Schwing SPB 28, Руководство по эксплуатации

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74
Operation
SPB Operation Manual
remember is that concrete begins to set as soon as it
becomes motionless. Every five minutes or so, give the
pump a stroke, which will make the concrete in the el-
bows and reducers change their shape, thus breaking
the set. Concrete setting in the boom acts like a block-
age. Blockages can be dangerous, because the pump
will create maximum pressure on the concrete.
Keeping the concrete alive
The operator should always keep the hopper as full as
possible. If you are waiting more than 15 minutes, re-
member that with an SPB you cannot keep the concrete
alive by swinging your boom around to cycle through
your own machine. If a long delay is imminent, it is im-
portant that you clean out the boom and pipeline before
the concrete gets a chance to set. A boom party with a
concrete pump is bad enough, but losing an entire ver-
tical pipeline and the boom is much worse, and a very
expensive mistake.
If you are waiting for a form to be finished or repaired, or
anytime that the delay has nothing to do with waiting for
concrete, you can give the pump one or two strokes in
five minute intervals for a longer period of time, because
the ready-mix truck will be able to refill your hopper. If
you cannot dump concrete on the deck or into the form,
or if you must wait so long that you’re not comfortable,
inform job site personnel that you must clean out the
delivery line.
Consider the age of the concrete in the ready-mix
trucks. If you have several trucks lined up waiting with
you, the concrete in those trucks is also beginning to
set. Let’s assume that you have been waiting for 45
minutes, and the ready-mix plant is 25 minutes from the
job. This truck was on the job 35 minutes before the
delay began. His concrete is now one hour and 45 min-
utes old. Depending on the temperature and the mix, it
may be risky to even consider pumping his concrete.
Only you can make that call.
Balance loads
It is an unfortunate truth, in many cases, that you will
have to wait for a “balance load” of concrete. This is
usually 1 or 2 yards that weren’t ordered by the con-
tractor until the last minute. It usually happens late in
the day, so typically 4 of the 5 ready-mix drivers that
you were seeing all day have gone home, and the same
man that brought the next to the last load will have to
go and get the balance load. On high rise applications
most contractors will finish the job with a tower crane to
avoid having to wait with concrete in the delivery pipe-
line. If they are not willing to do that, you must inform
them about how much time you feel you can wait for an
order back before you will need to clean the pipeline. Be
careful! With old concrete it is imperative that the boom
is cleaned immediately upon finishing the pour.
Cold Weather Pumping
Minimum temperature for boom operation is 5˚ F /-15˚C
The boom must not be used in Temperatures below 5
F (-15˚C) unless the manufacturer has given express
approval. There is danger of damage to the steel (brittle
fracture) and the seals throughout the system as well as
the accumulator at these extreme temperatures.
Cold weather pumping tips
It is possible (and routine in some parts of the world) to
pump concrete with outside temperatures as low as -10
degrees Fahrenheit and even colder. This can present
a variety of problems compared with pumping in mod-
erate temperatures, such as:
• The boom hydraulics are slow and sluggish to
respond to your commands.
• Slurry freezes in the boom when you are starting
the pour.
• Concrete can freeze in the boom.
• Concrete freezes in the hopper, down below.
• The concrete will be loaded with calcium chloride
or an equivalent chemical to allow the concrete to
set faster and prevent freezing. This will accel-
erate setting in much the same manner as a hot
day does.
• Anything you wash with water becomes coated
with ice, which will not melt until the temperature
rises above freezing.
• Machine parts that you sometimes stand on or
grasp with your hands become very slippery if
they contact any water.
Some of these potential cold weather problems can be
solved or tolerated, others cannot. A majority of the time
the concrete will be mixed using very hot water to keep
the concrete from freezing during the delivery and wait-
ing period. Even though most of the following tips apply
to concrete pumps in general and not just SPB’s, here