Fans by Fantech Electronic Catalogue

2016

C-3

AXIAL FLOW FANS PERFORMANCE DATA

AXIAL FLOW FANS GENERAL INFORMATION

PERFORMANCE VARIATIONS

The achieved fan performances can differ from the test performances shown on the

subsequent pages due to two main effects:-

a) The encroachment of irregular or abrupt changes within the system close to the fan.

If good design practice is followed, then the fan will

receive nearly uniform air into its inlet, and discharge its

air flow in an almost ideal pattern. If this is achieved the

fan will perform to its expected level.

Reference to the "Do's and Don'ts" tips on page

P-1

will

assist in avoiding pitfalls. The advice in "Do's and Don'ts"

applies to the application of all fans, not just axial flow

fans.

b) Changes to the internal elements of the fan: e.g. large

junction boxes on motors, belt drive stacks or excessive

blade tip clearances.

FORMS OF RUNNING

The main series of tests were conducted on Form B units and comparative tests were

carried out on Form A units. Resultant performance differences occur mainly on the

outlet side of the fan, as correct practice should result in the presence of a duct or inlet

cone on the fan inlet.

DOWN-STREAM GUIDE VANES

A normal axial flow fan, whilst being very economical and

compact, imparts motion to the air in an axial and

rotational direction. The rotating component is usually

called ‘swirl’. The swirl component eventually dissipates,

but by using Down Stream Guide Vanes (DSGV) it can be

converted to more useful static pressure. Static pressure

increases of 10%-25% can be achieved with DSGVs, thus

giving an increase in efficiency. As the work is done after

the air leaves the fan, DSGVs do not require any

additional fan power. They are most effective at pitch

angles over 20° and produce small increase in sound

levels of 1-2dB.

Normal

operating

range