Plano-oval (or oval) ducts are controversial among ventilation professionals. Some say that this is the best alternative, others argue that flat oval ducts will not be widespread in the future.
In the meantime, there is controversy, new manufacturers of «ovals» appear, and these products are gradually occupying their niche in the ventilation products market.
Currently, in the construction of buildings, air ducts of round, rectangular and flat-oval sections are used. Round ones are rightfully recognized as the most effective. They have the least air resistance and, consequently, less pressure loss. In addition, round ducts are cheaper than rectangular and flat-oval products. Rectangular ducts are less efficient, but due to their compactness, their use is widespread in the construction of buildings. Flat-oval air ducts are the least common, while they surpass both rectangular and round air ducts in certain parameters.
Flat-oval air ducts are produced on special equipment from spirally wound round air ducts. The material used is galvanized steel. The machine gives round air ducts a flat oval shape by stretching spiral pipes to a flat oval shape with specified dimensions.
If we compare the efficiency of round and flat oval air ducts, traditional round air ducts will take the lead. But it is worth remembering that, despite the significant pressure loss in rectangular ducts, they often replace round ones due to their more compact placement in space. Flat-oval air ducts, in addition to being able to be compactly placed where round air ducts take up too much space, are more efficient than rectangular ones. Air pressure losses in flat oval ducts are significantly lower due to rounded corners and less turbulence of air flows in the duct.
In addition, the appearance of flat oval air ducts surpasses both of its «competitors», which makes them especially valuable when placed outdoors in space.
In addition to the obvious advantage of flat oval ducts — their higher efficiency compared to rectangular ducts, there are other reasons why flat oval ducts can replace the «rectangular»:
The absence of internal corners in flat oval ducts solves the problem of plaque accumulation that occurs at the bends of rectangular ducts;
The use of a nipple connection simplifies the installation process of the system and makes it cheaper, and also facilitates the design, provides high tightness;
When installing flat oval ducts, it is possible to use the space that is required to accommodate the connecting flanges of rectangular ducts, therefore, the system takes up less space.
The maximum length of the duct is 6 meters. This simplifies the process of assembling long straight sections of the system and makes it more airtight due to fewer joints. Rectangular sections have a maximum length of 1.5 meters.
The issue of including equipment in a system of flat-oval air ducts is solved by the ability to use a variety of transitions from a flat-oval section to a circle and a rectangle.
Despite the obvious advantages, flat oval ducts are not in demand enough on the market. Manufacturers do not develop this direction, since there are practically no flat-oval elements in the projects. Designers, in turn, do not include “flat ovals” in their projects, since few enterprises are engaged in the production of flat ovals. At the same time, both of them forget that a flat-oval system, with a competent approach, corresponds to the main rule of ventilation — the maximum efficiency of the system at its minimum cost (in conditions where it is impossible to use a system of round air ducts).
The article was prepared by specialists of the Bastion ventilation plant, a manufacturer of flat oval air ducts.