Field device for process instrumentation

A field device for process instrumentation which is configured for use in areas subject to explosion hazards, comprising:

• a housing of the field device;
• an electronic unit arranged in the housing of the field device;
• at least one battery for supplying the electronic unit with auxiliary energy required for its operation;
• a housing part including a cover which is removable to replace the at least one battery;
• and
• a battery compartment disposed in the housing part;
• wherein the at least one battery comprises a replaceable standard battery and is arranged in the battery compartment disposed in the housing part;
• wherein at least one of the housing part to be opened and the cover includes a battery chamber for accommodating the at least one battery in a correct position;
• wherein a circuit for supplying the electronic unit with the auxiliary energy provided by the at least one battery is configured such that, when closing the battery compartment, the circuit is closed only when the housing part has already been closed by the cover such that the battery compartment meets a requirement for use in areas subject to explosion hazards;
• wherein, when opening the battery compartment, the circuit has already been opened before the housing part has been opened by the cover such that the battery compartment no longer meets the requirement for use in areas subject to explosion hazards;
• and
• wherein the housing part is closable with the cover by a screw closure, and wherein at least one electrical contact in the supply circuit is closable only when the screw closure has been screwed in such that the requirements for use in areas subject to explosion hazards have been met on account of its property as an ignition barrier or flame arrester.