Pressure regulator for the regulator first stage of a two-stage aqualung

Pressure regulator for the regulator first stage of a two-stage aqualung, comprising a reduction chamber (501; 901) which communicates, via a delivery valve (401), with an admission channel (101) for admitting the high-pressure mixture of breathable gases, and with at least one outlet (701) connected, via suitable connection means, to a regulator second stage, there being a flexing chamber (801) for an elastically deformable diaphragm (2) connected to a rod-shaped control member (431) of the delivery valve (401), and there being an annular choke (621; 921) allowing axial sliding of the said member (431) and obstructing the direct flow of gas between the said reduction chamber (501; 901) and the said flexing chamber (801), characterized in that the regulator is provided with a channel (811) which connects the said reduction chamber (501; 901) with the said flexing chamber (801), flow adjustment means (821) being provided in the said channel.