used in underground coal mines

1. By
M.SATHWIK

3. • It works on the principle of WIRE GAUZE
• J.K.DEY& sons introduced flame safety lamps with
trade name VELOX.
• GL-50 is permitted by DGMS for gas testing in degree-
1&2 mines gassy coal mines.
• Gl-60 is permitted for all degree gassy mines

4. BONNET:-
It protects
the wire
gauge from
damage due
to external
hit.
It also
guards the
flame
againist high
air velocity.

5. OUTER
GAUGE:-
•The function of
outer gauze is to
prevent the
passage of flame
from outer gauze
.
•While hot
combustion gases
passes heat is
absorbed by
gauzes which
then dissipiate by
way of radiation.

6. INNER
GAUGE:-
•The function of
gauzes is to
prevent the
passage of flame
from interior to
exterior of lamp.
•The gauzes are
made of
COPPER Wire of
28 mesh.

7. FUEL
VESSEL:-
Kerosene oil and
ESSO-
SOLVENT
NO.1425,SOLVE
NT are used in
lamps.
More volatile
fuels like Mineral
colza, paraffin &
naptha are used.

8. • A Set of fiver pillars to protect the Glass from external
hit.
• The bonnet rests on pillars over the oil vessel.
• Angle between two pillars is 72 degrees

9.  Two asbestos rings are fixed at top and bottom of glass
are to prevent the gases to come outside.
 Magnetic lock:-
 Safety lamp should be kept securely locked.
 Magnetic lock is used to locking or unlocking the safety
lamp .
 The magnetic lock prevents the lamp from opening
underground for any purpose.

10. It should be tough quality glass and of sufficient thickness
so as to withstand the shock pressure should an explosion
occurs inside the lamp.
Glass cylinder should be 4-5mm thick.

11.  WICK adjuster is to adjust lower or higher the flame.
The wick passes through the wick holder.
• Wick may be either flat or round one ,flat wick is
generally wider than round one.
• Wider the wick, longer is the cap.

12.  Sharp detection of methane gas .
 Detect the shortage of oxygen gas.
 Detect the presence of carbondioxide gas.
 Magnetically locked equipment .
 Top feed device for testing methane gas close to roof.
 Safety lamp is used for detecting or estimating of firedamp
by ACCUMULATION TEST& PERCENTAGE TEST.
 Weight of safety lamp is 1.7 kg.
 The whole lamp is made of such metals as to make it robust
for underground use .
 All the metallic components also help in dissipiating heat
of lamp.

13.  Flame safety lamp gives a good warning againist
oxygen deficiency in air.
 For each 1% oxygen deficiency from the normal
concentration the light output decreases by (30%).
 Below 17%-17.5% Oxygen ,the lamp will be
extinguished.
 In Accumulation test spiring (or) jumping of flame
gives the positive response indicating an accumulation
of gas not less than 3%.
 If accumulation test shows positive response then it is
not wise to go for more precise PERCENTAGE test.

14.  If safety lamp gives negative response the percentage
test is carried out because it may contain gas not less
than 3% in air.
 Percentage test is carried out to estimate concentration
more (or) less accurately.
 Below 1.5% methane the gas can be hardly identified.
 The percentage test is carried out with a range of
1.5%to4% methane with an accuracy of 0.25%.
 Above 4.0% methane tip of flame is generally not
visible as it becomes longer than glass height.

15. • During percentage test the gas cap is first noticeable at a concentration of 1.5%.
• At 1.5% gas cap is not fully developed but it appears as a truncated cone with
concave(or) rounded tip.
• The height of cap is 4mm.
• At 2.0% methane the cap is fully formed but with a rounded tip.
• The height is of 6mm.
• At 2.5% methane ,a first triangular cap with sharp apex is first formed at a height of
8mm.
• At 3.0% methane , a triangular cap with sharp apex is formed with a height of 12mm.
• At 3.5% methane , at triangular cap is formed with a height of 18mm.
• At 4.0% methane ,a triangular cap is formed with a height of 28mm but it is generally not
visible because it is high than glass height.
• THE END.