The Senate approved legislation to lift price controls on natural gas, a move supporters say will help ensure adequate supplies of the fuel used by 48 million American households, even if consumers must pay more. The vote was 82 to 17 after the bill's chief opponent, Sen. Howard M. Metzenbaum (D-Ohio), failed to win approval of four amendments that he said would protect consumers from what he called a certain trend toward higher prices. The House passed a similar bill in April on a voice vote with little debate. A House-Senate conference committee will seek to reconcile the two versions and send a final measure to President Bush, who strongly favors gas decontrol. The legislation calls for lifting the price controls on Jan. 1, 1993.