ENMET SPECTRUM-RAL-DC - Manual (Page 17)

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Appendix A
The Characteristics and Effects of Carbon Monoxide
Carbon monoxide is a colorless odorless toxic gas generated by incomplete combustion of a hydrocarbon fuel
in air. It may be present where internal combustion engines, furnaces, boilers, and other combustion devices
are present. It is toxic when inhaled because of its great affinity to hemoglobin, the oxygen carriers in the red
cells of the blood. CO replaces the oxygen normally carried by the hemoglobin, and thus inhibits the delivery
of oxygen throughout the body; the victim suffers from oxygen deficiency, and may die from asphyxiation.
The symptoms and degree of danger resulting from exposure to CO depend upon the concentration of the gas
and the length of exposure; this is shown in Figure 4. The ENMET SPECTRUM-DC-RAL carbon monoxide
monitor is employed to warn the user of the presence of CO, and to facilitate the assessment of the degree of
danger that he or she is exposed to.
Based upon knowledge of the effects of CO, the Occupational Safety and Health Authority (OSHA) has set
limits on exposure to CO in the workplace. For ambient air conditions, these are 35 ppm (parts CO per
million parts air) as an time weighted average for an eight hour day, and a maximum exposure of 200 ppm.
For compressed air line applications, 10 ppm is the maximum acceptable limit. The SPECTRUM-DC-RAL
monitor is shipped with the adjustable alarm set at 10 ppm; this alarm cannot be adjusted above 50 ppm.
The curves below are for percent carboxalhemoglobin with 50% being the top curve, 5% the bottom.
%COHb is a measure of the amount of hemoglobin occupied by CO rather than oxygen. CO effects upon
children, adults engaging in physical activity, and smokers, are more pronounced.
Figure 4 % COHb vs Time