1 Safety Equipment (Operator )
( A ) Always wear a Hard Hat when Drilling.
It is a very real possibility that a Drill string coupling can break and become airborne,there is also the risk of an airline blowing out and hose fittings can become airborne as well.
( B ) Always wear eye protection & Ear Protection
Never walk on to Drill Site without Safety Glasses. Drill cuttings being ejected from the Drill Hole with Compressed air can be very hazardous to your eyes. Drilling Rigs can operate at a very high Decibel Rate up to 120db +, always wear proper Ear protection, earmuffs or earplugs.
( C ) Always wear Safety Shoes (Steel capped boots ) and use Heavy Gloves.
Drilling consumables are not only heavy; they also get very hot during Drilling.
Safety footwear should always be worn around Heavy Machinery because of the possibility of the machine shifting position and moving onto the operator’s feet.
(D) Always wear suitable work clothing.
Loose flowing clothing can get caught up in the Drilling Mechanical workings.
Such as the feed chain and sprockets, drill string and Tracks while Tramming
- Safety Warnings on machinery
(A) Read all Operational Safety Instructions associated with the Drilling Equipment!
If Machinery manuals are available read them to familiarize yourself with the drill and it’s capabilities.
DO NOT try to get more production out of the drilling machine than it is designed for.
( B ) Keep all Safety Warning Signs wiped clean on the machinery , other Operators may not be familiar with this particular machine.
PRIOR TO MACHINERY STARTUP
1: Check all Fluid Levels on Compressor and Drill
(1 A) Compressor
Engine Oil: Use only approved engine oil for top up, refer to manual for description.
Ensure the oil filler cap has not been tampered with, if contaminates have been placed into the oil filler hole severe damage can be done to the engine.
Radiator Coolant: Use only approved coolant and top up with additive if required.
Compressor Oil: Usually a site gauge is present on the receiver tank.
See Compressor manual if unsure. Use only approved Compressor Oil.
Receiver Tank: If fitted Drain off any water from the receiver tank, open tap slightly and let any water drain off, close tap when Oil appears.
(1 B) Air Track
Rock Oil: A very heavy oil specially designed to lubricate the Drifter and other air driven motors on the same line as the Rock Oil tank.
NOTE!
Use only the specified by the manufacturer as using other oils can damage and weaken air hoses that carry high-pressure air!
Hydraulic Oil: This oil is much lighter grade than that of Rock Oil.
An Air Motor drives a Hydraulic pump to operate all of the Rams that control the lift, swing and tilt on the Drill Guide and other associated controls.
Cyclone Lubricant (Dust Collector): Usually a small Glass bottle located on or adjacent to the Dust Collector, Because it is an air motor a Light Rock Oil is recommended.
Air Water Traps: Drain water from water traps to ensure the smooth operation of the Dust Collector, Pulsating Mechanisms in the Dust Collector require clean air and free of moisture.
2: Pre Startup Procedure
(2 A) Ensure all air hoses are secure and all safety chains are in place.
Ensure all Air Track controls are in a neutral position or in such a way that the Drill can not move EG: Especially the feed controls that control the drill string,
And tramming controls that control the forward and reverse movement of the Drill Rig.
NOTE!
If in doubt close the main air tap at the back of the Drill rig.
(2 B) Ensure all Brakes are applied to the Compressor and chock the wheels before moving the Drill away from the Compressor.
(2 C) Grease all Nipples associated with moving parts that are constantly working throughout the day:
EG: Top and Bottom Feed chain sprockets (Twice daily),
Drill rod centralizer (Twice Daily) or as required, if drill cuttings are very prevalent around the centralizer then more frequent greasing may be required.
Grease all Track Idlers and Sprockets if a lot of tramming is to be done.
Check Track Adjusters for tension and adjust if necessary.
All ram joints should be greased at least once a week, depending on the amount of work done.
(2 D) Drill Collar Water Tank.
Close Main Air Tap behind the Air Track.
Ensure no Air is contained in the tank by opening the relief valve or tap and releasing the pressure,
DO NOT!
Place any part of your body in line with the air venting out of the tank.
Compressed air is extremely dangerous and can cause sever damage to the eyes
If particles or drill foam are ejected with the compressed air.
The recommended practice is to insert Drill Foam (Commercial Detergent) with the water; this assists with the collaring of the drill hole and the cleaning out of difficult drill holes. Generally 1 to 2 liter’s of Drill Foam to each full tank of Water.
Ensure Taps and or filler bungs (caps) are tightened securely.
Failure to do this can cause the bungs (caps) to be ejected in to the air as compressed air fills the tank.
- : Inspection of the site to be Drilled
Even if the Drill site has already been marked out for Drilling, Inspect the Bench and Face from a safe distance.
Look for Jointing Planes in the bench where it is possible for the ground to slip when machinery is operating on it, also check the face for any overhangs where holes may have been marked out on it, In general check for anything that could be detrimental to the safe operation of machinery and operator.
If in doubt DO NOT move the machinery onto the Drill Site, and contact the relevant person in charge.
NOTE!
If there is insistence in placing the Drilling and Operator in a detrimental position it may be necessary to contact your Employer, Union and Health and Safety Dept.
4: Procedural Information
Once the Drill Site has been established as appearing safe,
Proceed to mark out Drill Pattern if not already marked out.
Use Drill Pattern Parameters set out to suit the type of material to be blasted.
Drilling Properties
Burden: Distance from the Crest (Top) of Face and Subsequent Rows Behind.
Spacing Distance between Holes Parallel to the face.
Hole Depth: Total Depth of Hole including Subdrill.
Subdrill: The part of Drill hole below the floor that is to be blasted
Generally about 1 mtr, this is to keep a level floor after blasting.
Angle of Blasthole: To be determined by the Angle of the face to be blasted, type of Explosives that are going to be used and the amount of throw required.
Bench: The working area where Drilling & Blasting is to performed.
Face: The Vertical area in front of the Bench that where the Drill Holes will be directed.
Crest: The point where the Bench meets the Face.
Toe: This is the most important part of the Face (Where the floor of the Pit meets the face) Failure to have the correct Burden in this area can result in either Flyrock (To Less a Burden) or being unable to excavate the blast properly (To Greater a Burden) This will also transfer a higher Toe area to subsequent Blasts behind.
Floor: Working Area below the Bench where the Blast is to Excavated.
ALWAYS ENSURE OPTIMUM BURDEN IS ACHIEVED!
5: Prepare Drill Site for Drilling.
Setup Drill stand (If Drill is not fitted with Drill Steel Rack) adjacent to the first hole to be Drilled, but far enough away so that Dirt & Drill cuttings do not stick to the Greased Threads of the Drill Steel.
Keep on hand extra Drill Steel, Couplings, Shanks & Sharp Drill Bits.
Drilling Grease (MolyBond GOG) or equivalent should be used and kept in a covered container.
Check all Drilling Consumables for wear or damage before Drilling.
Ensure the Main Air Hose (Bull Hose) has sufficient length to reach from the compressor to the holes to be Drilled, DO NOT try and stretch the bull hose with the machine to reach the holes as this can result in the hose separating from the fittings.
Use the Air Track to move the Compressor if it is safe to do so, otherwise obtain another length of bull hose to suit, ensuring that all Safety chains are fitted.
Bearing in mind that the more Bull Hose from the Compressor to the Air Track gives less operational Air for the Drifter and Drill.
6: Starting Compressor and Setting Up Drill Rig.
Start up Compressor after all Initial checks have been done.
Let Compressor Idle until the operating temperature has been reached, usually
Five to Ten Minutes.
Once the Compressor has reached operating Temperature, Open any valves if fitted to let the Compressor Draw Air. ( Gardener Denver Compressors have a Butterfly Valve above the Compressor Screws ).
Slowly open the Main Air Tap from the Compressor.
NOTE!
Watch the Drilling Equipment in case of any Movement (The Drilling Controls should have been checked prior to Startup).
Ensure that the Compressor is no more that 15 degrees in either way as they are designed to operate on level terrain.
Relocate if necessary to a Level location.
Uncouple the Air Track from the Compressor (Usually a Pin Hitch between the Drill & Compressor).
Lay out Bull Hose on the ground in such a manner that it can not damaged by being run over with the Drill or other machinery or get tangled with itself.
Position the Drifter AT THE BOTTOM OF THE OF THE DRILL GUIDE before moving the Drill Rig, remove any the Drill Steel if necessary.
NOTE!
It has been noted that on several occasions operators have moved the Drill with the Drifter high up on the Drill Guide, Subsequently with all the weight on top of the Drill Guide, Pins have sheared on the pivot point (Goose Neck) of the Drill Rig.
Several Operators have been seriously Injured and Killed operating in this manner.
Tram (Walk) the Drill Rig to the first hole to be drilled, generally the further most point on the pattern where the cuttings from the Dust Collector will not fall on to pre marked out holes (many a hole has been missed drilling because of the marker being buried).
DO NOT try and stretch the Bull Hose beyond it limit! Shift the Compressor if necessary.
7: Aligning the Drill Rig and Preparing to Drill
Position the Mast (Drill Guide) over the Drill Hole Marker, Apply Brakes to the Drill Rig if they are not automatic.
Use plenty of downward pressure on the Drill Guide to ensure the machine will stay in place, generally it will lift the front of the Track Frame of the ground.
Raise the Drifter to the top of the Drill Guide, open Centralizers ensuring that your hand and clothing are clear and will not get caught up in the Feed Chain if still moving. DO NOT place any part of your body underneath the Drifter.
NOTE!
If the Feed Chain breaks the Drifter can become a Guillotine and can sever any body parts below it.
With the Centralizer open pick up the first Drill Steel to be used it should have a Sharp Bit on one end and a Coupling on the other end (The Steel Treads should be liberally greased with drilling grease),
Place the Bit End of the Drill Steel at the base of the Drill Guide, between the centralizer; raise the Drill steel so that the coupling is directly below the Drifter ShankPiece. (It takes a bit of practice to hold it steady)
Move the Rotation lever in to forward position at about one ¼ quarter speed.
Slowly pull on the Feed Lever to lower the Drifter until the Shank piece connects with the coupling, it will screw into the coupling, once the connection has been made remove your hands from the Drill Steel and Stop Rotation and STOP pulling on the Feed Lever. (Too much pressure on the feed lever will result in the Drill Guide Kicking out) at this stage it is best put into a neutral position or have it hold the Drill Steel just above the Ground.
Close Centralizers around Drill steel.
8: Setting Angle of Drill Guide and Squaring up Holes
To set the desired or designed angle of Drill hole use a Clinometer (Angle Setter) or similar. Set the desired angle on the Clinometer and place on the drill steel use the guide slide control to adjust the angle of the drill steel to suit the angle on the Clinometer, ensure there is still enough weight on the Drill Guide so that the Drill does not move, Use the mast lift control to put more weight on the Drill Guide.
It is very important when drilling to make sure that each hole lines up with the next hole in front and square to the Face to be Blasted. This can be achieved by using a Plumb Bob.
Position yourself directly in front of the Drill Rig and square to the face, if room permits use the Drill pattern markers as a guide, from the Drill Rig go forward 2 holes and holding the Plumb Bob directly over the second marker site through to the first marker and on to the Drill Steel, use the Guide Swing to adjust if necessary.
If a front hole is to be drilled follow this procedure from behind the Drill Rig, as it can be very dangerous to stand near the Crest of a Face.
TIP!
A second person can be very useful when Plumbing up a Drill String.
9: Starting to Drill (Collaring)
To ensure a clean hole is drilled collaring the first metre of the Drillhole is very important.
Lower the Drill Steel until the Bit is just touching the Ground whilst having the rotation set at around ¼ to ½ speed, turn on the the water tap that contains the Drill Foam Mixture, Open up the Hammer Controls to about ¼ to ½ power and open the flushing air tap only slightly, water should visibly be seen coming out of the freshly started hole, if Pull up immediately as it possible that the bit is blocked.
After about ½ a metre or so turn of the Water, Hammer and Flushing Air, Pull up Drill Steel until the Drill Bit is just visible inspect the top of the hole to see if it not broken around the surface.
NOTE!
If the ground and hole does not appear solid shovel some drill cuttings into the freshly started hole, (A mixture of Cement and Drill Cuttings can be used in badly broken ground) NEVER USE YOUR HANDS TO PUSH CUTTINGS INTO THE HOLE AS THE DRIFTER COULD COME DOWN TRAPPING YOUR HANDS.
Once the top of the hole appears solid proceed to start drilling, lower the drill steel down the collared hole, open the rotation to ½ speed, open the Hammer controls to about ¾ power and open Flushing air to about ½ way and increase feed pressure on the Bit.
When Dry Cuttings and Dust appear out of the drill hole turn on the Dust Collector to start extracting Dust.
With the moisture still on the wall of the drill hole dry dust coming up the hole will pack solid the wall of the hole.
Once this process has been completed all of the controls can be opened up for optimum drilling.
10: Adjusting Feed Pressure
Inadequate Feed Pressure
In order to adjust feed pressure properly, listening to the drill rig is the best method.
If the Drill String sound like it is Chattering or Rattling then more feed pressure is required. Inadequate feed pressure will give poor energy transfer from the Drifter Piston to the Drill Bit. This energy is lost as Heat into the Drill String and can result in the Lockups of Couplings, also Buttons or carbide Chisels can break loose from the Drill Bit.
Excessive Feed Pressure
Screeching or the Drill Rig sounds like it is struggling to drill the Hole is a sign of Excessive Feed Pressure.
Excessive Feed Pressure can result in excessive bending stress on the Shank, Couplings and Drill steel. This will cause Failure and Breakage’s of the consumables.
Blockages of the Bit can also be a result of overfeeding and ultimately the Drill string may become stuck (Bogged).
TIP!
When the Drilling Rig Sounds Right it probably running Right!
11: Cleaning the Drill Hole
Poor hole cleaning is the main reason for Stuck (Bogged) Drill Strings.
Before adding another Drill Steel, Turn of Hammer, Pull back on the feed lever until the bit clears the bottom of the hole by about 100mm, turn the Flushing air on Full
And then cycle the Drill String up and down 3 or 4 times without touching the bottom of the hole. This process will usually keep the number of drill cuttings left in the hole to a minimum.
12: Adding to the Drill String
Most Drilling and Blasting production operations require more than one drill pass
Upon completing the first section of drill steel clean out the hole described in the previous procedure, restart the drill as if to continue drilling then move the rotation lever into the neutral position until you can here the Coupling Rattle, close of all hammer, air and feed controls. (Rotation should still be in neutral position (Not Reverse)).
Raise the drill string till the bottom coupling is above the centralizer, close centralizer and lower the coupling onto it.
NOTE!
If the coupling thread is not free DO NOT HAMMER ON TO THE CENTRALIZER, go back down the hole and rattle the coupling again.
Unscrewing the coupling can be done by floating the drifter, Raise the drifter until there is no weight on the drill string and buy pushing the rotation lever slowly in reverse and raising the drifter at the same time the coupling will unscrew, it may be nesassary to place you foot against the side of the coupling to stop it unscrewing from the drill steel, (Ensure Safety Boots are being used) if the coupling does unscrew DO NOT Pick it up with bare hands, they get Extremely hot.
When the Drifter is separated from the drill string you should notice a film of Oil coming down from the Chuck in the Drifter and coating the Shank, if this is not the case adjust the Oil flow regulator on the Rock Oil tank as damage can occur to the drifter if there is an insufficient oil flow through the Hammer.
Move the Drifter to the top of the drill guide and hold in position with the control,
Pick up the next length of drill steel ensuring that both ends have been greased with suitable rock grease ( Molybond GOG or equivalent).
Place the threaded end of the drill steel onto the coupling and swing the Drill Steel up into a position so that the coupling on the new Drill steel is directly below the shank, slowly lower the drifter with about ¼ rotation to screw into the top coupling once the connection has been made remove your hand from the drill rod, stop the rotation and raise the drill string till the bottom coupling clears the centralizers,
Open the centralizes and commence drilling as previously described
13: Removing the Drill String (Drawing)
Removing (Drawing) the Drill string can be achieved by using the following procedure.
Upon completion of the drill hole clean out the hole as described earlier.
Break out coupling by rattling the hammer at the bottom of the hole with the rotation in neutral (Not Reverse, as this can unscrew the drill steel from the couplings down the hole), with practice you will be able to tell by the ringing sound that Broken out couplings make.
Leaving the rotation in neutral turn off the hammer but leave the Flushing air on draw the drill string up the Drill Guide, when the Drifter is at the top of the Drill Guide turn off the flushing air and close the centralizers ,then lower the bottom coupling onto the centralizers (Ensuring the whole time that no part of your body is in line with the Drifter).
As with adding drill steel float the drifter so that there is no weight on the drill string and top coupling, Slowly rotate in reverse and raise the drifter at the same time, this will unscrew the shank from the coupling.
NOTE!
Watch the Drill String the whole time as the top coupling can unscrew from the drill steel and become airborne, also if the bottom coupling unscrews the drill string can fall back down to the bottom of the hole.
This can be a real problem if several drill steels have already been drawn.
Once the shank has unscrewed from the coupling raise the drifter to the top of the drill guide and hold in position with the controls.
Using Heavy Gloves unscrew the drill steel by hand in an anti clockwise motion.
You may be required to place your foot against the bottom coupling to stop it unscrewing and losing the drill steel beneath it.
Once the Drill Steel has been unscrewed place it back on the drill stand in the same location that it was removed from (Unless you are Rotating your drill String).
Lower the Drifter down onto the next coupling using around ¼ speed rotation pick up the next Drill Steel and use the procedure above for all subsequent pickups of the drill string.
On the last drill steel with the bit attached slowly draw upwards and turn off the flushing air about ½ metre from the surface close the centralizer Bolt and draw the Bit up firmly under the centralizer to hold in position ready for the next hole.
Inspect the hole to make sure it is clean and measure it to ensure it is the correct depth. (At no time place your hands in the hole without moving the Drill Guide Away).
Carefully raise the Drill Guide and move it away from the hole, making sure no debris has fallen down the hole (Remeasure the hole if necessary).
Plug the hole with a cap or plug (Using an old ANFO bag formed in the shape of a cone and filled with drill cuttings is a common practice).
14: Moving to the next hole to be Drilled
Raise the Drill Guide clear of the ground and markers and ensure that the drill steel is still firmly held under the centralizer,
Raising the drill guide 150 to 300 mm is sufficient.
NOTE!
In difficult terrain it may be required to lower the Drill Guide to maintain a stable center of gravity.
Always be aware that the drifter in the position at the top of the Drill Guide puts a strain on the pivot point (GooseNeck) and under no circumstances should the drill guide be positioned above the operator. If in doubt follow the procedure for Tramming as previously described!
When moving to the next hole ensure that the bull hose can not be run over with the drilling rig and that hole markers are not moved with the Bull Hose.
Following these set procedures throughout the working day and working to a system makes a very productive operation.
Constantly check drill steels, couplings, Bits and the shank for wear during the working day.
Never use worn-out couplings. steels, bits and shanks with lesser-worn parts of the Drill String as this will cause lockups of the couplings, drill steel and shank.
Rotate the drill string if required. It is a good practice to rotate the drill string from new, which will ensure even wear throughout the life of the consumables.
Never try to redrill a hole with drill bit larger than the one that drilled the hole.
15: Upon finishing drilling for the day.
Walk (Tram) Air Track back to compressor if it is not in a secure position reattach it to the compressor. Place the Drill Guide firmly on the ground and apply brakes to air track, close all air taps and valves, Always Idle the compressor for at least ten minutes to allow it to stabilize and cool down.
Upon shutting down the compressor, top up the compressor fuel tanks as condensation can form over night in the empty fuel tanks and can cause problems with fuel injection systems. In some circumstances where high Humidity is present it may be required to frequently change fuel filters and insert an additive into the fuel tanks.
Check all exhaust weather flaps to make sure they are in a closed position.
TIP!
Some times it is a lot easier to grease the Drill Rig at the end of a shift, as the grease becomes more fluid as the heat of the day progresses.
This can be done while the compressor is being Idled Down as ten minutes usually is sufficient to grease the main Grease Points.
Lockup and Secure Drill Rig and Compressor for the next shift or days drilling.
Any Barriers that have been moved or are required to accommodate the Drilling operation ensure that they are in place.
16: Care and Maintenance
Always keep the drill site clean and tidy to avoid the hazard of tripping or falling over.
Always use approved Oils & Greases specified by the manufacture for the safe
Operation of the described machinery.
Do Not use a hammer to break couplings, as Slivers of steel can become airborne. These slivers can penetrate the skin or an Eye (Hence Eye Protection Must Always be Worn).
If this procedure is required the thread or coupling is worn and ready for Reconditioning or Renewing.
It may also be possible that a dull Drill Bit has been used and high rotational speeds were used causing the Drill Steels to bind.
Regrinding of Cross x Bits
When the penetration rate slows to 75 percent of that of a new or reconditioned bit or when a flat of 2.4mm can be measured at the crest of the carbide tungsten it is time to recondition the drill bit.
Generally a bench grinder using a vitrified silicon carbide grinding wheel rated at the speed of the grinder should be used.
NOTE!
The use of a grinding wheel rated for speeds less than the actual operating speed of the grinder can result in serious bodily injury.
Always use Safety Goggles and Heavy Gloves when Sharpening Cross X Bits
Using the correct type of grinder with a threaded stem, the angle is adjusted (Generally 110 degrees) and the wheel is drawn across the carbide. This operation is repeated 8 times until all of the faces of the carbide have been sharpened. A new bit should be kept on hand as a model for the operator.
Associated problems with sharpening Cross X Bits
OVERHEATING.
Applying too much pressure when grinding.
Using a too hard or an incorrect type of grinding wheel.
Bits that have been over heated are too hot to hold after grinding and the carbide shows Bluing or Burn marks.
OVERGRINDING
Overgrinding the Bit wastes carbide and cuts down on the overall Bit Life.
Signs of overgrinding are: Sharp carbide edges.
: Significant reduction of carbide height.
CARBIDE TOO SHARP
Carbide should be ground to an angle of 110 degrees.
Carbide that is ground to sharp an angle will break prematurely.
CARBIDE TOO FLAT
Carbide that is ground to angles greater than 110 degrees blunt very quickly.
Drilling with Bits having to flat an angle will cause high stress in the Drill String,
Resulting in premature accessory Failure.
CHIPPED CARBIDE INSERTS
Portions of the carbide that have been chipped should be ground until the chipped area is not visible
SHARPENING OF BUTTON BITS
This procedure is far simpler than sharpening Cross X Bits.
Usually a portable air grinder is set up on a bench with a threaded stem.
The Air Grinder is fitted with a cone shaped Grinding stone encrusted with industrial diamonds; these grinding stones come in various sizes in order to suit the different size buttons. Water is injected through the center of the grinding stone to keep the stone and buttons cool.
The grinding stone is placed over the button with enough pressure to cut the carbide tungsten buttons.
Safety Goggles, heavy gloves and waterproof clothing are required for this type of operation.
There are special Sharpening Stations that can be purchased where the Button Bits can be sharpened from outside a sealed container and several buttons can be sharpened at the same time, and can be sharpened with afar greater degree of accuracy.
RECONDITIONING SPIRAL DRILL STEELS
The advantages of using spiral drills steels against single life drill steels is that the worn part of the spiral thread can be cut off with a cut off machine and chamfered at 30 degree, generally at the most 100mm off each end of the Drill Steel has to be cut off.
17: Environmental Hazards
Should the Dust Collection System not be efficient enough Particle Masks should be used or equivalent as the silicon content in Rock Dust can cause Health Problems with your Lungs IE: Silicosis, asthma etc.
Suitable work clothing should always be worn as High Exposure to the Sun (UV) can cause many health problems including Skin Cancer, SLE (Lupus) etc;
A suitable sunblock should also be used.
In a lot of Quarry operations Rubbish tips are operating in the quarry or adjacent to the Boundary, any ground water that comes out of the Drill Hole must be considered as contaminated. Do Not use this water for drinking, cleaning or put into the Air Track water tank.
When on a Drill Site always be aware of your surroundings and location to where you are standing and or operating your machinery. IE: Standing too close to the crest of a face or operating near a haul road.
If operating near a haul road place either signage , Barricades or Both so that you are visible to other operators.
Barricades should also be placed near the crest of the face so that the location of the face can be easily recognized.
DO NOT DRILL NEAR OR IN BLAST HOLES THAT CONTAIN EXPLOSIVES OR YOU SUSPECT THAT THEY MAY CONTAIN EXPLOSIVES.
Guidelines are setout in the explosives act and the Metallferous Mining Regulations as to what distance is recommended to drill in these situations.
Drilling into a Charged Blasthole could result in the Charge being initiated.
Unauthorized Personnel should not be allowed to operate or be near the operating machinery, All Authorized Personnel must be wearing the appropriate safety equipment.
Ear Plugs or Ear Muffs should always be worn while the Drill Rig is in operation as the Drifter noise can reach up to 120 dB + and more when the couplings are being broken out.
DO NOT OPERATE THE DRILL RIG IN STORMING CONDITIONS.
The Drill Mast can act as a lightning rod.
On the approach of a storm if possible lower the mast, shutdown the compressor and retreat to a safe location.
DISCLAIMER
All information supplied with this document is based on experience in the Mining and Quarrying Industries and might or mightn’t be suitable for some operations. The author accepts no Liability or Responsibility for use or misuse of information supplied herein.
As with all Drilling & Blasting Operations commonsense and awareness of your surroundings must always prevail.
Les Reeves
