Bellows for water: what is it and how to choose?

Not so long ago, the connection of faucets and mixers to the water supply system was carried out using threaded fixation of rigid pipes and welding. But with the advent of the bellows, the installation technologies have changed, and the modern consumer has begun to switch to soft nozzles.

Bellows pipelines for water are presented in the form of corrugated hoses made of stainless steel AISI 304. Products can have a welded or seamless design with wall thickness not exceeding 0.3 mm. The hoses are equipped with brass, steel or bronze cap nuts, coated with nickel or chrome.

Extreme 2-3 corrugations roll, which ensures reliable fixing of the nuts and tight connection. Each tube is equipped with a retaining ring, which is responsible for the tight fit of the seals and folds to the pipe and fitting.Adapters are used to connect to the pipeline with a larger or smaller diameter.

Their reliability and durability bellows liners are required to the material from which they are made. Steel is highly resistant to corrosive processes, well tolerates the effects of acids, aggressive chemical compounds and is characterized by increased endurance to sudden pressure and temperature drops. Due to these qualities, steel products can serve 20 years or more and have the ability to withstand temperatures from -40 to 250 degrees. The operating pressure of the bellows type depends on the size of the cross section and the wall thickness, but varies on average from 1.5 to 3 MPa.

Each model is equipped with a gasket, which can be made of paronite, copper or fluorine-containing polymer. Due to the fact that the seals are under serious stress, their thickness corresponds to 2.5 mm. Due to the high tightness and reliability of the connection bellows linings are often used to connect to gas mains. In order not to confuse gas pipes with water pipes, the first ones are painted in bright yellow color.

Leads can also be used when arranging heating systems to connect radiators to the main riser. This is possible due to the high temperature stability of products capable of withstanding temperatures up to 250 and sometimes 300 degrees. For comparison: rubber-reinforced models are designed for heat loads up to 120 degrees, and flexible PVC hoses - by 60 ° C.

Bellows are released in several sizes, which are calculated in inches and denote the absolute size of the internal section of the nuts, excluding threaded furrows. The most popular sizes in everyday life are 1/2, 3/4 and 2 inches. All the performance data of the supply lines, as well as the marking of the steel from which they are made, are indicated in the product passport, which is attached to each package and can be presented by sellers at the request of the buyer.

High consumer demand and popularity of bellows due to a number of undeniable advantages of these products:

• Increased resistance to oxygen diffusion allows hoses to withstand severe loads resulting from high pressure in the network.
• Full fire resistance and environmental safety models allow you to use them in residential buildings and public spaces without restrictions.
• Increased wear resistance and long service life distinguish bellows liners from other types of hoses and nozzles used for water liner.
• The ability of the eyeliner to hold the same pressure over the entire length is due to the preservation of the working section of the tube even during its strong bending.

• The ability to install as compensators on polymer pipelines significantly expands the scope of application of products.
• High resistance to hydraulic shocks of the water supply network and the ability to dampen vibrations make it possible to use liners in compressors and other mechanisms subject to vibration and shock loads.
• Wide scope. In addition to connecting to the plumbing, heating and gas networks, bellows liners are used for the installation of air conditioners, fire extinguishing systems and a variety of sprinklers, as well as for removing steam and building industrial equipment that works with oil refineries and toxic chemicals.

Used eyeliner and in the food industry, carrying the flow of solids, beverages and other liquids. In everyday life, using liners, connect washing and dishwashers, shower cubicles and faucets.

The disadvantages of liner include lower flexibility in comparison with rubber hoses, which sometimes complicates installation in confined spaces. For example, under a small and narrow sink with a close location of the main water pipe and mixer, it will be rather difficult to install a corrugated liner.

However, under certain conditions, this disadvantage easily passes into dignity, since, thanks to its elasticity, the hose is capable of maintaining and retaining its shape without the aid of additional structures.

In the modern market of plumbing seamless liner from corrugations are presented in a wide range. Bellows models are classified according to such characteristics as the material for the manufacture of fittings and the functional purpose.

Fittings are located at both ends of the hose, they are responsible for connecting it to the point of consumption and can be made of brass, stainless and carbon steel:

• Brass connectors differ in high resistance to corrosion and low cost. The downside of such parts is the need to replace them every five years. This is due to the feature design details. The fact is that brass is not a material suitable for welding, therefore its fixing on the ends of a metal hose occurs by means of soldering. Soldering is much inferior in the fortress of welded seams and under the influence of high temperatures quickly becomes useless.

• Stainless Steel Fittings are the best option and will be able to serve up to one hundred years. The material copes with vibration loads and thermal expansion, so it can be used in systems with high pressure and serious temperatures. The only drawback of steel products is the high price compared to brass fittings.
• Carbon Steel Fittings in their performance characteristics are significantly inferior to brass and stainless steel products.Parts are subject to corrosion and oxidize under the influence of moisture. The advantages are low cost models and a sufficiently long service life, reaching 25 years.

Functionally, bellows connections are divided into water, gas and universal.

The modern market of sanitary products offers a large number of bellows liners manufactured at enterprises of different countries.

However, the most famous manufacturers are German and Italian companies.

1. Concern from Italy Idrosapiens well known all over the world. The company is engaged in the production of pipes, connections, hoses and other sanitary products, and due to its high quality and wide range it occupies one of the leading positions in the market. Attention consumers are offered bellows of all kinds, capable of withstanding serious loads and featuring an attractive appearance.
2. Company Witzenmann GmbH from Germany, along with the classical models, it represents reinforced versions capable of withstanding network pressure up to 21 MPa and used in industrial installations. Household liners produced by the company have a large number of positive reviews and are of high quality and reasonable price.
3. Italian products Emiflex S. p. A. also in high demand. The models feature a beautiful chrome body and high-quality steel fittings. The disadvantage of products is too high for the Russian consumer price.

Among domestic manufacturers, we can distinguish such companies as Aquatekhnika, Monolith and Fleximiline, which produce inexpensive but at the same time sufficiently high-quality products.

• When choosing a bellows connection, you must be guided by the matching of the inlet fittings with the connected device without the use of auxiliary adapters. There is a large number of hoses with fittings and nuts of different diameters, so it is easy to choose the appropriate size.
• In addition, the purchased liner must match the temperature and pressure inside the system. To determine the purpose of a particular model, you can use the color marking, which is on the stretch braid of the product. For cold running water you need to purchase a model with a blue flag, and for a hot one with a red flag. There are also universal eyeliners that can work with both hot and cold water. They have two-color marking.

• If the model is chosen to connect the kitchen sink mixer, where the distance from the main pipe to the base of the faucet is minimal, it is better to purchase a more flexible copy. To do this, take several samples and hold them at one end in a horizontal position. You need to buy the hose, the bending angle of which will be maximum. It is necessary to pay attention to visible defects. So, products with low-quality compression of the braid near the output fittings, as well as models damaged by corrosion in conjunction with rigid gaskets should not be bought.
• When choosing the length of the liner, it is recommended to add a few centimeters to the distance between the pipeline and the device.This requirement is due to the fact that when connecting the hose should not be stretched between two points: in this case, moderate sagging is appropriate. This will reduce the noise arising from the movement of water inside the liner, and ensure a comfortable stay in the bathroom.

Bellows do not require special care and specialized service.

To increase the service life and normal operation of hoses, you should follow some rules:

• Half an hour after installing the eyeliner, you should check both connections with a dry cloth. In the event of a leak, it is recommended to immediately eliminate it, tightening the captive nuts, but at the same time, avoiding excessive clamping of the gasket.
• It is desirable that the threaded connection of the fitting for the pipe and pipe consist of the same alloys. This will help prevent electrochemical corrosion and extend the service life of the hoses.

• Usually, the maximum allowed bending radius of the bellows is prescribed in the passport of the product and should not be allowed to decrease.
• At installation of an eyeliner it is impossible to twist and excessively stretch a hose.This can cause a violation of the integrity of the walls, and damaged bellows are not repairable, so you have to change the liner entirely.

How to choose a bellows for water, see the next video.