77
Operation
SP 500 / 750-15 / 750-18 / 1000 / 1250 Operation Manual
Pumping the Job
Operate this machine from the ground to avoid falling
and other possible hazards.
If you cannot see the point of discharge from where you
are operating the unit, be sure your spotter is in position
before you start the pump.
As soon as the spotter gives you the start signal, put
the pump in forward and alert the ready-mix driver to
start dumping.
You cannot completely empty the
hopper, because air will be drawn
into the concrete cylinders. This air
will compress during the pushing
stroke and explode into the hopper
when the transfer tube switches
Figure 20
Concrete exploding from hopper
Concrete must always cover the openings of the mate-
rial cylinders so air will not be sucked into the material
cylinders. If that occurred, concrete would be rapidly ex-
pelled as compressed air escaped on the next stroke.
This can be extremely dangerous, so be sure the ready-
mix driver understands the situation. If air has entered
the material cylinders, you can cushion the expulsion
by stopping the concrete pump and lling the hopper
with concrete before the next stroke. When the hopper
is full, it is still not safe to resume pumping. Even with
the hopper full of concrete, some compressed air will be
introduced into the delivery pipeline. When it reaches
the discharge point, the air will cause the concrete to
be expelled forcefully. If the hose handler is walking a
wall or column or is in another precarious position when
this occurs, an accident could easily occur. It is best to
avoid ever sucking air into the material cylinders. If you
do accidentally suck air into the material cylinders,
warn the hose handler and clear the immediate area
around the hose until the air is released and con-
crete is owing steadily.
Point out the emergency stop buttons to the driver if you
will be standing somewhere other than at the operator’s
panel. That way, the driver can warn you or stop the
machine if he sees a dangerous situation developing.
Always keep an eye on the point of discharge or on your
spotter. If the hose person is giving you signals, he will
have his hands full and will not be able to jump up and
down or wave his hands to get your attention. On a typi-
cal job site, it is doubtful that you could hear him yelling.
As the day progresses and the crew removes pipe
sections from the end of the slickline, wash the pipes,
clamps and gaskets with water as soon as possible. If
you do not wash them until the pour is nished, you will
not be able to get the hardened concrete out of them.
This job can be done between loads of concrete, or by
an oiler or laborer at almost any time.
Figure 21
Wash system as it’s removed
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