Fans and Blowers

Categorised by the air movement

Fans and blowers are used to move air from one area to another, to provide or to remove cold, hot, dry or damp air.

Applications are many and varied but the prime purpose is to move a mass of air.

The amount of air to be moved often defines the size of the fan with due consideration of the space envelope available. The type of fan used is sometimes left to tradition, but should be selected by considering the resistance to flow of air likely to be encountered and the shape of the air path required.

Inelco Hunter Ltd have built up many years of experience in Thermal Management and Cooling Solutions, fan and blower applications.

Fans can be categorised into four main types defined by the method of air movement they employ.

Types of Fans and their Function:

	Axial fans High air flow with medium to relatively high pressure build-up The air flow in axial fans, whose blower wheel is similar to that of a propeller, is conducted to a great extent in parallel to the axis of rotation, in other words in the axial direction. Axial fans with free air delivery at zero static pressure have the lowest power input that rises with increasing counter-pressure. Axial fans for the cooling of electronic equipment are mostly equipped with external housing and an electric motor integrated into the fan hub. This compact construction allows space-saving accommodation of all devices; the flange is equipped with mounting holes.
	Mixed Flow / Diagonal fans High flow rate at relatively high pressure At first glance diagonal fans only differ slightly from axial fans. Intake is axial whereas exhaust is diagonal. Due to the conical shape of the wheel and housing the air is pressurised higher. In direct comparison with axial fans of the same size and comparable performance, these fans are distinguished by the lower operating noise.
	Radial fans Limited flow rate at high pressure Many of the cooling problems that occur can be optimally solved by axial and/or diagonal fans. If for example the required cooling air has to be conducted round an angle of 90° or if high pressure is necessary, radial fans are more effective. For your application, ebm-papst offers not only complete radial fans but also motor/blower wheel combinations without external housing.
	Cross flow blower High flow rate at low pressure Cross flow blowers are used above all, for large-surface air flow in appliances. The air flows through the blade roller twice in the radial direction: At the suction point from the outside to the inside and at the exhaust point from the inside to the outside. Whirls form in the roller due to the vanes which guarantee a steady flow of air through the blower wheel.

Fan controls are available in many technologies, variable voltage, variable frequency and EC control.