Schwing SP 750-18 - Blockages

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Operation
SP 500 / 750-15 / 750-18 / 1000 / 1250 Operation Manual
Blockages
If you have a blockage in your pipeline that you cannot
remove by the backward/forward rocking motion (two
strokes in reverse, then go back to forward), you will
have to disassemble the pipeline to nd it. Before you
disassemble the pipeline, you must relieve the pressure
by pumping in reverse for several strokes.
• When you go to the pipeline to nd the block-
age, take your hammer with you. Wear all of your
personal protective devices for this procedure.
Most of the time, you will nd the blockage in a
reducer, hose, or elbow. The act of reversing the
pump will make the pipeline sound di󰀨erent when
tapped with a hammer than if it were pressurized.
“Tapped” is a key word here. You can damage the
pipe by striking it hard. You should be able to hear
the di󰀨erence. An empty pipe has a denite rever-
berating “tong” sound. A full pipe without pressure
will have a meaty “thak” sound, and a pressurized
pipe full of concrete will have a thin “tik” sound be-
cause the forces on the steel will not allow it to
vibrate. Once you have located the blockage,
carefully remove the clamps from the blocked
pieces. If you are not wearing a full face shield,
turn away from the clamp as you pull the han-
dle. If you have relieved pressure by stroking
in reverse, you should be ne, but sometimes
a blockage will store pressure because there is
another blockage upstream or downstream. It
is better to be safe than sorry. Once the clamps
are removed, the danger is past. Displace the
blocked piece enough that you can push a piece
of rebar or another long poking device into it. If the
blockage is in a hose, it will help to hit the outside
of the hose with the hammer. Again, do not dam-
age the hose by hitting it so hard that the steel
braids inside get permanently disgured. When
the blockage is loosened, elevate one end of the
pipe or hose and dump out all remaining concrete.
• Once the blockage is removed, clean up the
clamp, gasket, and pipe end with a rag or, in a
pinch, wipe the concrete o󰀨 with your hands (al-
ways wear rubber gloves when working with con-
crete. Reassemble the pieces, and pin the clamps.
Return to the pump and start pumping in forward
again, slowly at rst, until you are sure that there
are no more blockages. If you encounter another
blockage, relieve the pressure again by pumping
in reverse for several strokes before nding the
remaining blockages.
• Do not use compressed air to remove a blockage.
Your concrete pump has at least six times more
pressure available than an air compressor. If the
pump won’t push the plug, air certainly won’t. In
addition, air that is compressed builds a reservoir
of pressure that will continue to be dangerous
even when the compressor is shut o󰀨.