Complex ventilation and air conditioning systems are designed taking into account many factors. Subsequent installation requires special attention: air ducts, air heaters, silencers, diffusers, grilles and valves must be in place, and fans and air conditioners must have the appropriate power.
A fan, centrifugal or axial, can generally be called the heart of the system, because it is he who pushes air through the vessels of the system - ducts in the right direction. Despite the fact that such units are necessary to perform the same function - the forced movement of air, each of them has a special design.
Centrifugal fan. Device, principle of operation and distinctive features
This equipment consists of an impeller, which is mounted on a special shaft, inlet and discharge pipe and spiral housing. Air (transported gas) is absorbed by the manifold and, falling into the fan housing, is captured by the blades of a rotating wheel. Thus, there is a change in the direction of the air flow (gas) itself: from a
direct, parallel axis, it becomes radial. Further, the acting
centrifugal force propels air through a special hole in the casing.
Such features of the operation of this unit became the reason for its name - the centrifugal fan, it is also radial. Another "nickname" - the snail - this equipment has received thanks to its spiral-shaped casing.
The rotation of the impeller in such a fan can be right or left. The number of blades affects the type and purpose of the equipment. There is another nuance: in which direction the blades themselves are bent (forward or backward) - this in some cases is of fundamental importance. For example, a centrifugal fan equipped with vanes bent backwards can save up to 20% of electricity, and during its operation, overloads in air flow are permissible.
The blades bent forward, in turn, can reduce the diameter of the wheel to which they are attached, and accordingly, the fan itself can be more compact. Another plus: the speed is lower, and the noise level is reduced.
The centrifugal fan can be used in the installation of forced draft systems for canteens and laundries, in the metallurgical and chemical industries, and in oil refineries. It should be borne in mind that if you plan to move relatively clean, not contaminated with harmful impurities, then a “snail” made of carbon steel is enough. In cases where explosive gases are present, equipment with a casing of aluminum alloy or cast iron is used. In enterprises where there is a need for venting air containing impurities of gases or aggressive vapors, it is recommended to install special fans. Their distinctive feature is that the inside through which dangerous air will flow (impeller with blades, casing, shaft) are made of acid-resistant alloys of steel, plastic and aluminum. It is quite obvious that if specific equipment is needed for
the ventilation device, in particular, a centrifugal fan, its price will be higher than the standard carbon steel one.