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i'm aaron feldman, investigations officerwith worksafebc. inside the pipeline of a concrete pumper,air can get trapped and compress to hundreds of pounds per square inch of pressure. the release of this air can cause the hoseto suddenly whip. here, that cost one worker his life.

hire car uk australian licence, two workers had just completed a porch usingconcrete supplied by a pumper truck. the truck's pump was stopped and its boomwas relocated to pour a walkway. one of the workers held the end-hose overthe concrete forms. the concrete pump operator restarted the pump.

he saw that the concrete wasn't flowing. realizing there must be a blockage, he immediatelyhit the emergency stop button. the blockage suddenly cleared. concrete and air burst out, whipping the hose. the worker's heel caught on a piece of formwork. he then fell and struck his head on a 2 by10. the worker did not survive his injuries. a hose whipping hazard is created if air getsinto a pumper's delivery system and is compressed against a blockage.

air can get into a pipeline if the pump isstopped while the boom tip is in the down position. that's what happened here. after the porch was poured, the pump was stoppedwith the boom tip down. concrete was allowed to drain out of the last section of the boom. concrete in the system then likely flowedback to the pumper's hopper, sucking air in through the end-hose. now inside the pipeline there was a pocketof air. restarting the pump pushed the concrete forward,compressing the air pocket like a spring against

the blockage. propelled by the pump and the compressed air,the blockage moved faster and faster through the pipeline. seeing no flow, the operator pushed the emergencystop -- but it was too late. the air and concrete blasted out, causing the hose towhip. hose whipping accidents can be prevented. before starting a pour, warn workers of thehazard of hose whipping. train workers to prevent blockages in pipelinesand to recognize situations when air can get trapped behind a blockage.

to minimize whipping, end-hoses should beno longer than allowed by the manufacturer. a coupling should not be on the dischargeend. the hose on this pumper was 20 feet long -- 8feet longer than allowed -- and it had a

coupling on the end. hose whipping is a serious hazard. if you restart a pump after the boom tip hasbeen down, ensure that workers stay clear of the end-hose until the concrete is flowingsmoothly.