Ease of use.
3. Simplicity of the mechanism.

Disadvantages These models can be considered:

1. Weighing inaccuracy.
2. Difficulty working with products weighing less than 500 grams.

Electronic

Manual electronic scales with a hook are new generation devices. Externally, the units resemble old mechanical models, but in terms of functionality they are not inferior to stationary kitchen scales. This tool requires a battery, usually a AA battery, to operate. The method of measurement also differs. Unlike the division scale as mechanical models, used in electronic steelyard clock face.

When working with this device, it is extremely important to hold it correctly. You should not grab it by the body if the design provides a holding device. This will affect the accuracy of the measurement.

Undoubtedly, this is a more modern and convenient model. TO merits electronic steelyard include:

1. Compactness.
2. Simplicity.
3. High measurement accuracy.
4. Availability of backlight function.
5. Ability to select a unit of measurement.
6. There is a memory function that allows you to weigh without taking into account the tare weight.

As for the disadvantages of this device, there are essentially none. Of course, the price of an electronic device is slightly higher than a mechanical one, but taking into account all the functionality, it is very affordable.

Conclusion

When choosing a manual steelyard, you should clearly understand for what purposes it will be used. If measurement accuracy is not important to you and you do not need the memory function, feel free to choose the mechanical option. Well, for lovers of comfort in the market of measuring instruments, an electronic steelyard - best solution question about choosing scales.

Scales(usually this term is used in the UK and Australia, "measuring device" in South Asia or "scale" in the USA) are a measuring device for determining masses object. They are used in many industrial and commercial settings. Variety of products, ranging from feather products to tractor trailers, are sold by weight. Specialized medical and electronic scales are used to measure human body weight.

Name "scales" comes from a dish on which objects requiring weighing and weights were placed. Oxford Dictionary in English gives this definition: “Weighing device. A bowl or two bowls and a balancer". Spring scales or spring steelyard measure force by balancing force gravity due to spring force. Counterweight or electronic scales compare masses by balancing the force of gravity and the mass of an object relative to gravity. Any scale, whether counterweight or electronic, can be calibrated to use units of force such as Newtons or units of mass such as kilograms. But a scale with a counterweight or with a traditional pendulum for comparing masses will show the mass correctly even if it is moved to a different (non-zero) gravitational field (but they will not give correct data if they are calibrated in force units). At the same time, the spring scale will correctly indicate the force in different gravitational fields (but won't if they are calibrated in mass units).

Electronic

Microbalances

A microbalance is an instrument capable of making precise measurements of objects of relatively small mass: on the order of a millionth of a gram.

Analytical

Analytical balances are a class of instruments designed to measure small masses on the order of sub-milligrams. The measuring cup of an analytical balance (0.1 mg or less) is located inside transparent case with a door made so that dust does not get inside. Therefore, any air currents in the room do not affect the operation of the scales. This type of housing is often called a protective housing. The use of a ventilated safety housing, which has a uniquely designed aerodynamic surface, allows the creation of a smooth air flow without turbulence, which prevents their vibrations. This makes it possible to measure mass with an accuracy of 1 µg without fluctuations or loss of product. In addition, the sample being weighed must be at room temperature to prevent natural convection from forming air currents within the enclosure and the associated weighing error. Single pan mechanical scales maintain consistent response throughout useful power, which is achieved by maintaining a constant load on the beam, and thus the fulcrum, by subtracting the mass on the same side of the beam to which the specimen is added.

Electronic analytical balances measure the force required to resist the mass being measured, not the actual mass. Therefore, they must have calibration adjustments to compensate for gravitational differences. They use an electromagnet to create a counter force against the sample being measured and output the result by measuring the force required to achieve equilibrium. This measuring device is called an electromagnetic force recovery sensor.

Strain gauge

IN electronic version spring balance, the deflection of a beam supporting an unknown mass is measured using a strain gauge, which measures electrical resistance and is length sensitive. The capabilities of such devices are limited only by the beam's resistance to deflection. The results of several auxiliary points can be added electronically, so this method is suitable for determining the weight of very heavy objects such as trucks and railway cars, and is used in modern scales.

Store

This type is used in bakery and grocery stores, when selling delicacies, seafood, meat, vegetables and fruits, as well as other perishable goods. The store type can print labels and receipts, weight, brand/quantity, unit price, total cost and in some cases container usage. Some modern scales Supermarkets print an RFID tag that can be used to track items if they are tampered with or returned. In most cases, these types of scales are hermetically calibrated so that the display readings are correct and cannot be tampered with. In the USA, such devices are certified by the National Conference of Weights and Measurements, in South Africa - by the South African Bureau of Standards, and in the UK - by the International Organization of Legal Metrology.

Mechanical

Manual spring

Manual spring scales measure mass using the distance a spring deflects under load. This contrasts with the balance type, which compares the torque on a lever at a sample weight with the torque at a standard weight using a horizontal lever. Spring scales measure force, which is the tensile-compressive force acting on an object relative to the local force of gravity. They are usually calibrated in such a way that the measured force is translated into mass at Earth's gravity. The object to be weighed simply hangs from a spring or is placed on a platform with a rod.

In spring scales, the spring either stretches (as when weighing in the produce department grocery store) or compresses (as in simple bathroom scales). According to Hooke's law, each spring has a proportionality coefficient that shows how difficult it is to stretch it and by what distance. A spring of known stiffness is used (see Hooke's law), and the displacement of the spring is measured in any number of different ways to obtain an estimate of the gravitational force associated with the object. Rack and pinion mechanisms are often used to convert the linear motion of a spring into a circular scale.

Spring type has two sources of errors, which are not in the balance: the measured weight varies depending on the local gravitational force (by as much as 0.5% in different places on Earth), and the elasticity of the measuring spring may vary slightly with temperature. When properly manufactured and set up, however, spring scales can be considered legal for trade. To eliminate temperature errors, commercially available spring scales must either have a temperature compensated spring or be used at a fairly constant temperature. To eliminate the effects of variations in gravity, spring scales marketed must be calibrated where they are used.

With pendulum balance

Pendulum scales do not use a spring. This design uses pendulums that act as a balance and are not affected by differences in gravity. Scales of this design are manufactured, for example, by the Scale Company in Toledo.

Hydraulic or pneumatic

Where needed huge pressure For example, to measure cranes, hydraulic force is used to determine the mass. The test force is applied to the piston or diaphragm and transmitted through hydraulic lines to a Bourdon tube dial indicator or electronic sensor.

Lever

Lever scales (also balance, rocker or laboratory) were the first mass measuring instrument. In their traditional form, they consist of a horizontal lever with equal arms called beams, and a scale suspended from each arm. (This construction is related to the fact that the word “scales” is used in the plural). The unknown mass is placed on one pan and a standard measure of mass is placed on the other pan until the beam approaches its maximum possible equilibrium. In precision balances, a massive slider moves along a graduated scale. The position of the slider gives a subtle correction to the mass value. Although technically it is weight rather than mass that is being compared, the weight of an object is proportional to its mass, and weights used in such cases are usually designated in units of mass.

Lever type is used for precise measurement mass, since, unlike spring ones, their accuracy does not depend on differences in gravity, which can vary by almost 0,5% in various places on Earth. A change in the force of the gravitational field caused by the movement of the lever will not change the measured mass, since the moments of forces on both sides of the beam are affected equally. In fact, a lever scale will measure mass correctly even on other planets or on the moon, or anywhere there is constant gravity or acceleration.

High measurement accuracy is achieved due to the fact that the balance fulcrum is essentially frictionless ( the tip of the knife is in the usual way checks). The pointer is attached to a beam, which amplifies any deviation from the equilibrium position. Next, the lever principle is used, which allows the application of a fractional mass to the movement of a small mass along the measuring arm of the beam, as described above. For greater accuracy, buoyancy in air must be calculated, the effect of which depends on the density of the masses involved.

The original form of a lever scale consisted of a beam with a fulcrum in the center. To achieve maximum precision, the fulcrum will consist of a sharp V-shaped rod mounted in a shallow V-shaped bearing. To determine the mass of an object, a combination of initial masses is hung at one end of the beam, while an object of unknown mass is placed at the other end. Because of their high precision operation, center beam balances are still one of the most accurate instruments available and are commonly used for calibrating weights.

Some mechanical lever scales also use a dial (with counterbalancing weights instead of springs), a hybrid design with the advantages of balancing accuracy and easy-to-read results.

Humanity has been using devices to determine weight for many centuries - the first mentions of them were discovered 2.5 millennia before new era. Today they are used in many fields of activity; without the participation of these very precise products it is impossible to imagine, for example, trade. There is a wide range of types of scales, so to find out their features, you need to familiarize yourself with their variety.

Many consumers use these devices in everyday life, but do not think about how they work and how they differ from each other. To fill these gaps, just read our article carefully.

According to GOST 29329–92, all types of scales are classified in this way.

1. Application area.
2. Weighing accuracy: there are two accuracy classes - medium and normal.
3. Location - built-in devices, floor-standing, table-top, hanging, stationary or mobile.
4. Type of balancing device - mechanical, electronic or combined.
5. Load receiving device - hopper, platform monorail, conveyor, bucket or using hooks.
6. The method of achieving balance is automatic, semi-automatic and manual.

All types of mechanical scales are gradually being replaced with more advanced ones, since they do not require large material investments to maintain performance. Electronic analogues have many advantages, for example, in warehouses they are connected to a computer in order to enter materials for their intended purpose into sections of the accounting system when receiving products.

Application area

Weighing devices are used everywhere - today it is difficult to find an area of ​​human activity that does not use different kinds scales

Industrial

Used in manufacturing plants to measure incoming cargo and output products. They have a floor arrangement, because the size is quite significant, as is their own weight. Their modification is as follows:

• mobile;
• impact resistant;
• dust and moisture resistant.

The same products are installed by logistics companies on their warehouse terminals.

Crane

There are situations when it is necessary to weigh cargo when moving it using powerful cranes in a suspended state. The use of such devices is justified in sea and large river ports, at bases for storing construction materials, and at railway freight stations. Crane scales are distinguished by weighing accuracy, as well as lifting capacity in the range of 1-10 tons, installation method.

Automotive

Used for weighing empty or loaded vehicles when they are fully loaded onto the device. Used in the metallurgical, food, chemical industries, various databases, warehouse storage terminals, elevators, as well as in construction and agriculture.

Pallet

Designed for weighing various cargoes on pallets - they are used wherever there is this type of cargo arrangement. The equipment is quite compact, but capable of weighing large loads. For operator convenience, there is a display; the platform where pallets with cargo are installed is equipped with sensors that record weight.

For trade

Commercial scales are designed in the same way: a two-sided display so that the seller and buyer can observe the entire process. There are several electronic types such products:

1. Trading devices on counters calculate the cost of goods after entering the price per 1 kg.
2. Self-service stores are equipped with scales that weigh the goods and immediately punch out a receipt, where the weight and price must be indicated.
3. Packaging scales are installed in the packaging department of large supermarkets, bases where food kits for small retail chains are stocked.
4. Warehouse scales are a rather bulky device on which you can weigh loads from 60 kg to 2 tons.
5. Products with printed labels are used for self-service stores.
   In large stores, check scales are installed in front of the cash registers, where each customer can check the weight of the purchased package.

Postal

Many readers have at least once used the services of post offices to send some items or long-term storage products - there are also scales installed there that are directly connected to the computer. They can weigh a parcel up to 10 kg or valuable letter weighing several grams, since the accuracy class allows them to determine weight up to 1 g.

Today in all post offices you can observe the use of only electronic products - they work in offline mode, and the employee only needs to issue a printed receipt and collect the payment. Such products have a number of advantages over mechanical analogues:

1. Digital display showing weight.
2. Function optimal choice discreteness and limits.
3. Protective properties.
4. Self-diagnosis.
5. Communication with a computer.

For parcels, parcels and registered letters one type of scale, and for containers - accordingly another, but all have a fairly small error.

Appliances

Scales are also necessary in everyday life - they differ quite greatly in design, operating principle and quality of materials. In the kitchen, bowls are used for weighing bulk products and liquids, platforms provide weighing of goods for various purposes and parameters. The industry produces mechanical and electronic devices for weighing food, as well as to determine the user's own weight.

Medical

Here desktop and floor options. Since in some cases special precision is needed, electronic versions of products are used, which are divided into two types:

• equipped with display and mechanical device weighing;
• devices having high accuracy measurements.

Scales are widely used for weighing babies - they are used in maternity hospitals, children's departments of hospitals and clinics, they are compact, as well as a convenient bowl where babies are placed. Special scales, made together with height measurements, are used in hospitals and clinics - they simultaneously measure height and accurately determine the patient’s weight.

Laboratory

In research centers, only electronic versions are used that are connected to a computer - the accuracy of such scales is not relative and sometimes reaches hundreds of grams. In some cases it is necessary to carry out hydrostatic weighings to determine the exact density of solids or liquids.

Jewelry

To especially precise scales These include products that are used in jewelry, where absolute confidence in the accuracy of the indicators is needed. Experienced jewelers, when determining carats, use products where the test pressure is no more than 0.01 grams. An error of 1 g is allowed only when accepting scrap precious metals. Jewelry factories use only highly precise equipment.

How do scales work?

For convenience, we will consider floor products, because they are available in almost every home, the differences are minor, for example, with kitchen ones for weighing products in the range of 5-15 kg.

Mechanical

Everything here is the same as many years ago: a primitive design - a compressed spring, rigidly fixed inside the product, straightens under the weight of the object and moves the arrow associated with it along the scale to the desired number. The division price of mechanical scales is 1 kg, very rarely - 0.5 kg, so the error of such mechanisms varies from 0.5 to 1 kg.

• lack of strict accuracy;
• outdated technological nuances.

You should buy such products only when you occasionally need to check your own weight, and for those who scrupulously monitor their body weight, more accurate analogues from the latest electronic devices are suitable.

Electronic

At first, these devices had a similar principle of operation as the mechanical version, only the weighing result was shown by a digital display, so cheap models today are practically no different from their mechanical counterparts. The operation of real electronic ones is radically different: some measure weight using special plates, while others use voltage sensors.

These devices consist of the following main parts:

1. A body that is made of plastic or glass, because the use of any metal makes the product heavier and greatly increases its cost.
2. Display or digital screen, it is designed to display the result; today models are already being produced that store the results and compare them. U expensive models The percentage of body fat, muscle and bone skeleton is displayed on the screen.
3. Load cells are small plates located above each leg of the scale, and when we stand on the platform, they are deformed, but the change in their structure cannot be determined with the naked eye. Excess weight is distributed evenly between them, the data from each device is summed up, and the total value is calculated on their basis.
4. A printed circuit board with a microcircuit controls the action of the plates and displays the result on the display.

Products based on voltage sensors are considered more progressive. The simplest sensor is a thin copper wire through which a low current is passed; under the influence of gravity, it changes the resistance and the magnitude of the electrical signal passing through it. These devices have no mechanical parts, the error is no more than 100 g, but there are high-precision products, but their cost is very high.

The disadvantages of electronic scales include the following factors:

• we must treat them with care, because they are afraid of mechanical impact - blows, falling heavy objects;
• They are powered by batteries, which must be constantly changed.

Price electronic devices significantly higher than mechanical analogues, which can also be attributed to negative qualities.

Characteristics of scales

According to experts, it is almost impossible to absolutely accurately determine the mass as a result of weighing, because there are always factors that interfere with this:

1. Correct and precise installation scales
2. Ambient temperature.
3. Operator's physical well-being and much more.

The error for each type of scale is individual and can vary from 1 to 100 g; it must be indicated in the product passport.

The largest and smallest weighing limits are the measurement limits. They directly depend on the mass of the object that needs to be weighed: for example, a bird carcass can be weighed on a scale with a limit of 15 kg, but it will no longer be possible to determine the weight of a quarter of a pig carcass, just as it is impossible to accurately weigh a bag of spices on a scale with a division value of 100 g. 10 g. The weighing range is the area between the smallest and largest weighing limits. The metrological characteristics of products are called accuracy class. The price of an instrument scale division is the difference between adjacent divisions; it can be different depending on the weight limit.

Sensitivity is the ratio of the output signal measuring instrument to the value causing its change, it can be relative or absolute. It is measured during the manufacture of the product in the factory. One of the main characteristics is considered to be an indicator of reliability or probability of failure-free operation; life time; resistance to external influences, and for electromechanical and electronic options - electrical power parameters.

Accuracy class

Today, according to OIML, there are only three classes: special, high and medium. They are assigned on the basis of tests upon acceptance of the product by the quality control department at the factory, while the errors of the device are normalized or how inaccurate the scales can show the result. Any scales located in the state point of sale, are verified at least once a year.

When asked by customers whether scales in supermarkets and stores lie, a specific answer can be given: this can only happen if the calibration is violated. This place is sealed, and opening it will result in a significant monetary punishment for all those involved in the case, the seller and the manager. Therefore, owners or sellers use other methods: they install a transparent sheet of plastic on the platform for placing goods - it weighs no more than 100 g, but considering throughput self-service supermarket, the result is quite noticeable, but not in favor of the buyer.

conclusions

The range of scales is quite representative, so before you go shopping for something new, find out among all the residents of the apartment which parameters are their priority. Experts advise electronic scales without additional functions: they will not damage your family budget and are suitable for all ages, even very large families.