Del. Code tit. 16, § 7312

1-K and 2-K kerosene which is kept, offered, exposed for sale or sold within the State shall be properly identified as meeting A.S.T.M. standards. Such identification requirements shall apply to every dispenser and delivery ticket (manifest or invoice) accompanying the transfer of kerosene which is kept, offered, exposed for sale or sold in the State. Furthermore, dispensers or retail pumps of kerosene fuels other than 1-K must bear the following warning label in a conspicuous place: A.S.T.M. grade 2-K kerosene is not suitable for use in unvented (flueless) portable heaters. Evidence for the quality of 1-K or 2-K from the supplier of kerosene shall be maintained at the retail sales location and shall be available for state inspection during normal business hours.