Operation
30
7/27/12
Operation Manual - SP 305
back to reverse and relieve the pressure in the line.
See the information in this manual about removing
plugs from lines starting on page 34.
• Once the concrete comes out at the discharge point,
move yourself into position to see the discharge.
Remember, you must also be able to see the pump,
so arrange for a spotter if you cannot. In some
circumstances, it is allowed to have the ready mix
driver monitor the pump end of the job. If you will
be allowing it, you MUST be sure that the ready
mix driver understands how to stop the pump and
what will happen if air is allowed into the delivery
line. The ready mix driver may refuse the
responsibility of watching the pump. If this
happens, you will still need to arrange for a spotter.
Because of the risk of injury to the ready mix
driver and the placing crew if air is introduced into
the delivery system, the hopper level must be
monitored at all times. If the ready mix driver will
not do it, you must still arrange that it be done
(Figure 20).
• Adjust the volume control knob as needed for
faster or slower pumping.
• Watch the hose handler closely. Be ready to stop
the pump when required. Kinking a placing hose
while pumping can be dangerous, because it causes
the pump to go to maximum pressure, simulating a
blockage. If you see that the placing crew is
kinking the hose, stop pumping and talk to them
about it.
• Keep an eye on the pump. Listen for engine
bogging (a sign of plugging). Watch that no one,
especially children, get near the unit.
• When the ready-mix truck is empty, the driver
should signal you by voice or horn. If you have
shown the driver how to stop the pump, you could
also be signaled that way. In addition, an
experienced pump operator will be able to tell by
the sound of the rotating drum that it is almost
empty. The remaining larger aggregate in an
almost-empty drum falls from the fins, and instead
of hitting on concrete, it hits on steel, making a
distinctive sound. Be aware to listen for these
clues, so that you can stop the pump with a full
hopper. (You will need a full hopper so that you
can keep the concrete moving if you have to wait
for the next load.) If no more concrete will be
coming, such as at the end of the pour, try to end
up with only about a third of a hopperful.
WARNING!
You cannot completely empty the
hopper, because air will be drawn into the concrete
airhop1.eps
Figure 20
Do not allow air to enter the
pumping cylinders. Keep the
hopper full when pumping.
minimum 4 inches above
material cylinder opening
Svlvminlev.eps
To Next Page
Loading...
