When I worked at RBC in Rhodesia we had, as a vacuum cleaner of sorts, a large centrifugal blower with a bag attached to the blower end and a hose on the suction end. Occasionally it was used as a source of compressed air to blow out dust from equipment. On this one occasion a tech was using it as a blower and he was wearing a tie. I heard the machine "stumble' and die followed by a gurgling sound and turning from my job noted the tech with the machine up against his chin and his face going blue. I always carry a pocket knife and in a short time I had hacked his tie to shreds and retrieved his breathing and the machine. His tie had been sucked into the inlet and wrapped around the impeller until it ran out of tie and attempted to pull his neck in. While he caught his breath and lamented over his tie I dumped the said machine into the garbage bin and wrote an addendum to the shop rules that hence forth not ties were permitted in the shop. We purchased a proper vacuous shortly after.