In general, a change in claim category from a method in which an apparatus is used to the apparatus itself is not allowable (see T 86/90).
However, it may exceptionally be allowable to replace a claim directed to a method of operating a device by a claim directed to the device itself if the original claim contains the claimed features of the device exhaustively, whether in structural or functional terms (see T 378/86 and T 426/89).
This exception, however, does not apply if the device as now claimed is for its features no longer dependent on the circumstances of its operation whereas it depended on them under the terms of the prior method claim (see T 82/93).
Moreover, changing the category from a purpose-limited process claim in the format of a Swiss-type claim in accordance with G 5/83 to a purpose-limited product claim in accordance with Art. 54(5) contravenes Art. 123(3), because a purpose-limited process claim confers less protection than a purpose-limited product claim (T 1673/11).