Emission of firedamp

• Pages: 18-20

3. Emission of firedamp

3.1.

Rapidly advancing faces '

3.1.1.

(1) Although the effect of increasing firedamp emis-

sions may be moderated by increasing the quantity of air passing

along the face, the limitations of this practice, mainly in regard to

the ventilation velocity that can be accepted, should not be over-

looked.

(2) Unless and until other means can be used to prevent an

excessive increase of the firedamp concentration in the ventilating

air, it may be necessary to stabilise the firedamp emission rate by

avoiding any further increase in the rate of mining the coal and

in its degradation.

3.2. Strata control

3.2.1.

(1) Good strata control should be ensured.2

(2) Close liaison should be maintained between ventilation and

strata control engineers.

(3) The mine manager should be able to call for the advice of a

specialist strata control engineer whenever required.

1 It should be noted that although the effect of firedamp drainage is to

remove much of the gas from the surrounding strata, thereby keeping the

explosive fringe well clear of the waste edge, it will have little influence on the

emission of firedamp from the working face. On a rapidly advancing face in

a gassy seam a marked increase in firedamp emission can take place towards

the end of a working

week.

Similarly, the emission can become higher towards

the end of a continuous series of

strips.

In addition, the quantity of firedamp

released in any given period is related to the rate of face advance and to the

degree of degradation caused in getting the coal.

2 Strata control is an important factor in reducing the explosion risk.

Excessive and abnormal roof movements often lead to falls of ground sufficient

to displace the firedamp and to upset the normal flow of ventilation, thereby

reducing the usual margin of safety.

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