About Induced Draft(ID) and Forced Draft (FD) Industrial Process Fans
                     About Induced Draft(ID) 
and Forced Draft (FD) 
Industrial Process Fans
Jenny Knight
Writes for 
Small and Medium Business Corner & 
SMB Corner
Among the varied types of process fans that are used in manufacturing units, 
we also have draft fans. The draft fans are further subdivided into two more 
categories: ID fans and FD fans. This article is going to elaborate upon the 
primary features of both these fans.
•An ID fan collects the flue gases having high temperatures that are 
present in furnaces/boilers and expels them into the outside 
environment. As a result, negative pressure gets generated within the 
systems. On the other hand, an FD fan brings in air from the external 
atmosphere and this leads to the generation of positive pressure. The 
pressure makes sure that the combustion process gets completed 
smoothly.
•An ID fan is fixed in the area that is in the middle of the chimney and 
dust collector. And, an FD fan is installed at the boiler’s inlet, from where 
it is enabled to push outside air into the system. In factories where coal 
is the primary fuel of the combustion process, forced draft variants are of 
immense value. Here, they are put to use as both primary and 
secondary fans.
•For cost savings, the ID fans and FD fans are equally efficient. The 
power consumed by these fans is quite low when compared with other 
kinds of process fans.
•The FD fan is way ahead of its ID counterpart, in terms of reducing the 
cost of maintenance. Likewise, a forced draft fan is always tidier than an 
ID fan.
•As ID fans are continuously exposed to extremely hot flue gases, they 
develop many issues related to erosion and corrosion. But, there are no 
such problems when we consider the FD fans.
•Even though the basic working of an ID blower and an FD blower is 
different from each other, there is one common aspect. Both the ID fan 
and FD fan work in such a way that the boiler’s air system balance is 
consistently appropriate.
•There is one more unique aspect that sets apart the ID fans and the 
forced draft ones from other kinds of fans. Both these varieties ensure 
that the life of an impeller gets substantially extended. And, this brings 
about a marked decline in the costs of maintenance.
•Similarly, the ID and FD fans are much better than other blowers in 
terms of supporting a long life of bearings.
•Another characteristic of draft fans is worthy of special mention. The FD 
fans and ID fans emit minimal noise while running and this contributes to 
bringing down sound pollution. When sound pollution is within the limits, 
there is a noteworthy improvement in the working environment. The 
workers would then be able to put in more effort and enhance 
productivity.
Generally, any FD fan/ID fan is sold with an excellent, customer-friendly after-
sale service policy. Therefore, even if a manufacturing plant faces any technical 
issues with the fans bought, there is no need to worry. The only thing that has 
to be made sure of is that the blowers are bought from sellers/manufacturers 
with a proven track record. This is in terms of providing flawless after-sales 
service.
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