Bailing Velocity Requirements; Hydrocyclone Set Up - Qlx 100; Maximim Fluid Removal Capacity; New Bit And Chuck - Atlas Copco Secoroc QLX Series Operator Instructions Manual

SETUP CHOKE PLUG
Before the DTH hammer is used to drill it should be set up for
proper air consumption and the joints should be tightened
. The selection of choke size will be dependent on the hole
cleaning requirments and the capacity (pressure and flow) of
the compressor being used. Hammer air comsumption should
be set up for the best balance of power and hole cleaning. Other
factors which need to be considered are depth of hole, water to
be encountered and water to be injected. In some cases, where
such factors are inpredictable , the proper choke size can only be
selected after experience is deleveloped.
The best performance of any DTH hammer will be achieved
when a maximum volume of air can be passed through the
drill with a solid choke. Under ideal conditions the pressure
required to drive this volume through the drill will be within the
capabilities of the compressor. QLX
plug which can be changed for additional hole cleaning capacity
if additional hole cleaning air is needed and compressor capacity
is sufficient. "Solid" choke plugs are installed from factory.
It should be noted that opening choke plug does create a back
– pressure on the DTH hammer which reduces performance.
Additionally, excess air which is not needed for hole cleaning
increases the wear of the DTH hammer.
Therefore, for cases where additional air is not required for hole
cleaning, consideration should be given to reducing compressor
output by lowering engine RPM or restricting the compressor
inlet.
If additional choke plugs are installed, install as shown.
*Except for QLX 35 and QLX 40.

Bailing Velocity Requirements

The need for adequate hole cleaning cannot be emphasized
enough. A hole that is not cleaned properly can result in poor
performance, rapid wear of bits and accessories and in some
cases loss of the drill and pipe down the hole. Hole cleaning is
usually directly related to what is called bailing velocity or the air
which is lifting cuttings from the hole.
Bailing velocity is defined as the velocity of the air in the hole
annulas at atmospheric pressure. In other words, the effect of
bottom hole pressureis not taken into account when computing
bailing velocity. For conventional hole cleaning (no soaps or
foams) bailing velocity should exceed 3000 ft/min (914,4 m/min).
However, if possible, bailing velocity should not exceed 7000 ft/
min (2133 m/min).
Bailing velocity can be computed by dividing the air
consumption of the DTH hammer in scfm by the annulus area in
square feet. The equation following may be used:
VELOCITY [ft./min..] (m/min.) =
AIR CONSUMPTION [scfm] (m3/min)
ANNULAS AREA [sq.ft.]
hammers* have a choke
(sq. m)
Where:
• Air consumption is the rate delivery of the compressor or the
air consumption of the drill at maximum pressure, whichever is
less.
• Annulus area is the area between the hole bore and the drill
rod. It can be computed as follows:
Annulas area:
[sq. ft.] = .0055 x (hole dia. [inches]squared - rod dia. [inches]
squared)
[sq. m) = .785 x (hole dia. [m]squared - rod dia. [m]squared)
Hydrocyclone set up – QLX 100
The Hydrocyclones are shipped with metering orifices which
regulate the amount of water which can be removed from the
air stream. The highest efficiency occurs when all the water and
very little air passes through the metering orifice.
Maximim fluid removal capacity (gallons
per minute)
The hydrocyclone (HC) separator metering orifice size (inch)
0.250 (1/4'').
Quantity of meterings ports (one open from factory, one partial
from factory).
Operating pressure (psig)
150 psi / 1 port = 16.0 gpm / 2 ports = 32.0 gpm
175 psi / 1 port = 17.3 gpm / 2 ports = 34.5 gpm
200 psi / 1 port = 18.5 gpm / 2 ports = 36.9 gpm
225 psi / 1 port = 19.6 gpm / 2 ports = 39.2 gpm
250 psi / 1 port = 20.6 gpm / 2 ports = 41.3 gpm
275 psi / 1 port = 21.7 gpm / 2 ports = 43.3 gpm
300 psi / 1 port = 22.6 gpm / 2 ports = 45.2 gpm
325 psi / 1 port = 23.5 gpm / 2 ports = 47.1 gpm
350 psi / 1 port = 24.4 gpm / 2 ports = 48.9 gpm
375 psi / 1 port = 25.3 gpm / 2 ports = 50.6 gpm
400 psi / 1 port = 26.1 gpm / 2 ports = 52.2 gpm
NOTE: Bypass orifice in Hydrocyclone must be able to pass
quantity of water injected at operating pressure. Failure to
adjust orifice to correct size will result in loss of power and DTH
hammer performance.

New bit and chuck

The QLX 100 uses plastic drive pins which insure a non-metallic
chuck to bit interface. These pins must be installed prior to
operating hammer. If the drive pins are omitted or fail, the chuck/
bit spline surface can operate reliably but ONLY for a short
period of time.
Chuck threads should be well coated with thread grease before
threading into casing. Remembering to install bit retaining rings.
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