The Alkali, & c. Works Order (Northern Ireland) 1991

(8) (a) muriatic acid works or works (not being alkali works as defined in section 27(1) of the Alkali Act) where muriatic acid gas (hydrogen chloride) is evolved either during the preparation of liquid muriatic acid or for use in any manufacturing process or as the result of the use of chlorides in a chemical process;

(b) tinplate flux works in which any residue or flux from tinplate works is calcined for the utilisation of such residue or flux, and in which muriatic acid gas is evolved; and

(c) salt works (not being works in which salt is produced by refining rock salt, otherwise than by the dissolution of rock salt at the place of deposit) in which the extraction of salt from brine is carried on and in which muriatic acid gas is evolved.