EMP WAS HANGING VENT LINE FROM A 2 YD LOADER AS WAS HIS PARTNER ON THE OTHER SIDE OF STOPR. PARTNER HAD KINK IN VENT LINE & ALL AIR RUSHED TO THE OTHER SIDE AND VENT LINE KNOCKED HIM OFF LOADE R TO THE SILL. HE LANDED ON THE LEFT SIDE OF HIS BACK & FRACTURED 2 RIBS.