Visualize when you are about to finish the job. If you have a full hopper and 200 feet of hose, you know you have about a quarter of a yard or 5 wheelbarrows. So when the job is about 5 wheelbarrows from completion, stop pumping.
Go over the mixer truck driver to let him know he can stop pouring concrete into the machine, and can start washing down his equipment.
Pump the hopper down as low as it will go.
Fill the hopper with water and start pumping again so that you can use the water to push the concrete left in the hose. Otherwise you will be pumping just air and the hose will not come clean.
Go to the guys holding the hose and instruct them that as soon as they see water, to stop.
Once the hoses are free of concrete, disconnect JUST THE HOPPER from the hoses.
Wash the hopper and stick the concrete pump cleaning sponge ball in the reducer. Fill the hopper full of water to push the cleaning sponge down the system, cleaning all the hoses. Make sure to use a sponge ball one size bigger than the hose. For example use a 4″ ball for a 3″ hose.
When the ball comes out the other end, clean the ends of the last hose used and disconnect the system.
l Post-concrete-pump-cleaning maintenance: Grease the machine after every job, dump the water box and look for dirty water especially any oil in the water, as well as loose pistons and loose connecting rods. This protects your investment and makes using a concrete pump require fewer repairs and less downtime.
l using a concrete pump set up clean up manual, like the one here