(to determine flow rate); flow rate control valve; and suction pump. The suction pumps
will require some sort of power supply; some particulate separators also require an
additional source of electrical power. A sampling train for gas or vapor would be similar,
except that some type of absorption or adsorption device would replace the particulate
separator. Refer again to Figure 2-5 for an example of a sampling train, in this instance,
assembled to sample for respirable dust).
e. Calibration. The accurate analysis of a contaminant's concentration in the
work environment is possible only if the volume of the air sample can be accurately
determined and the efficiency of the collection device maintained at its maximum. For
these reasons, frequent calibration of all equipment is essential. While it is important for
you to be aware of this requirement, you will probably not be required to be able to
actually calibrate the equipment. A detailed discussion of calibration techniques is
beyond the scope of this subcourse.
Section IV. RESPIRATORY PROTECTIVE DEVICES
One of the major routes of entry for toxic substances is through inhalation.
Almost every industry has some form of respiratory hazard associated with it. Industrial
type operations carried out on Army installations have hazards too. In the field of
industrial hygiene, our primary concern is to protect the worker from exposure to
hazardous situations in the work environment. One method of eliminating an inhalation
exposure is to place a barrier between the worker's respiratory tract and the hazardous
environment. You may recall that in lesson l we referred to Pliney the Elder, who, in 60
AD, reported that a goat's bladder placed over the face could protect workers from the
hazard of working with lead (the bladder is a barrier between the worker's respiratory
tract and the hazardous environment). Respirator design has come a long way since
that time; however, the improper use of a respirator or the selection of the wrong one
can leave a worker with a false sense of security, and possibly less protection than he
might get with a goat's bladder. As a preventive medicine specialist, you may be called
upon to evaluate the use of respirators and to train employees in their proper selection,
use, and maintenance.