7 tips, which pipes made of cross-linked polyethylene for floor heating, heating and water supply is better to choose

Contents

1. №1.Features of production
2. №2.
3. No. 3 PEX Pipe Stitching Method. Advantages and disadvantages of PEX-pipes
4. №4.Sphere of use
5. №5.Crosslinked polyethylene or metal-plastic?
6. №5.The diameter and length
7. №6.Fittings for pipes of cross-linked polyethylene
8. №7.Manufacturers of pipes made of cross-linked polyethylene

Flexibility, strength, durability, ability to regain shape after damage - these are the main, but not the only, advantages of pipes made of cross-linked polyethylene. They confidently displace other types of pipes from the market, are actively used when installing underfloor heating, plumbing( hot and cold) and heating systems. Are they so versatile? Put all the dots on “i” and try to figure out which pipes made of cross-linked polyethylene for floor heating, heating and water supply are better to choose, what to look for when buying and which manufacturers can be trusted.

№1.Peculiarities of the production of

If you specifically affect ordinary polyethylene( a polymer consisting of carbon atoms and hydrogen), some hydrogen atoms are separated, leading to the formation of a new bond between carbon molecules. The process of obtaining these additional carbon bonds is called

by stitching .They affect polyethylene by various substances and methods, therefore the degree of crosslinking may differ. The optimal rate is 65-85%.

Stitching allows to improve the properties of polyethylene: increased resistance to high temperatures, improved flexibility, wear resistance, the possibility of self-healing after mechanical loads. The stitching process was developed in 1968 by the Swedish chemist T. Engel, but underestimated his invention, finding it uncompetitive. The patent was bought from WIRSBO, which was the first in the world to begin industrial production of pipes of cross-linked polyethylene( PEX) and is still the leader in this field. On the domestic market, such products were not immediately, but now they are very popular.

PEX-pipe is usually consists of three layers of : inside - cross-linked polyethylene, outside - oxygen protective layer, they are connected with glue. 5-layer pipes are also on sale. They have a layer of glue and cross-linked polyethylene on top of the oxygen barrier.

№2.

PEX pipe joining method The most important parameter when choosing pipes from cross-linked polyethylene is the stitching method used by the manufacturer. It depends on the number of additional links formed, and hence the performance of the product.

For the formation of additional bonds( bridges) in polyethylene, such crosslinking methods are used:

• peroxide crosslinking, such pipes are labeled PEX-A;
• silane crosslinking, PEX-B;
• radiation crosslinking, PEX-C;
• nitrogen bonding, PEX-D.

Pipes PEX- A are produced by heating raw materials with the addition of peroxides. The crosslink density of this method is maximum and reaches 70-75%. This makes it possible to speak of such advantages of the , such as excellent flexibility( the maximum among analogues) and the memory effect( when unwinding the bay, the pipe almost immediately takes its original direct form).The bends and creases that may appear during the installation process can be corrected if the pipe is slightly heated with a building hairdryer. The main minus is a high price, since peroxide crosslinking technology is considered the most expensive. In addition, chemical leaching takes place during operation, and is somewhat more intense than in other PEX pipes.

The pipes PEX- B are produced in two stages. First, organic silanides are added to the raw materials, resulting in a pipe that has not been crosslinked. After this, the product is hydrated, and as a result, crosslink density reaches 65%. Such pipes have a low price, they are resistant to oxidation, and have high pressure values ​​at which a pipe breaks. In terms of reliability, they are practically not inferior to PEX-A pipes: although the percentage of crosslinking is lower here, but the bond strength is higher than with peroxide crosslinking. From minuses note the rigidity, so bend them would be problematic. In addition, the memory effect is not here, so the original shape of the pipe will recover poorly. With the appearance of wrinkles will help only couplings.

Pipes PEX- C are obtained by so-called.radiation crosslinking: polyethylene is affected by electrons or gamma rays. The production process requires careful control, because the alignment of the electrode depends on the location of the electrode relative to the pipe. The degree of crosslinking reaches 60% of , such tubes have good molecular memory, they are more flexible than PEX-B, but during operation cracks can form on them. Pins are only corrected by couplings. In Russia, such pipes are not widely used.

PEX- D pipes are manufactured by treating polyethylene with nitrogen compounds. The degree of crosslinking is low, is about 60% , therefore, in terms of performance, such products are significantly inferior to their counterparts. The technology is actually a thing of the past and today it is hardly used.

On sale you can find pipes PEX-EVOH .They differ not in the way of stitching, but in the presence of an external additional anti-diffusion layer made of polyvinyl ethylene, which further protects the product from the ingress of oxygen into the pipe. By the way of stitching, they can be any.

PEX- A pipes are considered to be of the highest quality, but their high cost forces many to use PEX-B pipes. These two types of products are most prevalent in the market, and the choice between them depends on the budget, personal preferences and features of the pipeline, which must be built with their help.

Do not confuse pipes made of cross-linked polyethylene with:

• pipes made of low pressure polyethylene , they can withstand temperatures of not more than + 400C and are only suitable for cold water supply systems;
• pipes from underdeveloped polyethylene Pert , they lack intermolecular bonds, instead of them there is an interlacing of polymer chains and their adhesion. Such pipes have recently appeared on the market; they withstand temperatures up to + 700 ° C;
• pipes made of heat-resistant polyethylene .They are also able to withstand the effects of high temperatures( due to the introduction of heat-resistant additives into the polymer), but will not be able to work at high temperature and other loads for as long as PEX-pipes.

№3.Advantages and disadvantages of PEX-pipes

It is difficult to call pipes made of cross-linked polyethylene a unique and revolutionary product, but has a lot of material advantages:

• maintaining performance over a wide temperature range. The pipe will withstand a short-term lowering of the temperature of the to -500C and increase to + 1200C , the material melts only at a temperature of + 1500C.Remember that optimally operate pipes at a temperature of 0. .. + 950C - if the product is often exposed to critically high or low temperatures, this will affect its durability;
• resistance to pressure drops , the ability to withstand a pressure of 4-10 atm( the specific value of the limit pressure depends on the type of pipe);
• flexibility .In pipes with a different method of cross-linking, the flexibility indicators differ, but, in general, remain at a height;
• high strength, wear resistance;
• durability up to 50 years , provided proper installation and operation;
• corrosion resistance , bacteria, fungus, aggressive chemicals, so the effect of alkalis and acids dissolved in water, the material is easily transferred;
• The smoothness of the walls provides excellent hydraulic performance, which does not deteriorate over time, since the growths on the walls are practically not formed;
• security. PEX-A and PEX-B pipes do not emit any toxic substances, but PEX-C pipes are prohibited to be used in some European countries;
• elasticity .If the water inside the pipe freezes, it will not break;
• molecular memory( in some types of PEX-tubes), which allows the material to restore its original shape;
• material perfectly absorbs noise, which provides comfort during operation;
• low weight( running meter weighs 0.1-0.15 kg);
• relatively easy installation.

Among the minuses:

• sensitivity to prolonged exposure to sunlight, so the pipe is better to hide. If we are talking about installing a system of warm water floors, then this drawback is insignificant;
• with a protective anti-diffuse layer during transportation must be handled with extreme caution. It is not difficult to guess that its damage will allow oxygen into the system and reduce its durability;
• ability to pass oxygen, which leads to corrosion of metal elements of the pipeline. To level this minus, manufacturers make a protective coating;
• diameters of pipes made of cross-linked polyethylene are limited. It is impossible to find large diameter products on sale - their production is very expensive, so products are inferior in competition with metal-plastic or metal pipes. That is why it is impossible to call PEX-pipes universal;
• if water has a high degree of mineralization, then there is still a risk of growth. In this case, it is appropriate to use trunk filters, otherwise the pipes will quickly become clogged;
• fixing the pipe and retaining the shape given to it will require a little more effort than when working with metal-plastic pipes.

Pipes made of cross-linked polyethylene are, of course, more expensive than cast-iron or ordinary polyethylene pipes, but they are still quite accessible, although it will be necessary to spend money on the corresponding fittings. Installation is carried out using a special hand tool. It is very, very important not to damage the protective layer. We can say that the durability of the pipeline will depend on caution when working, which is why it makes sense to entrust the installation to certified craftsmen.

№4.Scope of use of

The performance characteristics of pipes made of cross-linked polyethylene make it possible to use them for construction of the following engineering networks:

• cold and hot water supply;
• heating system;
• water floor heating.

For industrial purposes, PEX-pipes are not used - large-diameter material( for example, for the water main) is expensive.

# 5.Crosslinked polyethylene or metal-plastic?

Cross-linked polyethylene pipes and metal-plastic pipes are the main competitors when it comes to arranging water supply, heating systems or underfloor heating. They have a lot in common. Both types of pipes are quite flexible, durable, resistant to corrosion and relatively easy to install - there is nothing to weld, of course. True, it is still easier to install metal-plastic pipes than PEX-pipes, with which you have to be extremely careful.

Metal-plastic pipes have a slightly higher thermal conductivity coefficient( 0.45 vs. 0.38), but they will not survive the freezing inside the coolant. The PEX pipes, after the water in the system has settled, can be operated as before. Moreover, some types of PEX-pipes easily restore their shape. Resistance to high temperatures and pressure is high in both types of pipes: metal-plastic can withstand pressures up to 25 atm at 250 ° C, can be operated at coolant temperatures up to + 950С with short-term increase up to + 1200С, however, the maximum pressure is 10 atm. Thus, the operational characteristics are quite comparable with similar parameters of pipes made of cross-linked polyethylene, which we cited above.

The choice depends mainly on the specific features of the water supply system and budget. The price range among pipes, even within the same group, is significant, but PEX-pipes are more often cheaper than metal-plastic ones.

№5.

diameter and length Cross-linked polyethylene pipes are sold in coils of 50, 100 and 200 m. Pipes with a diameter of 40 mm and more are sold in lengths of up to 12 m. Information on material should be printed on the pipe along its entire length ( crosslink type), working temperature, pressure, diameter, date and place of production. For added convenience, some manufacturers put risks on the product every meter.

The choice of pipe diameter depends on the type of pipeline, the water pressure in it, the number of consumers and other parameters. General recommendations on the selection of the diameter are as follows:

• pipes with a diameter of up to 15 mm( 10.1 * 1.1, 14 * 1.5 and others) are suitable for supplying water from the main water pipe to the taps;
• pipes 16 * 2 use for the organization of heat-insulated floors, 16 * 2,2 are suitable for hot water supply and radiator heating. Pipes with a diameter of 16-20 mm can be used as the main pipe for cold and hot water supply of apartments and small private houses;
• pipes of 20-32 mm are suitable for organizing water supply in cottages, are also used for heating, pipes with a diameter of more than 20 mm are usually not used for underfloor heating;
• pipes of 40-50 mm are suitable for a riser in apartment buildings;
• pipes with a diameter of 50-63 mm are used in both heating and water supply systems.

Usually, the manufacturer specifies for what purposes this or that pipe is best, for example, for heating, hot water supply, or it is universal in use.

It is not difficult to calculate the length of the , but for this purpose there must be an exact plan for the water supply system, radiator or floor heating. We measure the length of the proposed pipeline and multiply the resulting value by 1.2 - this is the margin for unforeseen situations that may occur during installation.

№6.Fitting for pipes made of cross-linked polyethylene

Looking ahead, we note that it is better to take the fittings from the same manufacturer as the pipes. Even with the same declared sizes, the difference in the diameter of products from different manufacturers can reach 0.5 mm. In this case, it is difficult to speak of absolute tightness and reliability of the system.

The following types of fittings are used to connect individual pieces of PEX-pipes:

• Compression Plastic Fittings .Consist of body, connecting and sealing rings, clamping nut and clamping ring. Installation is very simple: the pipe is cut at an angle of 90 degrees, all the burrs are removed, the clamping nut and ring are put on, the sealing and compression ring is inserted into the case, inserted into the pipe to the stop, the clamping ring is pulled and the nut is tightened. You can tighten it with your hands or with a tool - the main thing is to tighten the nut firmly. Such fittings do not require any additional tools, but it will be necessary to check the tightening of the nuts every 3-5 months;
• compression metal fittings stronger and more durable than plastic, cost a little more expensive, consist of the same elements. The principle of installation is the same, no special tools, except a wrench, will be needed. Compression fittings can be removed and reused;
• press fittings consist of a body and a crimp coupling, provide maximum strength of the connection. When installing a heating system( floor and radiator) and hot water, it is recommended to use this type of fitting. Such products are more expensive, and their installation requires special expensive equipment( $ 1-2 thousand), so you have to ask for help from professionals. An alternative solution is to rent the equipment, if, of course, you are confident that you will cope with the installation on your own;
• press fittings consist of a body and a press fitting ring. Installation technology is simple, but specific equipment is also required. It costs several times cheaper than what is needed for a press fitting( $ 200-300), but at the same time the strength of the connection is almost the same. The press fittings are still slightly more expensive than press fittings.

It is impossible to weld, solder and glue the seams of pipes made of cross-linked polyethylene.

№7.Manufacturers of pipes made of cross-linked polyethylene

In order to be 100% sure that the pipeline in a couple of years will not have to be repaired, or completely replaced, it is better to take the pipes from a trusted manufacturer who gives a guarantee on all products. Large companies will not risk their reputation and produce low-quality products. So, today on the market of pipes made of cross-linked polyethylene such figured the main manufacturers of :

• Rehau , Germany. These pipes are considered the benchmark for quality, but they are also expensive. The manufacturer offers a wide range of pipes of different diameters, a huge selection of fittings. In this regard, the company's products confidently ahead of competitors. All pipes are made of cross-linked polyethylene of type PEX-A, and are covered with an oxygen protective layer of ethylene vinyl alcohol( EVAL) on top. The company produces pipes of several series, you can distinguish them by color. In the assortment there are products suitable for organizing cold and hot water supply, heating. The manufacturer says about the special strength and reliability, says that the service life of pipes for about 50 years, and without fear they can be laid under the screed and plaster;
• Uponor , Germany. The pipes are made of cross-linked polyethylene of the type PEX-A, the products are characterized by increased flexibility and durability( about 50 years).Suitable for installation of any type of pipelines, incl.for the hidden laying;
• BIR PEX , Russia. Produces PEX-B type pipes. The products are distinguished by an affordable price and high quality, the company takes into account the peculiarities of domestic conditions, so the pipes are ideal for arranging heating and water supply systems. The manufacturer uses high-quality English equipment;
• Valtec , Italy. The company manufactures PEX-B cross-linked polyethylene pipes. According to the company, this type of cross-linking is optimal, since a reliable uniform connection of the individual polymer chains is ensured, while the cost of production remains affordable for most consumers. Pipes are suitable for arranging underfloor heating, hot and cold water supply, radiator heating;
• Frankische , Germany. It produces PEX-A pipes with excellent performance, but the company's products have not found much distribution in the domestic market;
• SANEXT , Russia. A large company produces everything necessary for the heating system. PEX-A pipes with an EVOH anti-diffusion barrier are also in stock. The products are universal, suitable for heating and water supply, diameter from 16 to 63 mm;
• Rostherm , Russia. It manufactures PEX-B type universal pipes, as well as fittings and a huge range of equipment for heating and water supply systems;
• KAN-therm , Germany. It produces PEX-C and Pert pipes, all products receive a protective coating to withstand the passage of oxygen;
• Watts , Germany. The company manufactures PEX-B type pipes of various diameters. Products can be applied in various systems;
• Tiemme , Italy. The manufacturer manufactures PEX-B type pipes of different diameters, claims longevity at 50 years.

Most manufacturers specify transcendental warranty periods, these are 20-30 years, and somewhere even all 50. The conditions of this warranty must be carefully studied so that during installation and operation they do not violate them, otherwise the manufacturer will have the right not to fulfill its obligations.