Annual Report,2009 - Directorate General of Mines Safety

DGMS Annual Report, 2009
Though IS: 9968 (Part – I) does not speak about metallic screening for cables
at voltages above low voltages, however, to afford protection against
mechanical injury, it imperative that flexible cables for use in oil mines must
have metallic screening also.
8.0 Hence it becomes mandatory that
(a) The flexible cables used to connect 3 phase electrical equipments shall
be EPR (Ethylene Propylene Rubber [IE-2]) insulated and HOFR (heat
resisting, oil resisting & flame retardant) Elastomeric CSP (Chlorosulphonated
Polyethylene) sheathed, either individually or collectively
copper screened, 4 core copper conductor cables with fourth core
having 50% conductivity of the largest conductor and the combined
screen having 50% conductivity of the largest conductor.
(b) The flexible cables used to connect light fittings shall be EPR
insulated, and HOFR elastomeric, CSP sheathed unscreened 3 core
copper conductor cables.
(c) The flexible cables used with alternators & DC motors shall be single
core EVA (Ethyl Vinyl Acetate Rubber) insulated and sheathed, copper
(d)
conductor cables, and
The flexible cables used for control connections shall be EPR
insulated, and HOFR elastomeric, CSP sheathed, copper screened
flexible copper conductor cables having cores upto 20 and.
Shall generally conform to IS : 9968 (Part – I)
9.0 Termination of flexible cables with electrical equipments installed in
hazardous area shall be through appropriate size of double compression glands and
with electrical equipments installed in non-hazardous areas shall be through a readily
detachable plug and socket assembly.
No. DGMS (Tech)/Circular No./ 10
Dhanbad, Dated – 13/July/2009
To,
Owner/Agent/Manager of All Mines & The Manufactures.
Sub:- Standards Composition and properties required for Resin Capsules to be
used as grouting material for Roof Bolting in Mines.
1.0 BACKGROUND
As soon as the roof in coal seam is exposed, the immediate roof starts dilating and
getting detached from the overlying layers of roof strata causing it to fail if not
supported properly. Roof Bolts are therefore being used as common support in
underground mines all over the world along with the cement or resin grout to
reinforce the strata and provide adequate support in the excavation.
It is highly desired that the roof bolts once installed should immediately start taking
load of the roof strata and prevent dilation so as to eliminate changes of roof fall.
Resin Grout is a very effective material which sets very fast and prevents roof dilation.
Although rapid set cement capsules are also being used as grout in roof bolting, but its
setting time and time to provide reinforcement in the strata is too long to arrest the
roof dilation. During impending loading on the roof bolts due to stressing of the strata
172