A method for evaluating a quasi-stationary pressure difference detectable by a sensor at a gas boiler. The gas boiler has a mixing device (4), a fan (5), a main flow regulator (3), a control valve (2) and a safety valve (1). The sensor detects a differential pressure between a pressure (p2) at a measuring point upstream of the main flow regulator (3) and downstream of the control valve (2) and a reference pressure (p0, p1) at a reference measuring point. The sensor transmits a signal to an electronic evaluation system. The electronic evaluation system compares the differential pressure during a pre-purge phase, wherein the safety valve (1) is closed, with the differential pressure after the pre-purge phase and detects an error by the comparison.

A printing cylinder assembly for detecting existing and/or developing errors during printing comprising at least one printing cylinder which is suitable for printing on a material, and has at least one cylindrical body, at least one shaft forming a rotational axis for the body, and characterized by the printing cylinder which has at least one cavity extending from the surface of the body towards its interior volume, at least one sensor which is suitable for being placed in the said cavity, at least one communication interface which is suitable for communicating with an external device, at least one control unit which is adapted to receive data from the sensor, and transfer these data to an external device via the communication interface directly and/or by processing them, and at least one power supply which is for supplying the power needed by the sensor, the communication interface and/or the control unit.

A fuel gas supply apparatus includes: a pressure reducing valve that reduces, to a preset pressure, a pressure of fuel gas supplied from a tank that stores the fuel gas; and a supply amount adjustment unit that adjusts, by selecting a fuel supply channel passing through at least one of two orifices that are provided on a downstream side of the pressure reducing valve and have different orifice diameters, a supply amount of the fuel gas from the fuel supply channel. According to the fuel gas supply apparatus, a mechanism for suppressing pressure fluctuations of the fuel gas is unnecessary, and thus the entire fuel gas supply apparatus can be accordingly reduced in size.