Schwing SPB 28, Operation Manual

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77
Operation
SPB Operation Manual
Cleaning the vertical pipeline
Compressed air hazard! Always use
at least two qualified people to blow
out a vertical pipeline and secure the
discharge.
The outlet must be controlled
Discharge pipe must always consist of only slickline.
Never use rubber hoses when blowing out with com-
pressed air.
When the pour is completed and the concrete pump
is no longer needed, the pump operator should be in-
structed to close the concrete shut-off valve and discon -
nect the pump from the delivery line. After disconnect-
ing the line there are several options. The man on the
ground will either hook up the discharge line and direct
the elbow into whatever vessel will be receiving the dis-
charge or attach one of the two possible catch baskets
to the end of the pipeline (Figure 43).
Any discharge line that is connected to the verti-
cal pipeline for the purpose of cleaning out must
be lubricated with slurry to prevent any blockage
which might be caused from pumping into a dry
pipe.
If the line is being diverted to a holding vessel, like a
mixer truck or a crane bucket, the discharge end should
then be secured with adequate safety cables or chains
and covered to prevent concrete from escaping when
the ball is expelled.
If a catch basket will be used, The concrete should be
chased with a go devil instead of a sponge ball. The sys-
tem must still be secured and the proper catch basket
attached. The catch basket must be elevated enough to
be clear of the concrete pile when finished and should
still be covered to prevent the spray of concrete to the
surrounding area. There are two types of catch baskets.
One is shorter than the go devil and one is longer. Each
type has advantages and disadvantages (Figure 43).
Short basket
AIR
PRESSURE
1
Advantage:
There is no turbulent expulsion of air.
Disadvantage:
Air remains in the line, because it
cannot pass the go devil. The line must not be
opened until all air is drained at the blow out head.
Advantage: All compressed air is relieved with the
expulsion; the pipe may be opened immediately.
Disadvantage: There will be a turbulent
expulsion as the air escapes.
Long basket
AIR
2
AIR
PRESSURE
Figure 43
Two types of catch baskets
Blowing out the line
The ball or go-devil should be inserted at the top of the
vertical pipeline and an approved blowout cap installed.
The blowout cap must have an air regulator valve
for air inlet as well as one for air discharge. The
two valves must be far enough apart to prevent
the ball or go-devil from being able to block both
of them at the same time (Figure 44). This will al-
low you to relieve pressure and open the pipe-
line, if necessary.
An adequate air compressor should be connected to
the water/air inlet of the blowout cap.
When the operator on the ground indicates that he has
cleared the discharge area of personnel and is ready
for concrete, he will inform you that the air supply to
the blowout cap can be opened and will then open the
concrete shut-off valve. Many qualified people have
their own ideas about how to control the flow and speed
of the concrete at this point, but we at Schwing rec-
ommend that the air supply be turned off as soon as
the concrete begins to move and feathered lightly as
needed to keep it moving. The person on the ground