This document classifies and describes different types of mechanical ventilation devices used in mines. It discusses fans, compressors, injectors, and the different types of fans including centrifugal fans, steel plate fans, multi-blade fans, axial flow fans, and mixed flow fans. Compressors are described as being similar to high pressure fans. Injectors are explained as using compressed air to induce airflow into ducts or pipes and are simpler and cheaper than fans but less efficient.

1. Classification of Mechanical
Ventilation Devices
Sadam Bin Samee
8th semester Mining Engineering
UET Peshawar.

2. Mechanical ventilation devices
• All powered machines that induce airflow in mine ducts and openings
• Fans are the most important and most common of these
• Compressors and injectors are also used for auxiliary purposes
• The following photo taken from the book shows this classification:

4. Fans:
• It’s a kind of pump creating P difference in a duct or airway and thus
ensure airflow
• It receives air at some intake pressure and discharges with high
Pressure
• Convert mechanical energy to fluid to overcome head losses
• Prime mover may be Electric motor, int. combustion engine or
compressed air turbine.
• in centrifugal Fan air is drawn into a rotating impeller and discharge
radially into a scroll casing.

5. Continued….
• In steel plate fan the impeller mount few large, flat blades.
• In Multi-blades fan has many small curve blades( may be of varying
curvature)
• Axial flow fan consist of an impeller in a cylindrical housing and air-
foil-shaped blades.
• Causes the air flow in axial direction
• The difference in tube axial and vane axial is provision of stationary
guide vanes to recover rotating imparting energy from blades.
• Mixed flow fan has the appearance like axial flow fan and having a
casing flaring in direction of air while blades resembles cross between
both

6. Compressor:
• They may of thought of high pressure fan b/c they perform like air
pumps in ventilation system.
• The axial and centrifugal compressors resembles fans of the
corresponding classes.
• They handle smaller volume with much higher Pressure than fans
• Positive blower is having 2 impeller and a mesh in such a way to send
constant volume of air at varying P.
• Having ventilations tubes and used for long tunnels
• Resistance increase with length

7. Injectors:
• They direct a jet of compressed air into a short pipe or ventilations
duct end and induces air flow.
• The name of injector depends on pipe and duct inlet
• They are less efficient and costly to operate comparatively to fans.
• However they are simple to install and no maintenance cost and low
first cost.
• They are good where compressed air is available while electricity is
not.
• They can operate in condition where fan wouldn’t.
• They are used without tubes are small tube for ventilation at dead-
end working areas

9. Thanks