From ventilation Book

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.