All installations of liquefied petroleum gas equipment, including such equipment installed at utility gas plants, shall be in conformity with generally recognized standards for safety to persons and property. Except as otherwise provided in this subchapter or in other laws or regulations legally in effect, conformity with the Standards of the National Board of Fire Underwriters for the Storage and Handling of Liquefied Petroleum Gases (Pamphlet No. 58), and in the case of liquefied petroleum gases at utility gas plants, conformity with the Standards of the National Board of Fire Underwriters for the Storage and Handling of Liquefied Petroleum Gases at Utility Gas Plants (Pamphlet No. 59), shall be prima facie evidence of conformity with generally recognized standards for safety to persons and property.