CLEAN AIR Title and commencement 1 These regulations may be cited as the Clean Air (Emission of Grit and Dust from Furnaces) Regulations 1971 and shall come into operation on 1st November 1971. Interpretation 2 1 In these regulations— “ indirect heating appliance ” means a heating appliance in which the combustion gases are not in contact with the material being heated ; “ multiflue chimney ” means a chimney structure which for the whole or the greater part of its vertical length carries separate flues from more than one furnace ; and “ schedule 1 furnace ” and “ schedule 2 furnace ” mean respectively a furnace described in schedule 1 and a furnace described in schedule 2 to these regulations, being in either case a furnace to which section 2 of the Clean Air Act 1968 applies . 2 The Interpretation Act 1889 shall apply for the interpretation of these regulations as it applies for the interpretation of an Act of Parliament. Postponed application of regulations in certain cases 3 The provisions of these regulations shall not apply until 1st January 1978 to any furnace which has been installed, or the installation of which has been begun, or an agreement for the purchase or installation of which has been entered into, before the commencement of these regulations. Limits on emission of grit and dust from certain furnaces 4 1 The quantities of grit and dust which may be emitted during any period from the chimney of a schedule 1 furnace or a schedule 2 furnace with a heat output or input which is within the highest and lowest values specified in column (1) of the relevant schedule shall not exceed the quantities prescribed by that schedule. 2 For the purposes of this regulation, where a chimney serves more than one furnace— a if it is a multiflue chimney, each flue shall be taken as a separate chimney serving a separate furnace; and b in any other case, it shall be taken as a single chimney serving a single furnace with a heat output or input equivalent to the aggregate of the heat outputs or inputs of the furnaces concerned; and for these purposes any part of the emission which derives from a furnace to which these regulations do not apply shall be disregarded. 3 The provisions of the next following paragraph shall have effect for applying the foregoing provisions to cases where the rating of a schedule 1 furnace or the heat input of a schedule 2 furnace is a value intermediate between two adjacent values in column (1) of the table in that schedule. 4 In a case described in the preceding paragraph, the prescribed quantities in respect of the chimney of the furnace shall be arrived at as follows:— a by interpolating the intermediate value into column (1) of the table between the two adjacent values (in this paragraph called “the two values”); b by calculating the interval between the lower of the two values and the intermediate value as a proportion of the interval between the two values, carried to two places of decimals; and then c by interpolating a figure, likewise carried to two places of decimals, into column (2) or (3), as the case may be, against the intermediate value at the same proportionate interval between the quantities prescribed in that column against the two values. Circumstances in which the prescribed limits apply 5 These regulations shall apply to a furnace in respect of any period of standard operation, that is to say, any period during which the furnace is operating— a at or close to the loading to which it is subject for the greater part of its working time or b at any higher loading to which it is regularly subject for a limited time (whether or not that loading exceeds its Maximum Continuous Rating or designated heat input). Regulations not to apply to incinerators 6 These regulations shall not apply to any incinerator, that is to say, to any appliance used to burn refuse or waste matter, whether solid or liquid, and whether or not the resulting heat is used for any purpose. Peter Walker Secretary of State for the Environment 1st February 1971