once he has been 「detected」, shop keepersrefuse to sell to him (it is illegal to sell butane gas in largevolumes without a license).
一旦被人发现,商店将不会卖给他(销售大量的甲烷气体是违法的,除非出示购买去可证)。
the liquidized butane gas can be heated at any time by an electric heating rod inserted into the gas storing tank, and the welding gun can be operated normally under different temperatures.