Ключевые слова: blue, business, butane, chemistry, cold, concepts, conservation, container, danger, day, dirty, energy, environmental, equipment, fossil, fuel, gas, generation, green, heat, horizontal, industrial, industry, liquid, metal, natural, nobody, outdoors, petroleum, pipe, pipeline, power, pressure, propane, risk, rural, rust, rusty, safety, scene, sign, sky, steel, storage, supply, tank, technology, tube, valve, white,