Introduction to Health and Safety at Work

particles. It is normally replaced after 8/10 hours of 
use. It offers protection against some vapours and 
gases
➤
a 
half mask respirator
– made of rubber or plastic 
and covers the nose and mouth. Air is drawn through 
a replaceable fi lter cartridge. These can be used for 
vapours, gases or dusts but it is very important that 
the correct fi lter is used (a dust fi lter will not fi lter 
vapours)
➤
a 
full face mask respirator
– similar to the half 
mask type but covers the eyes with a visor
➤
a 
powered respirator
– a battery-operated fan 
delivers air through a fi lter to the face mask, hood, 
helmet or visor.
Figure 14.11
Personal protective equipment at work.

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Introduction to Health and Safety at Work
240
Breathing apparatus is used in one of three forms:
➤
self-contained breathing apparatus
– where air 
is supplied from compressed air in a cylinder and 
forms a completely sealed system;
➤
fresh air hose apparatus
– fresh air is delivered 
through a hose to a sealed face mask from an uncon-
taminated source. The air may be delivered by the 
wearer, by natural breathing or mechanically by a fan;
➤
compressed air line apparatus
– air is delivered 
through a hose from a compressed air line. This can 
be either continuous fl ow or on demand. The air 
must be properly fi ltered to remove oil, excess water 
and other contaminants and the air pressure must 
be reduced. Special compressors are normally used.
The selection of appropriate respiratory protective equip-
ment and correct fi lters for particular hazardous sub-
stances is best done by a competent specialist person.
There are several important technical standards 
which must be considered during the selection process. 
Respiratory protective equipment must either be CE 
marked or HSE approved (HSE approval ceased on 30 
June 1995 but such approved equipment may still be 
used). Other standards include the minimum protection 
required (MPR) and the assigned protection factor (APF). 
The CE mark does not indicate that the equipment is 
suitable for a particular hazard. The following information 
will be needed before a selection can be made:
➤
details of the hazardous substance in particular 
whether it is a gas, vapour or dust or a combination 
of all three
➤
presence of a beard or other facial hair which could 
prevent a good leak-free fi t (a simple test to see 
whether the fi t is tight or not is to close off the air 
supply, breathe in and hold the breath. The respirator 
Figure 14.12
Types of respiratory protective equipment. (a) Filtering half mask; (b) half mask reusable with fi lters; (c) com-
pressed air the breathing apparatus with full face mask fi tted with demand valve.

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