Abstract: A valve unit for controlling the delivery of a combustible gas, in particular for delivery via a gas metering apparatus including a main gas through-flow pipe (2), the unit comprising a servovalve with a first valve seat (3) provided on the pipe and associated with a respective first shutter (6) with diaphragm control (7) for the opening of the seat (3) in opposition to a first return spring (22), an operating chamber (10) for controlling the servovalve, the chamber being in communication with an inlet section (4) of the main pipe (2), upstream of the first valve seat (3), one side (7a) of the diaphragm (7) being subjected to the pressure prevailing in the chamber (10), the other side (7b) being subjected to the pressure prevailing downstream of the first valve seat, in the region of an outlet section (5) of the pipe (2), the operating chamber (10) being in communication with the outlet section (5) via a second valve seat (9) co-operating with a second shutter (8).

Abstract: A system for the leaktight connection of a valve unit to a respective pipe, is provided. The valve unit includes a gas through-flow section, a threaded male attachment element being formed integrally with the valve unit and having an axial through cavity defining the gas through-flow section, for leaktight clamping by a pipe-fixing ring-nut connector which can be screwed onto the male threaded portion of the attachment element. The system includes a second leaktight connector which can be put into operation as an alternative to the ring-nut connector. The second connector including at least one axial retaining element which can be releasably restrained on the valve unit in the region of the threaded portion of the male attachment element, in a manner such that the pipe is restrained axially relative to the valve unit.

Abstract: A valve unit comprises a single electromagnetic actuator for controlling both an ON-OFF valve for cutting off the gas and a modulation valve; the latter is subject to independent resilient loads for regulating the minimum pressure delivered and for regulating the pressure up to the maximum pressure at the modulation stage.