All electrical wiring must be safe for human life. This is one of the most basic requirements for electrical installation. It is especially necessary to remember the places where the wires are connected, because it is there that overheating, contact failure or even fire can occur. That is why in these places it is necessary to make reliable insulation. One way to isolate is to use heat shrink tube(HERE). This type of protection has many advantages over other types of protective insulation for cable connections. But in order to properly use heat shrink, you need to know what it is, what such a tube is for, and how to choose the size. That is what this article will be about.

Main purpose

The main purpose of heat shrink is to isolate current-carrying conductors. Due to its electrical insulating properties and easy installation can successfully replace conventional insulating tapes.

At this time, heat shrink tubing, which is used for protection, can be easily purchased at electrical stores. Popularity this product as insulating material is the ability to reduce its diameter due to high temperature. The required shrinkage temperature reaches 120°C. However, in order to do this, you need to know how to heat the heat-shrinkable tube. Due to the heat, the heat shrink wraps around the insulated object very tightly and securely, providing good insulation, as well as providing mechanical protection for wires.

Manufacturers produce tubes different sizes and they are also color-coded. Due to this, they are used not only for good insulation, but also for further determining the purpose of the insulated wire.

For example, for marking wires direct current use red for plus and black for minus. And for marking five-core electrical cables brown, white, black are used, which indicate phase conductors, zero is indicated in blue, grounding is yellow-green.

The use of HERE for cable marking is quite convenient, because the heat shrink tube does not need to be pulled over the entire length of the wire. You just need to stretch a small piece of heat shrink over the insulation to the end of the wire, as shown in the photo above. This marking is very reliable, and is not afraid of external influences, as well as temperature changes. Its service life is more than twenty years. This product is durable, inexpensive and very easy to use.

Advantages and disadvantages

Compared to other types of insulation, heat shrink has at least four advantages.

Firstly, since the heat shrink tube fits very tightly, it does not move due to various mechanical influences. Secondly, installation is a simple and fast process, but you still need to know some rules of use. Thirdly, after shrinkage, the insulation material becomes more durable, so the wire becomes even more resistant to mechanical damage and acquires additional rigidity at the junction. And the service life is much longer than that of conventional electrical tape. The fourth plus is a wide scope.

Among the shortcomings of the HERE tube, the following can be noted:

1. It is impossible to reuse, because when heated, it changes its diameter, so it will definitely be damaged when removed.
2. The price of a heat-shrinkable tube is higher than the price of electrical tape, but not so much that it becomes a decisive factor when choosing a protective and insulating material.

If any other shortcomings are found during use, then these are the shortcomings of the selected manufacturer.

The video below provides a visual comparison of heat shrink and electrical tape:

Where is the tube used HERE

While heat shrink tubing's primary purpose is to insulate contacts, there are other ways to use it:

• Insulation of plumbing and metal pipes from aggressive environment.
• Shrinkage on a metal butt or wooden support Power lines in order to protect against corrosion and decay of wood in the ground.
• Longitudinal sealing of cable bundles. Despite the external insulation, you can use a special tape that completely fills and also insulates the space between the conductors of the wire.
• To improve the ergonomics of the handles sports equipment and building tools through the use of corrugated and ribbed tube surfaces.
• transformation simple tools, for example, screwdrivers in dielectric using insulating HERE.
• Wire protection against high temperature. There are products, the operating temperature range of which varies from -65°С to +260°С. This protection helps the wire to withstand such working conditions, even if there is a source of heat and fire nearby. Such types of heat-shrinkable tubing are called fluoroplastic or teflon.

Specifications of heat shrink tubing

First you need to know what the heat shrink for wires is made of. It is made of polymer, thanks to which it can change and shrink. The size of the tube HERE can be reduced by half or even six times. The shrinkage ratio of the product ranges from 2:1 to 6:1.

Also, heat shrinks come with adhesive layer, they are used when connections need to be very securely sealed to protect against moisture and corrosion. The adhesive layer achieves additional strength of the joints.

Heat-shrinkable tubes differ in the composition of the polymer. Some are made from PVC, elastomers, polyolefins, and various other materials. It is important that the product is resistant to fire, actions ultraviolet rays and also to have good mechanical properties.

It is also important to talk about the dimensions of heat-shrinkable tubes. All manufacturers put a designation on the product that will indicate its dimensions. The diameter is given both before and after shrinkage. The first digits indicate the internal size before shrinkage, and the next ones indicate either the diameter or the coefficient by which it can be calculated. The basic or standard ratio is 2:1. The maximum tube diameter of HERE is 120 mm, and minimum size– 2 mm before shrinkage.

The most required heat shrink sizes are provided in the table:

If you want to know how to choose heat shrink tubing, please watch the video below:

How to use heat shrink for wires

It remains to learn how to use heat-shrinkable tubing. So, first you have to choose suitable size heat shrink. If necessary, it is necessary to cut off a suitable piece that would overlap the insulated area, taking into account the fact that there will be longitudinal shrinkage when heated. Usually it is up to 10%, this information is indicated by the manufacturer. On the surface, as well as on the sections of the cut tube, there should be no damage or any burrs, because they can contribute to the rapid destruction of the material.

First, a tube is pulled over the cable HERE, and then it is necessary to make a connection, over which heat shrink will be put on. After joining, it must be heated with movements from one side to the other, in order not to get a large longitudinal shrinkage. This can also be done by heating from the middle of the joint to the edges. The second method is applicable to sufficiently long sections.

It should be remembered that it is impossible to warm up at the same time from both ends because an air bubble may remain, and this is very undesirable. Wrinkles may also appear on the surface. The heat-shrinkable tube should be heated very carefully and evenly so as not to overheat in some place, because a bubble or a break in the surface may appear.

The heating rate and temperature are determined by experience. However, one should not rush, especially if there is no experience in this direction. If heating is performed too quickly, or at too high a temperature, the heat shrink may be damaged.

The insulation process itself is not too complicated; if desired, you can independently insulate the wire. However, to begin with, you can experiment on some piece of wire and make sure that everything is done correctly, and only then take on the isolation of critical connections.

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It is not difficult to buy a heat shrink tube in Vladivostok, but its quality leaves much to be desired. Translucency bothers me the most. The train of thought is simple: if the heat shrink is translucent, like a cover for a school notebook, then its insulation is poor. And to be honest, all these semi-pink and not green tubes do not harmonize with my wires of exclusively red, black, yellow or white color.

I prefer to buy heat shrink tubing from the hobbyking online store - there the price is more attractive, and the quality of the tubing is an order of magnitude higher. Just do not consider me an avid buyer of heat shrink: I bought once and took a meter of each tube from the diameters and colors I needed - so far there is enough, although the stocks of some are already running out. If you need more, I'll buy it there. As practice shows, a one-meter set is enough for a year of leisurely use. Heat shrink tubes are marked according to their original, primary diameter, that is, according to the size before shrinkage. On average, all heat shrinks shrink twice evenly. Some more, some a little less. In any case, it is worth choosing a tube so that the diameter of the wire is slightly larger than half the diameter of the heat shrink. For example, 14mm heat shrink tubing will shrink to 7mm, in which case it must be used with a wire at least 8mm in diameter.

How to heat and shrink heat shrink tubing?

The best tool for this job is a blow dryer. However, this thing is not cheap and buying it just for the sake of heat shrink is stupid. If you have a temperature controlled soldering iron or Soldering Station, then you can burn the tube with the thick part of the soldering iron. Not a sting, but the place where he hides a heating element. Quite a working option.

Can an open flame be used for heat shrinking?

By an open flame, I mean any source of fire: a match, a lighter, a candle. In principle, the tube can be seated with an open flame, but a few points must be remembered:

1. The tube with a sharp shrinkage can be deformed and slip
2. With due diligence, heat shrink tubing can be burned through
3. The colored tube may become sooty

The main problem with using an open flame is that the source is always at the bottom, so the structure must be constantly rotated over the flame so that the tube is compressed evenly. By the way, it is advisable to keep it three to four centimeters from a visible flame: the temperature is most optimal there. It is not necessary to stick the tube directly into the flame or its base: the temperature is lower there. I do not recommend using turbo lighters and gas burners - the pipe will deteriorate in an instant!

Why is heat shrink better than classic blue electrical tape?

First, the tube does not unwind over time. Secondly, it does not stick to the insulated material and does not leave an adhesive layer on it. And when correct selection color and diameter looks more aesthetically pleasing. By the way, it is much easier to remove the tube: it is enough to make a longitudinal incision. Heat shrink is also indispensable for insulating closely spaced contacts, for example, on connectors: it does not need to be wrapped, and therefore free space is not required.

Why is heat shrink tubing worse than regular blue electrical tape?

Is it that it cannot be used to isolate structures complex shapes, whose size changes. If the connector has a diameter of 10 mm, and the wire is only 3 mm, then the tube simply will not reach the wire or fit on the plug.

What sizes are there?

The hobbyking site has tubes from 2 to 100 millimeters. I once was in a store with electrical goods and all sorts of powerful things - there were heat shrink tubing with a diameter of 25, and if I'm not mistaken, even 50 centimeters. Tubes up to one or two centimeters in diameter really look like tubes. And the larger ones are flattened into stripes and look like a ribbon. It is important to remember that they are all marked precisely by the diameter, and not by the width of the flattened tape. For example, a red tube with a diameter of 14 mm looks like a tape with a width of 24 mm.

The diameter of the tube and its width in a flattened state are two different things!

Which ones to take?

I'll tell you on personal experience. So here's what I bought:

• 25 mm, transparent - convenient for isolating ESC and any USB boards (hubs, modems, wi-fi whistles)
• 16 mm, transparent - suitable for connectors and some small boards, sensors or sensors
• 14 mm, red - I practically didn’t use it, because I took it for my ESCs, but didn’t calculate the dimensions; most often I cut it into thin rings and mark some cables; it is also indispensable for my Turnigy 4WD Rally car
• 6 mm, blue - for power wires; because of the color that is not the most popular for me, it was practically not used, but it will be useful for many electricians
• 6 mm, yellow - for power wires; used more often since I use the 12 volt line extensively
• 6 mm, black - actively used for wires and connectors (3.5 and 4 mm bullet)
• 5 mm, black - the absolute leader in use in its diameter, ended
• 5mm yellow - used to insulate motor connectors (3.5mm bullet)
• 5 mm, blue - helps in the color differentiation of wires, although it is not so actively used
• 5 mm, red - the second place in terms of use in its diameter, I already have very little of it left
• 4 mm, black - completely over, you need to re-order
• 4 mm, red - a little bit left and still comes in handy
• 4 mm, yellow - there is quite a lot left, usually 12 volts are not carried out with such thin wires
• 3 mm, black - over, because it is very useful for almost all wires
• 2 mm, red - ended quickly
• 2 mm, black - ended even faster

Obviously, the most popular with me are small diameters, but this is understandable: small models are thin wires. Diameters of 5-10 mm will be of interest to electricians and car enthusiasts: the former work with serious wires, while the latter like to seal everything. Larger diameters have even more specific applications, except for one: heat shrink can be stretched over tool handles and make it more convenient (and electrically safe) to handle. I use large gauges to insulate modules and boards.

27.09.2018

Heat shrink tube (thermoshrink, HERE) tends to reduce its transverse size when heated. In the longitudinal direction, this material also decreases when heated, but slightly - by a maximum of 15%. Heat-shrinkable tubing is used in the energy and electrical fields, in instrumentation, the automotive industry, the aviation industry and other fields of activity. For its production are used different materials: polyolefin, elastomers, fluorine-containing elastomers, polyvinyl chloride, polyester, EPDM. To figure out how to use heat shrink tubing in a particular case, you need to know its characteristics. This:

1. the degree of shrinkage - it depends on the wall thickness of the HERE and the properties of the material;
2. diameter cross section For example, to protect batteries, sewer pipes and other large items use heat pipes large diameter, and for wire contacts - narrow HERE;
3. the presence of an adhesive layer - when the thermotube shrinks with a layer of epoxy glue, it melts, closes the irregularities and ensures 100% tightness of the joints;
4. polymer composition - the physico-chemical parameters of TUT depend on it;
5. type of coloring - there are monochrome of various colors and 2-color;
6. electrical strength;
7. resistance to temperature influences, the influence of UV rays, chemical substances, fuels and lubricants;
8. physical strength, rigidity, flexibility, softness.

How to properly shrink heat shrink tubing?

To solder heat shrink, you do not need to have special skills. Such tubes easily and tightly fit on various items. To do this, the heat shrink must be heated in a safe way to the desired temperature. Before using heat shrink, you must correctly determine it optimal diameter. Its value after shrinkage should be less than the smallest diameter of the product to be insulated. From the coil of the selected heat shrink tube, you need to separate the cut of the calculated length. Its end must be made smooth in order to avoid the prerequisites for the occurrence of a rupture and leakage. The end of HERE should be placed on a section of wire or other object to be insulated. Shrinkage can be performed from one edge to the other or from the central part to the ends. It is recommended to heat the thermotube with a building hot air gun. An alternative to it can be a portable gas burner, soldering iron or other similar tool. IN last resort if you need to shrink a small diameter tube, you can use a lighter or matches. Desired temperature heating is listed in technical documentation to HERE. You should not exceed it: instead of speeding up the shrinkage process, you will get bubbles, charring or tube ruptures due to overheating. In case of local overheating, melting or swelling, you need to remove the heat shrink tube and use a new piece.

Rules for installing heat shrink

To crimp the heat shrink tube as best as possible, you need to follow simple rules:

Application of large diameter heat shrink

Large diameter heat shrink tubing is used for anti-corrosion protection of metal pipe joints, creating an insulating layer on lithium batteries, sealing joints of cable glands and solving other problems. The areas of application of heat shrinks are extensive. They perform the functions of a covering and protective material for various equipment, perform the tasks of an insulator, and provide mechanical and anti-corrosion protection. With their help, it is possible to enhance the strength and frost resistance of installations, to give marketable condition a variety of products, fix complex blocks of separate parts. They are in demand HERE when creating interior decorations, and in other unexpected areas. The principle of using a wide heat shrink is almost identical to how to use a heat pipe for wires of a smaller diameter. But if you can try to shrink thin tubes with a lighter or matches, then to work with a large diameter HERE you need a professional hair dryer or burner.

There are several ways to heat up when working with HERE heat shrink tubing. Each of them can be used with different types heat shrink, but some may not fit or even spoil the insulation.

The cheapest and most controversial option is matches. They are used when there is no other tool at hand, and heat shrinkage of very small sizes and sections. For large sizes it's not the best option.

The result is not a very neat form of compression of the tube, and the whole process can take a long time if we are talking about larger items. And how many matches will be required if you need to isolate not one connection, but several dozen?

A lighter in this matter is also not always an assistant.

In those rooms where it is impossible to use a flame or an open fire, they try to adapt an ordinary hair dryer for drying hair. However, he is not able to create the required temperature for high-quality shrinkage compression.

The optimum shrinkage temperature is from 90 to 140 degrees, depending on the brand of the product.

At household hair dryer the outlet flow temperature is low, just a few centimeters from the nozzle, it can deliver about 70C. Highly focused nozzles can help with heating small diameters, but the use of non-standard ones leads to the failure of the hair dryer itself. But there are thermotubes with a shrinkage of 350 degrees!

As a result, you may end up with an uncompressed or not completely isolated junction, where water can easily penetrate and absorb moisture. Therefore, instead of using improvised means, try to always use a professional tool.

Pipe tool HERE

In fact, there are 5 types of such a tool for heat shrinking in everyday life:

• • high-temperature building hair dryer (choice + order)
  • portable butane gas burners (you can buy)
  • gas soldering irons (check current prices)
    
  • propane burners
    
  • infrared burners

    The industrial hair dryer is the ideal tool for thin wall tubes. It has in its assortment not only temperature control, but a variety of nozzles. You can choose the required set for yourself by following the link.
    

    Of course, if you are not the owner of a cordless tool, then building hair dryer you can only work if you have 220 volts nearby. Even the presence of a generator does not always guarantee the normal operation of the hair dryer due to its high power.
    

    Characteristics

    

    This is its main drawback and inconvenience. In addition, it is not always possible to warm up thick-walled tubes even with a powerful hair dryer. The quality here will obviously suffer.

    Even before you start working with a hair dryer, you will have to hold the tube a little. Otherwise, a powerful jet of air can move it from its place. Infrared burner in this case has an advantage. It does not create air currents, and its rays warm up very quickly.
    

    Just be sure to keep in mind that dark pipes absorb heat much faster than light or multi-colored ones. Forgetting this, you can easily burn through the insulation.

    Gas burners have several flame functions. Heat pipes should be shrinked with a soft flame. How to understand that the flame is soft and suitable for shrinkage? It should contain yellow tongues. The same applies to gas soldering irons.
    

    A propane torch is the only tool that is optimally suited for thick-walled pipes.

    When working with a burner or a hair dryer, you need to constantly make circular translational movements. Do not stop in one place, otherwise you can easily burn through the insulation.

    In general, the choice of shrink tool depends on the following parameters:

    • wall thickness
    • tube size
    • the material from which they are made

    You can read more about these characteristics in the article “10 types of heat shrink tubing.”
    

    Rules for installing heat shrink tubing

    
    

    There is no need to rush though. First, the product warms up and shrinks around the entire circumference, and only then can you move forward gradually.

    • remember that heat shrinkage decreases not only in diameter, but also along the entire length

    The decrease, of course, does not occur by 2.3 times, but by several percent (maximum 15%). So do not be surprised if the tube HERE was originally 10 cm, and later became shorter by 1.5 cm. Therefore, when choosing the right size segments, always make a small margin.
    

    The reduction in length is especially noticeable when connecting and insulating materials of different diameters.

    For some reason, everyone forgets to take into account the height difference in this case, and it also takes a decent margin.
    

    If you do not know for sure whether the selected size will be sufficient or not, then in this case it is better to ignore the above advice about starting warming up from the middle.

    Here, follow a different rule - heat the tube not from the middle, but from one end to the other. Thus, it is possible to reduce the longitudinal contraction of its length.

    • when the heat shrink isolates any metal surface or a product with good thermal conductivity, it is necessary to preheat this surface.

    In this way, the walls stick together more tightly and the so-called “cold scars” can be avoided. First of all, this applies to tubes of large diameters; without preheating, it is unlikely that it will be possible to avoid skew.
    

    In addition, due to temperature differences, condensation can form, which you "seal" directly onto the insulation. In general, any surface of the material must be cleaned and degreased before work. This is done with a cloth soaked in alcohol or solvent.
    

    If there are extraneous sharp edges on the metal, then they need to be removed and sanded.

    • when cutting and shortening the tube yourself, do it with a sharp knife, and preferably with scissors, so as not to leave burrs. Its edges after the cut should be smooth, only in this case the tube will be seated as tightly as possible.

    
    

    Of course, in this way it is possible to increase its length by more than two times.
    However, at the same time, the thickness of the insulating wall also decreases by the same two times. And accordingly, the electrical strength will already be within smaller limits (for thin-walled ones, this is usually 600V), and someday the phase will definitely break through to the case or another core.

    In addition, the mechanical strength also decreases. How long your connection will now last is a mystery. If, of course, you use this option for low current, telephone cables or USB, then something may work. Plus, no one forbids in the same way to put on top of the first layer, another such stretched thermocambric.

    In the same way, some people manage to increase the width with round-nose pliers, expanding the tube while still cold.
    Thus, trying to make an analogue of expensive 4k1 from cheap HERE 2k1.

Heat shrink tubing, or simply heat shrink, is a special tube that can shrink in size under the influence of high temperature. Absolutely all types of heat shrink are made from polymers that are able to change shape (increase or decrease in size) under the influence of high temperature. Due to this, heat shrinkage has certain properties.

Why heat shrink tubing is needed

The main purpose of heat shrink is to insulate various parts of electrical conductors or junctions. electrical wires between themselves. Also, heat shrinkage also serves to protect against external mechanical influences. Due to its good insulating properties, it is a good alternative to conventional insulating tape, which has been one of the main insulating materials until now.

In addition to the electrical field, heat shrinkage is also used for anti-corrosion and waterproofing. For such purposes, a tube with a special inner adhesive layer is used. The presence of an adhesive layer allows the use of heat shrink on various surfaces such as wood or metal.

Today, heat shrink tubing is produced in a wide variety of colors. For example, it can be white, red, blue, green, black, or yellow. Also available with heat shrink tubing. combined color e.g. yellow-green. Due to a wide range of colors, heat shrink is used not only for insulation, but also for marking conductors of electrical cables or wires.

For example, in three-phase network phases A, B, C are marked in yellow, green and red respectively. The positive and negative wires of DC circuits are marked red and black, respectively, and the protective PE conductor for grounding is marked yellow-green.

Today, you can buy heat shrink in almost any store that sells electrical products. The choice of the buyer is provided with a tube of oval, round and flat shape. The width or diameter of the heat shrink is also different, from the smallest sizes (used to insulate wires of small cross section) to large ones (used for cores of electrical cables of large cross section). You can buy a tube of any length, for example, in the form of a skein (large length) or in the form of a small piece of a certain length.

Pros of heat shrink tubing insulation

Heat shrink tubing has many advantages:

● good resistance to external influences;

● possibility to use in wide temperature ranges;

● resistance to burning;

● relatively low price;

● sufficiently long service life;

● convenience and ease of use (no need for special skills).

Specifications and use

The main characteristics of heat shrinkage are the composition of the material from which the tube is made (PVC, elastomer, polyolefin, etc.), shrinkage coefficient, resistance to various aggressive environments (heat resistance, chemical resistance, oil resistance, resistance to petroleum products), the presence or absence of an internal adhesive layer (adhesive and thin-walled), color (single color or combined).

Heat shrink is very easy to use. The process of insulating wires with heat shrink is even faster than using conventional electrical tape. It does not require special tools and fixtures.

First you need to select a tube of the required diameter, i.e. depending on the diameter (section) of the conductor to be insulated. Then a piece is cut off of such a length that it will completely cover the insulated part of the conductor. It must be cut evenly so that cracks do not appear on the tube.

A piece of prepared heat shrink is put on the part that will be insulated (for example, this is the place where two wires are twisted). Then it is necessary to heat the shrink tube so that it reduces its shape, fits securely on the insulated surface and takes the final shape. For this, a special hot air gun is usually used. Sometimes they use gas burner. If neither one nor the other is at hand, then you can use an ordinary gas lighter. In order for the heat shrink to be evenly pressed against the surface, the effect of temperature starts from the middle of the tube and ends at the edges. You can also start at one end of the heat shrink and finish at the other. It is not recommended to start from both edges at the same time.

The optimum temperature for tube shrinkage is determined either by experience or by asking the manufacturer. By the way, it is worth noting that it is not recommended to heat the heat shrink with an open fire. The shrinkage rate will not increase from this, but it is quite possible to damage the heat shrink itself.

To date, heat shrink tubing is used both in production and in everyday life.

In production, it can be used in assembly electrical cabinets and shields. Those. in each cabinet or switchboard, electrical equipment is connected with wires and electric cables. The wires are insulated with heat shrink, and they are also made color coding. When connecting external cables to cabinets and shields, heat shrink tubing is also used. For example, when cutting power electric cables and before connecting it in a cabinet, heat shrink is put on its cores.

IN living conditions heat shrink is used no less often than in production. Heat shrink insulates not only home wires electrical network. When repairing electrical household appliances heat shrink is also used.