Axial Flow Fan By Pasko Engineering (P) Ltd.

A fan consists of a series of radial blades/impellers attached to a central rotating hub. The rotating assembly of blades and hub comprises a fan assembly and it may or may not be enclosed in a housing. Fans are driven by an electric motor to generate airflow through a given system.ImpellerThe impellers of the Pasko fan are tested for simulated aerodynamic loads, load deflection characteristics and the strain at the shank. Pasko Impellers usually have blades with cross-sections matching those of an aerofoil. As compared to curved sheet blades, aerofoil can apply greater force to the air, thereby increasing maximum pressure and can maintain better efficiency over a wider range of volumetric flow. Also by increasing the thickness & curvature of the inner sections, the blades can be made stiffer; this limits flutter and allows the impellers to run at higher speeds.CasingThe casing encloses the impeller and motor assembly completely. Pasko axial flow fan casings are generally rolled and flanged from heavy-gauge mild steel. Flameproof and increased-safety motors are not normally placed outside the casing and can be connected directly to the terminal box in accordance with the requirements for the particular hazardous zone.HubThe design of Pasko fan impeller and hub is based on the worst possible aerodynamic load and centrifugal load scenario. The hub incorporates a system for the adjustment of pitch angle, cleaning or repair of the impellers.FixingsAll impellers are assembled together using high-tensile, zinc-plated bolts and self- locking nuts.BalanceThe balance of impeller assembly complete with the hub is carefully checked to ensure vibration-free running. Both the static & dynamic balance tests are carried out before testing the fan for its performance.Pitch AdjustmentThe blades of Pasko axial-flow fans are often attached to the hubs by a system which allows the pitch angle to be set at any desired value on assembly. This adjustment pitch feature enables the fan to be supplied preset for exactly the volume flow required, eliminating the waste of power.Tip ClearancePasko fan impellers are generally mounted on the shaft extension of the driving system. This is supported in a cylindrical casing surrounding the impeller with the minimum practical running clearance; a typical value for this radial clearance is 0.25% of the impeller diameter.Fan Driving SystemsThe fan assembly could be mounted on a wide range of driving systems to meet the desired range of performances and applications. These includes the following:Direct-driveIn this case, the fan is directly mounted on the motor shaft inside the casing.Belt driveThe belt-driven units are employed for applications where the motor must be placed out of the air stream. Generally, V-belt belts are used by us as the connecting medium.Fan PerformanceThe way Pasko fan impellers (blades or rotors) are designed, the amount of air they can move decreases as the pressure they are working against increases. The airflow vs. pressure information for a particular fan is called the fan performance data. The performance of a fan depends on the size, shape & speed of the impeller. The fan performance data is essential for selecting fans as per the desired airflow and system pressure.Fan Performance CurvesFan performance curves and data show how much pressure and airflow a given fan can produce at a given speed. This data is based on the system resistance (pressure) occurring away from the fan. Fan performance curves are developed by fan manufacturers based on the testing of a prototype fan fabricated based on the theoretical design.ApplicationsThe Pasko axial flow fans are widely used for providing the required airflow for heat & mass transfer operations in various industrial equipment and processes. These include cooling towers for air-conditioning & ventilation, humidifiers in textile mills, air-heat exchangers for various chemical processes, ventilation & exhaust as in mining industry etc. All the major industries use large number of axial flow fans for operations, such as Power generation, Petroleum refining & petrochemicals, Cement, Chemicals & pharmaceuticals.Product Description Impeller diameter : 250 up to 1600 mmCasing thickness : Up to 12 mmImpeller types : Fixed / adjustable pitchMotor frame size : 63 up to 280Casing form : Short/Long casing/Bi furcated.Surface treatment : Primer, finish, hot-dip galvanized, on requestMaterial :Impeller : Corrosion resistant cast aluminiumCasing : Steel, aluminium, special alloysSpecial design : Flame-proof/ corrosion resistant/shock proof. Standard Accessories Inlet coneProtection grillWall cowlFeet for horizontal/vertical positionVibration attenuatorFlexible connectionCounter flangeSilencer