Mechanical ventilation equipment includes fans, compressors, and injectors. Fans are the most common and important type and can be centrifugal, axial flow, or mixed flow. Centrifugal fans draw air into a rotating impeller and discharge it radially. Axial fans consist of an impeller with disc or airfoil shaped blades that move air axially. Compressors are similar to high pressure fans and can be centrifugal, axial flow, or positive displacement blowers. Injectors use compressed air to entrain ambient air through kinetic energy transfer.

1. Classification of Mechanical
Ventilation Equipment
Muhammad Adil
Final Year Student
13pwmin0689

2. Classification of Mechanical ventilation
Equipment
• Mechanical Ventilation devices include all
powered machines used to induce air flow in
mine openings or ducts.
• Fans are the most important and most
common of these machines, but compressors
and injectors also have application to
ventilation.

3. Fans
• Centrifugal
• Axial Flow
• Mixed Flow
Compressors
• Centrifugal
• Axial Flow
• Positive
displacement
Injectors
• Cylindrical
• Conical
• Venturi

4. Fans
• A FAN is an air pump, a machine which creates
a pressure difference in a duct or air way and
thus causes air flow.
• In a steady flow process, the air pump or
pressure source receives air at some intake
pressure and discharges it at higher pressure.
• The Fan is a converter of energy (from
mechanical to fluid).

5. Categories of Fans
1) Centrifugal Fans: In centrifugal fans the air is
drawn into a rotating impeller and discharged
radially into an expanding scroll casing.
Further divided into:
1) Steel plate
2) Multiblade

6. Centrifugal Fan

7. Axial Air Flow Fan
• Axial Air Flow Fans are classified in two types,
both consisting of an impeller in a cylindrical
housing mounting disc or air foil shaped
blades to cause air flow through the fan in an
axial direction.
• Axial flow mine fans up to 209 in diameter and
5000 hp are in use.

8. Axial Air flow fan

9. Mixed flow type
• The mixed flow type has the appearance of an
axial flow fan flaring in the direction of air
flow and mounting blades on the impeller
whose shape resembles a cross between
centrifugal and axial flow types.
• This type has limited use.

10. Compressors
• Compressors for ventilation use may be
thought of as high pressure fans, since they
also perform as air pumps in the ventilation
system.

11. Compressor types
• Centrifugal and Axial flow compressors:
– Centrifugal and axial flow compressors resemble
fans of the corresponding classes.
– They handle smaller volumes of air at much higher
pressures than fans.

12. Compressor types
• Positive Blowers:
– Positive blowers have two rotating impellors
which mesh in such a way as to cause displacment
of a nearly fixed volume of air (in all other
mechanical ventilation devices, the volume of air
discharge varies with the pressure).

13. Positive Blowers

14. Injectors
• Injectors utilize the kinetic energy of
compressed air to entrain ambient air,
imparting to it mainly kinetic energy.
• Injectors direct a jet of compressed air into
the open end of a short pipe section or
ventilation duct, entraining the ambient air,
and introducing an air flow.
• The Characteristics of the injector depends
upon the shape of the pipe or duct inlet.