Atlas Copco SECOROC COP 84.2L Manual - Página 8

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1. Technical Data

Drilling in wet holes

The inﬂ ow of water into the drill hole is expected when drilling water

wells, but can also occur when drilling deep holes for other purposes.

Water inﬂ ow does not normally create problems for drilling, although

both "too little" and "too much" can be troublesome.

Too little water tends to bind the drill cuttings into a paste, which sticks

to the drill pipes or the hole wall and can easily form collars or plugs.

The problem can be lessened by adding water to the ﬂ ushing air, thus

increasing the ﬂ uidity of the cuttings. Fluidity can be further improved

by adding washing detergent to the water.

N.B. Remember to increase the lubrication dosage when injecting

water into the ﬂ ushing air!

If the inﬂ ow of water is so great that it restricts the bailing of cuttings

and water from the hole, then extra ﬂ ushing will be needed. See Extra

ﬂ ushing, page 7.

Water injection

Water injection is normally used to suppress dust when drilling dry

holes. COP down-the-hole hammers are designed to function with a

certain amount of water injection. As an example, only 2—6 litres of

water per minute (at 18 bar air pressure), injected into the main air line,

is sufﬁ cient to control the dust when drilling with the COP 64. Too much

water injection will have a very negative inﬂ uence on the penetration

rate of the hammer.

Rule of thumb: 0.25 l water per m

the hammer during the drilling sequence.

Flow chart for water ﬂ ushing

A = Main inlet valve on drill rig

B = Container for air tool oil

C = Filter

D = Lubricator valve

E = Pressure gauge

F = Check valve

G = Valves

H = Water pump

CAUTION

The injection point for water and foaming concentrate should always be

located after the main shut-off valve on the rig. If not, there is a danger

of the mixture being pumped back through the main air line and into the

compressor. This could seriously damage the compressor.

Foam injection

Foam can be used in DTH drilling to improve the ﬂ ushing performance

(especially in non-consolidated formations). It does this by "lifting up"

the cuttings out of the hole, and also has the desir able effect of sealing

the hole walls. Foaming concentrate is pumped into the compressed-

air line in the form of a concentrate/water mixture. Atlas Copco foam-

ing concentrate has lubricating properties and contains corrosion

inhibitors, which prevent seizing in the hammer.

N.B. Before using foaming concentrates not supplied by Atlas Copco,

please consult your Atlas Copco representative for advice.

With Atlas Copco foaming concentrate, a mixture of 0.5–2 per cent

concentrate/water is normally recommended. When drilling in water-

bearing rock and other difﬁ cult formations, it might be necessary to

increase the percentage of concentrate, and also to add polymers to

the operating air. This will help to stabilize the hole walls and increase

the lifting capacity of the foam. The concentrate/water mixture is

injected into the main air line by means of a high-pressure pump.

com pressed air consumed by

K = Water tank

N = Compressor

O = DTH-hammer

Optional

L = Separate foam pump

M = Separate foam tank

Minimum requirements for the water-injection pump are as follows:

min. pressure = 30 bar

min. ﬂ ow = 20 l/min.

After drilling with foam, it is recommended that residual foam should

be ﬂ ushed out of the hammer to prevent corrosion. This is done by

injecting water only into the air, and so ﬂ ushing the foam out the

hammer. Oil should then be poured into the drillstring and the hammer

operated for a few minutes before the drill string is withdrawn from the

hole. If the hammer is then to be stored for a long time, it should be

dismantled and all parts cleaned and oiled thoroughly.

Tools

Tools for removing the drill bit and top sub

from the DTH hammer

The threaded connections of the driver-chuck and top sub can become

very tightly tensioned during drilling. There are special tools for remov-

ing the bit and top sub from the cylinder of the DTH hammer, and these

should be used whenever possible.

Wrench for pipe-jointing

and top sub

Wrench ﬂ at

Ordering No.

55 mm

8484-0211-43

65 mm

8484-0211-00

95 mm

8484-0211-02

102 mm

8484-0214-13

120 mm

8484-0211-36

140 mm

8484-0211-44

Bit removal tool

Loosening the threads of the hammer

If special tools like chain wrenches or other types of wrench are used

to break the hammer joints, then the tool must be attached around

the hammer cylinder as shown in the ﬁ gure. Do not attach at other

points!

mm (in)

COP 34

140

(5.5)

(2.8)

140

COP 44

(5.5)

(2.8)

COP 54

180

(7.0)

(2.8)

COP 64.2/64.3 190

(7.5)

(3.1)

190

COP 84.2L

(7.5)

(3.1)

COP 84

200

(8.0)

(3.1)

DANGER

Take great care when breaking the driver-chuck joint using the bit

removal tool in combination with reverse rotation. If the shaft of the tool

is not locked or touching the edge of the feed beam, the shaft can turn

with great force when breaking the driver chuck joint.

Keep your hands and clothing well clear of the hammer/drill string

when it is rotated. Entanglement can result in serious injury.

Blows against hammer or bit can cause fragments of metal to ﬂ y.

Always wear goggles when breaking joints.

145

(2.0)

(5.8)

150

(2.0)

(6.0)

175

(2.0)

(6.9)

175

(2.4)

(6.9)

240

(2.4)

(9.4)

250

(3.1)

(10.0)