|Carbon Monoxide (CO). by Mr. W. Clifford
Carbon monoxide is found after an explosion and it is often given off from fires, especially gob fires. It is the result of incomplete combustion, due to the fact that there is not enough oxygen in the atmosphere to combine thoroughly with the carbon of the exploding or burning material. If sufficient oxygen is present, the explosion or combustion is complete, and carbon dioxide, a comparatively harmless gas is the result. If however, there is insufficient oxygen, the carbon can only combine with an equal amount of oxygen instead of double the amount, and carbon monoxide is formed. Carbon monoxide is composed by weight of 56.59 per cent of oxygen, and 43.31 per cent of carbon. Its specific gravity is 0.975, air being 1 so that is very slightly lighter than air.
Chemical Formula: CO
Specific Gravity: 0.967
Needs 6% 02 to ignite
Ignition temp 1100’F
Explosive Range: 12.5 – 74%
TLV: 50 ppm
Source: incomplete combustion, diesels, gasoline engines
Characteristics: no colour, odour or taste
Effect on the body: 300 times more attracted to haemoglobin than oxygen
It is a colourless odourless gas, and will burn with a faint blue flame. If present in sufficient quantities, 12.5% to 74%, it explodes with great violence on contact with flame. A safety lamp is of no use whatever for testing for this gas, as although a cap similar to a firedamp cap may be detected, the percentage of gas which would produce a cap would have killed the observer long before he had drawn the wick of his lamp down. It is essential that the very slightest trace of carbon monoxide should be discovered and guarded against, so that the only safe way is to employ a small bird or animal such as a canary or mouse using a breathing apparatus at the same time.
To understand the reason for it, it is necessary to explain to some extent the action of the gas on the system. The blood contains certain cells corpuscles, whose function is to convey oxygen, taken from the air in the lungs, to every part of the body. These cells have a great affinity for oxygen, but unfortunately they have a far greater affinity for carbon monoxide, over 250 times. In fact if air containing the least percentage of carbon monoxide is breathed, the blood will pick up every particle of it, leaving the oxygen to be exhaled. Every blood cell, which comes into contact with carbon monoxide, is actually poisoned, and the poison is thus carried round to every part of the system. The system then suffers in two ways, first, by actual poisoning, and second by oxygen starvation, the body being deprived of the oxygen, which has been displaced by the carbon monoxide. In time, which varies according to the percentage of gas inhaled and to a certain extent to the amount of work being done, the body is rendered helpless, and death follows very quickly.