Pros and cons of pumping of tires by nitrogen

Inflating the tires with nitrogen – a relatively new service for motorists. In Europe and the United States for commercial vehicles and buses used exactly this way. And it is not a requirement of the rules of operation, and the choice of the owners themselves.
This trend is likely to have roots in the Formula 1 races. That wheel racing cars first began to fill with nitrogen (more nitrogen-air mixture). This technical regulation allows fill racing wheel as nitrogen and normal air.
In this respect, between motorists consensus yet. Manufacturers of nitrogen gas generators and stations, that offer this service, of course, paint the advantages of nitrogen for tire inflation. On the other hand, many experts call this service simply pumping money from unsuspecting motorists. To find out who is right, it is necessary to consider the arguments of both sides.
From school, we know that the air consists mainly of nitrogen (78%) and oxygen (20%). The remaining 2% is a small amount of carbon dioxide, water vapor and other gases. Modern nitrogen generators for pumping tires allow to achieve 95% of the nitrogen content. Are these significant additional interest for the performance?
The main advantage of using a mixture of nitrogen tire inflation is considered to be increased safety. The reason is as follows.When the temperature change in the tire pressure is changed proportional to the coefficient of thermal expansion. The value of this ratio for nitrogen is seven times less than for oxygen.
During the movement, the pressure in the preheated tire can be increased by 0.4 – 0.7 atmosphere that is quite noticeable and sometimes results in damage to the tires, especially in summer. But can we say that should be divided into seven injection of pure nitrogen at these figures? Of course not!
Please note that in accordance with the law Mendeleev-Clapeyron there is a relationship between the temperature, volume and pressure of an ideal gas. Nitrogen and oxygen begin to behave differently only at pressures of several MPa.
That is, during normal operation of the difference in pressure at an acceptable heating the tires will be a few thousandths of an atmosphere that can not always be noticed even in the laboratory. The larger the wheel itself and the pressure therein is higher the more pronounced will be the beneficial effect of the use of nitrogen.
As a second important advantage is stated that nitrogen leak from the tire occurs not because of the fact that the molecule is bigger than the oxygen molecule which penetrates rubber pores faster. With this hard to argue, as the diameter of the nitrogen molecule is really greater than the diameter of the oxygen molecule by almost 7%. In absolute terms – it is 0.02 nm.
In practice, a mixture of air leakage at the leaking nitrogen 0.5 atm be 0.47 atmospheres. In this case, the content of nitrogen in tires with additional normal air will only increase, because by this logic, mainly because the bus passes a leak of oxygen molecules.
A third factor in favor of nitrogen associated with its chemical properties. Nitrogen reduces corrosion and aging tire materials, as opposed to oxygen it very slowly reacts and nitrogen mixture used contains much less particulate contaminants and corrosive than ordinary air, which is fed by a simple compressor.
Without a doubt, a tire that is inflated with nitrogen, the inside is destroyed much more slowly. With this, by the way, no one disputes. But what it gives to the car owner? What is the main cause of damage to the tires? Oxidation by oxygen or air cord aging of rubber on the inner side? Of course not! The main attack takes on the outside tire. The aggressive environment in the road surface and mechanical damage – these are the main causes of failure of the tires.
Another advantage is called the reduction of the wheel mass, which is also evident, since nitrogen has a lower specific gravity of 3.2%. What are the benefits in absolute terms? It appears, about 7 grams on each wheel! A lot or a little – it’s up to the car owner.
There are also myths associated with the use of nitrogen. For example, the tire does not overheat nitrogen. In fact, the value of heat transfer from oxygen somewhat higher. Although when trying to figure out these values, we come to be so small differences that are not recorded by conventional measuring instruments.
From car owners can also be heard, that the replacement of old buses with new ones uploaded nitrogen, they not only become much less to lose pressure, but also the course of the machine became softer.
A marked decrease in the pressure loss in RV in this case is obviously connected not with nitrogen, using a new tire. A stroke softness and reduced vibration noise usually due to the fact that by pumping nitrogen wheel pressure is reduced to a couple tenths of an atmosphere, which can be determined simply by using a different gauge.
After weighing all the pros and cons, it can be argued that the pumping of tires by nitrogen is definitely its advantages, which, however, are much more modest than that advertised.
Lack of nitrogen use in tires one – price. The cost of this service is twenty times higher than normal pumping wheels.Therefore, every motorist can safely make their own decisions. Worst of nitrogen will not be exact, but also expect a major improvement is not worth it.

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