Polymer and composite materials, due to the ease of processing and the ability to give them the desired properties, are actively included in any technological field of activity. There are new materials in construction, especially in the field of “small engineering”. One of such materials is polyvinyl chloride, and many other plastics. Gradually, plastic ventilation comes to replace ventilation systems made from traditional materials.
The advantages of using plastic in ventilation systems
For any pipe communications, including for ventilation ducts, air ducts and ducts, during construction were usually used:
- Concrete, as the most reliable and inert to the environment.
- Asbestos, as the most easy to process.
- Metal, which with its strength makes it easy to give details of any shape.
However, concrete and asbestos are brittle, and have a non-linear thermal coefficient of expansion, which leads to rapid temperature destruction. Metal is expensive and too heavy, but in all other ways it is ideal if the environment is non-aggressive.
In modern household ventilation systems, it is still impossible to completely eliminate metal, however, with the advent of cheap and environmentally resistant polymeric materials, plastic pipes for ventilation snatch a share in communications from 10 to 20%.
Good to know! Many people believe that plastic is ideally impermeable, flexible and durable, but this is true only in laboratory conditions. Under the influence of the environment, microcracks form in the plastic, which expand when temperature drops – polymer fibers break, and plastic ventilation ducts gradually become brittle and fragile.
There are several types of modern plastics:
- Polyvinyl chloride (PVC).
Each has its own advantages and almost all have one single flaw.
This is the cheapest, lightweight and durable option, easily processed both industrially and at home. Under normal climatic conditions, it is practically eternal and harmless: it decomposes, if not hundreds, then certainly decades, so that the ventilation ducts and various products from it will survive the house itself.
But there is one hard restriction in use. This plastic contains chlorine, and the decomposition temperature of PVC (160-180 ° C) is lower than the plasticity temperature (200-220 ° C). Therefore, it cannot be formed with the help of a burner and, especially, to apply where relatively high temperatures are used.
Important! In everyday life, steam can easily reach a temperature of 200? C, that is, the use of plastic ducts for ventilation from PVC in the sauna is clearly excluded.
The decomposition will produce chlorine compounds and, above all, HCl. This gas with moisture forms the actual hydrochloric acid, so it is dangerous for the eyes and the respiratory tract, although in all other respects it is simply unpleasant or almost imperceptible.
Thus, polyvinyl chloride is an ideal plastic for ventilation, partially excluding the kitchen, water heater, fireplace, and those places where temperatures above 120 ° C may occur (it is believed that this is the “top bar” for human security).
This plastic is not much different from PVC, but it can withstand temperatures up to 280 ° C without any problems. At temperatures above, decomposition begins, releasing more nitrogen compounds, which is much more dangerous than chlorine compounds.
A relative disadvantage is its high cost, but it combines two seemingly incompatible factors: plasticity and durability. The ductility of polyurethanes exceeds the resistance of granite and steel to fracture stresses. The finished product made of polyurethane can be bent an infinite number of times – it will not crack and retain its initial shape as soon as the voltage is gone.
Polyurethane is ideal for household temperature parts, especially where shifts and distortions are possible: coupling rings, all kinds of connections and areas where there may be a high household temperature.
This plastic is ideal for molding. Already at 180 ° C, it is surprisingly plastic, so that any pipe can be twisted even just in a hot steam, and the torch can be bent at any angle. At the same time, it is durable, and at high temperatures itself does not emit anything dangerous (impurity dyes or special additives may be dangerous). It is in the middle price category, but sufficient to make it not only the components of plastic ventilation systems, but also heating batteries.
Polypropylene is a relatively expensive but versatile safe plastic.
Interesting! Recently, the ABS / PLA family of plastics, which is used for 3D printers, is gaining popularity. For domestic use, these plastics are absolutely safe, and with the help of a printer you can independently make all non-standard parts. Including those that use plastic ventilation: from “turn signals” with non-standard angles to components like valves.
After the boom of plastic windows, almost the entire industry began to use polyvinyl chloride for any pipes and parts of plastic ventilation (round and rectangular), replacing metal wherever possible. Accordingly, grilles, branch pipes, adapters, rings and pipes and ducts of any sizes and sections, both round and rectangular, can be found everywhere. They are mounted with their own hands in minutes and in fact simplify the installation of even the most complex ventilation systems.
Types of ventilation, advantages and disadvantages of ventilation systems, their device.
Value and types, advantages and disadvantages, basic parameters, the main components of ventilation systems.
PVC can be used anywhere except (partially) in two zones: a kitchen and a fireplace / water heater. Since in the kitchen you can turn on all the hotplates to the maximum at once, it is simply impossible to predict the temperature of the air entering the hood. The air itself has a microscopic heat capacity, but a couple of hours of frying may well warm up the plastic drain to a critical temperature. It is better to use the longest possible metal outlet – the longer, the better, since the metal will easily give off heat to the room air and the acceptable temperature of the output stream will reach the plastic. For the arrangement of the exhaust hood, you can use only metal.
In the case of a water heater, you can get by with a small length of metal pipe, and then with plastic. This is convenient for the primary condensate to settle on the metal and flow back, and then the steam is no longer dangerous for PVC, since the temperature of boiling water and steam will not exceed 100 ° C.
However, there are pressure water heaters that are used for mini-saunas. Here the use of any plastic is excluded, even polyurethane, which simply “will flow”.
In all other details, you can use PVC with complete impunity: pipes, ducts, valves, grilles for valves. The sections and dimensions of plastic pipes for ventilation are reduced to several generally accepted standards. Just do not try using a burner to form, for example, a bent pipe. It is better to buy an extra adapter.
Output valves that use fans, as well as plastic grilles for ventilation, are sold in several standard sizes, so the choice of plastic ventilation parts of rectangular or circular cross section more closely resembles the selection of children’s designer parts. Since the PVC pipe can be cut even with a knife, the entire installation of the system will be reduced to going to the store.
This method involves the use of high-power fans, recuperators, heaters and other sources of vibration and temperature extremes.
All these devices, especially those that come in contact with plastic air ducts for ventilation in the kitchen, are best connected through small sections of metal pipes, the interfaces of which with plastic must be securely fastened. Plastic, due to constant exposure to temperature changes and vibrations, becomes brittle: polymer fibers break, and in order for them to “bond” again, a viscosity temperature is required.
Unlike polyurethane and polypropylene, with PVC this “number will not pass” – the viscosity of PVC is higher than the decomposition temperature, so a couple of minutes of warming up with a gas mini-burner will not work. After a few years it will be useful to change those sections of pipes that are directly connected to the equipment of an active plastic ventilation system.
Plastic windows have special requirements for the ventilation system. The simplest ventilation system is natural channelless, in which air circulation in the room is ensured by opening the window, transom or window entirely. However, this method is too expensive for middle and northern latitudes, especially in the cold season.
A more correct approach in this case is to use a ventilation valve for plastic windows. This device is mounted horizontally at the top of a plastic window and can be installed with your own hands. It will take a few simple tools: a screwdriver, tape measure, stationery cutter and the valve itself.
The main advantages of using a ventilation valve for plastic windows:
- natural flow of air into the room is restored;
- no drafts appear;
- sound insulation is not broken;
- the light aperture does not decrease.
It is much easier to arrange ventilation of plastic windows with your own hands than to install a valve or similar device for wooden or aluminum windows.