Centrifugal fans displace air radially, thus diverting the direction of air by 90 degree. At a constant speed of fan, centrifugal fan will move constant volume of air and not constant mass of air. Hence it is called as constant volume fan. This can be achieved from centrifugal fans with different construction and design.
Depending on the industrial requirements of airflow rate, volume, and pressure centrifugal fans have been customised to serve industry. Centrifugal fans are named as per the function served by them. They are often referred with different names based on the industrial process they support. While the technical functionality of these fans is same, the design element is changed to support several industrial processes.
An Industrial building is often a closed building. We want an environment inside the building to be comfortable. There are various types of industrial processes going inside the industrial building. These different processes can make the temperature inside the building higher. This extra heat has to be vented out of the building using an external equipments like fans, louvres, gravity vents, heaters.
When a centrifugal fan is to be installed for any industrial process, the airflow requirement has to be determined before considering different fan arrangements to accomplish the desired performance. Fans typically work better when they have optimal size that fits ideally in the designated area, placed in the right location to withstand the operational conditions and have proper drive method to modulate the speed. When considering different centrifugal fan arrangements, the motor will have various placement settings with respect to the drive side of the fan. The fan can use different drive methods, depending on whether the motor is independent of the fan as in belt drive arrangement or motor connected directly to the fan axle or shaft as in direct drive configuration.
The size of the industrial fan is often overlooked when selecting a fan system for a new or replacement industrial application. Generally, industries use oversized fans to accommodate for uncertainties of future requirements. While some moderate oversizing is typically acceptable, choosing an excessively large equipment than the actual system requirement should be avoided. The size of the centrifugal fan should be optimal to the anticipated normal demand where it can operate at maximum efficiency for a given volume of air. Proper sizing of the fans involve determining all aspects of fan efficiency including airflow requirement and system effects at the fan inlet and discharge.
Excessive noise of a fan system can be a serious concern in industries. Higher noise levels caused by the fan systems can disrupt the productivity and cause nuisance to the working environment. The noise generated could be due to the turbulence effect at the fan blades or rotation of the fan shaft or motor. Typically, the noise produced by a centrifugal fan system is dependent on various factors including the fan size, airflow rate and pressure. Fan systems that work at optimum efficiency produce lower noise levels than the fans with inefficient operation. Using over sized fans for industrial applications or operating fans at higher speed produce vibrations, causing higher noise levels. The sources of noise in a centrifugal fan could be due to airborne or structure borne vibration levels. To identify where the issue is being produced and suggest solutions for specific noise issues, it is essential to understand the sources causing the problems.
Centrifugal fans perform the basic functionality of moving air from one place to another. There are several centrifugal fan types and sizes available each with certain application benefits. Since there is a great diversity in fan applications such as drying, cooling, conveying, aerating and ventilation etc the specifications needed for selecting the fan system also vary. A fan with right design and material, chosen by considering process requirement will enable good efficiency and reliability. Proper selection of the fan type is dependent on certain factors like fan type & size, airflow rate, static pressure, density of the air to be moved, system resistance, temperature range, space constraints, material to be handled, variations in operating conditions etc.
Centrifugal / Radial fans offer regulated high pressure airflow that is required for several industrial applications and air pollution systems. Centrifugal fans are constant volume devices and can operate under high sensitive conditions such as high or low temperatures, corrosive gases, acidic fumes etc. There are several ways how a centrifugal fan can be used as a process fan in industries, such as in transporting air/gas, drying, cooling, material handling, air re-circulation etc.
Blowers are used in industries when there is a requirement for larger volumes of air flow at higher pressures. A fan with higher pressure ratio (output pressure / input pressure) can be called as a blower provided it produces pressures as high as 1.20 kg/cm2. Like fan systems, blowers are widely used in industrial processes where a constant flow of air/gas is needed at higher pressures such as conveying material in dust collector systems, combustion air for burners, drying & cooling, general ventilation & circulation of air and so on. Blowers with higher efficiency are also used in industrial vacuum systems where suction or negative pressures are required.
The airflow requirement for an industrial process broadly depend on the operational conditions, material to be handled and system resistance. When airflow of a fan system is not adequate, typically industries seek alternatives such as increasing the fan speed or replacing it with a bigger capacity equipment.
To avoid facing issues associated with system airflow, industries have to ensure proper working of their centrifugal fan system. By employing certain maintenance procedures such as checking fan mechanical conditions and performingperiodicinspection of system components, the issues with system airflow can be rectified.