The world of concrete vibration
In this article, the President of ENAR presents and explains the 3 models of concrete vibrators that exist in the current market.
The different vibrators to satisfy the needs of the 5 continents.
When our customers speak or ask us about concrete vibrators, an enormous disparity is observed between the concepts with which the different types of vibration are designated and between the different devices used for this.
It must be borne in mind that the market that ENAR serves covers the five continents and therefore it is understandable that the concepts and meanings can be very different, depending on whether a customer from South America, India or Europe is speaking.
With the purpose of unifying the terms used, I have listed below the different models I have been able to find in the more than sixty countries that I have visited, trying to promote our products.
3 types of vibrators for concrete
Basically, there are three types of vibrators. The difference between each one of them corresponds to a different way of moving the eccentric that produces the vibration.
Concrete vibrators moved by compressed air.
This type of vibrator can incorporate a small pneumatic motor or a system that, utilizing pressure, causes a mass to move.
They have been used very much as in construction sites there is usually a compressor, but since electric power began to be installed at the beginning of projects, its use has been greatly restricted to special cases.
Vibrators moved by a flexible shaft
In the last decade, it has been the system with greatest acceptance and the most appreciated in the world of concrete vibration.
Its system consists of connecting an eccentric at one end and at the other end applying the power from an electric motor or from an internal combustion engine. These types of vibrators reach a speed of around 11,000 r.p.m.
If the flexible shaft is caused to rotate at a speed of approximately 3,000 rpm. the vibrating needle (or bottle, or head, depending on the country) a device must be incorporated that multiplies the speed (frequency) to the recommended 11,000 rpm.
This is achieved by the connection to the end of the shaft of a mass like a pendulum which, when rotating inside the needle, produces a vibratory movement of greater frequency.
Because the latter is a very simple mechanism, it is cheaper and therefore, it is the most used. It is supplied from several countries, but it is China that produces a very high percentage of those used.
Due to the disadvantages of loss of speed when the concrete is hard, of difficulty in its operation and due to the lower quality which almost all these devices usually have, its use is decreasing drastically and is restricted to zones with low purchasing power or low requirements in the works.
Electrical concrete vibrators.
The latter models are costlier to acquire, but their features, ease and comfort of use, power and reliability make them much more profitable when the entire lifetime of the concrete vibrator is considered.
How do they work? The eccentric of the needle is caused to rotate by an electric motor that the needle carried incorporated.
By this system, the flexible shaft is eliminated, and with it, the breakdowns that are so common and so expensive inherent to these models.
To obtain the repeated 11,000 rpm the motor must be powered by a current of higher frequency than is normal.
Normally a converter transforms the characteristics of the grid current up to 200 Hertz and 42 volts. This current is called high frequency, and from this it is derived that these vibrators are called “high frequency”.
It must be noted that this term is used erroneously in many countries for flexible shaft vibrators. Normally they are called this by users who do not know the authentic high frequency vibrators.
In Europe they represent more than 70 % of the equipment in use and their use continues to extend, causing us to suspect that in the future they will be the ones most in demand in the rest of the world.
More than 15 different types of concrete vibrators.
At ENAR Group work is carried out in research and innovation for concrete vibration, providing the best offer of vibrators in the three systems, and I believe that there is no brand in the entire world that manufactures as many models as our catalogue offers.
It should be emphasized that ENAR high frequency vibrators are our distinction of the company surpassing all our competitors and providing to the world of vibration the improvement and perfection that it deserves.