The principles and practice of colliery ventilation: Being a Treatise on the Laws Governing the ... by Alan Bagot

Author:Alan Bagot
Language: eng
Format: epub
Publisher: [s.n.]
Published: 1879-03-25T05:00:00+00:00

Regnault, let us suppose a volume of air to be represented by 1 at a temperature of 32° F the volume is increased to r367()6 ; that of hydrogen to 1'36613, and that of carbonic acid to 1'37099. The laws that govern this important feature of gases, viz., their expansion, under an increase of temperature may be deduced from the following.

Absolute Temperature.

It has been assumed that since air expands as its temperature increases, so would it on the other hand diminish its volume if the temperature fell; thus if at 32° jf, air as a volume of 1, it is assumed that on arriving at a temperature of 493°.2 below freezing point, 46l°.2 F below Zero, the air would be so attenuated as to be in a state of collapse, and would possess no elasticity. This point is called Absolute Zero, and then the temperature of any body measured from absolute Zero, is called the absolute temperature of that body.

Thus if a given quantity of air at 0° FhQ raised to + 461°/^, it is (if under a constant pressure), expended to twice its original volume ; if heated to 922° Fy its volume will be trebled.

Therefore the laws to be borne in mind are—

i. The pressure of air or any gas varies inversely as the volume when the temperature is constant.

ii. The pressure varies directly as the absolute temperature, when the volume is constant.

iii. The volume varies as the absolute temperature, when the pressure is constant.

iv. The product of the pressure and volume is proportional to the absolute temperature.

The Absolute Zero of the three Thermometer scales are—

Fahrenhit 461°.2

Reamur 219°.2

Centigrade 274°. 00

but to avoid excessive labour in calculation, it will suffice to drop the decimal reading. Gas compounded of carbon and hydrogen occasionally throws out oily products, which will interfere with the action of these laws.

It will be seen, therefore, that violent changes of temperature in ventilation are to be avoided in working fiery and brassy . mines, or gas will be liberated that otherwise would have re-mamed in the seam.

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CHAPTER VII.

General Observations with regard to Ventilation in

Practice.

Ventilation in theory will be found a compaxatively easy matter; in practice, however, falls of roof and the carelessness of the miners will be found a source of endless annoyance and anxiety. A miner is bound by laws (Sec. 55 Coal Mines Regulation Act) to report instantly to the fireman should he discover anything wrong with the ventilating current, or the state of the roof or mine generally, such as leads him to suspect danger to himself or his fellow workmen. This is not always done, as the Act requires, instantlyy and the duty of every manager is plain where this is the case; the Act having been broken, the miner should be punished under the Act. Such very strong assertions are made concerning the management of collieries by men, whose very assertions shew their ignorance of the subject, and since such assertions, being those of uneducated men, are always directed more or

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