Pressure regulator (2; 102; 202) for compressed gas, comprising: a body (4; 104; 204) with a gas inlet (6; 106; 206), a gas outlet (8; 108; 208) and a gas passage (10; 110; 210) interconnecting said gas inlet (6; 106; 206) with said gas outlet (8; 108; 208); a shut-off device (12; 112; 1.212, 2.212) comprising: a seat (14; 114; 1.214, 2.214) located in the gas passage (10; 110; 210); a shutter (16; 116; 1.216, 2.216) configured for cooperating the seat (14; 114; 1.214, 2.214); a pressure sensing assembly (18; 118; 1.218, 2.218) defining an internal volume (18.1; 118.1; 1.218.1, 2.218.1) filled with an auxiliary gas and closed by a plug (24; 124; 1.224, 2.224; 324.1, 324.2), said pressure sensing assembly being elastically deformable and located in the gas passage downstream of the seat (14; 114; 1.214, 2.214), said pressure sensing assembly being configured for actuating the shutter (16; 116; 1.216, 2.216) relative to the seat (14; 114; 1.214, 2.214) depending on a gas pressure downstream of the seat; characterized in that the pressure regulator (2; 102; 202) further comprises: a port (20; 120; 1.220, 2.220; 320) fluidly connected, via the plug (24; 124; 1.224, 2.224; 324.1, 324.2), to the internal volume (18.1; 118.1; 1.218.1, 2.218.1) of the pressure sensing assembly (18; 118; 1.218, 2.218), and configured for fluidly connecting an external source of the auxiliary gas to said internal volume (18.1; 118.1; 1.218.1, 2.218.1) for adjusting a pressure of the auxiliary gas in said internal volume. a body (4; 104; 204) with a gas inlet (6; 106; 206), a gas outlet (8; 108; 208) and a gas passage (10; 110; 210) interconnecting said gas inlet (6; 106; 206) with said gas outlet (8; 108; 208); a shut-off device (12; 112; 1.212, 2.212) comprising: a seat (14; 114; 1.214, 2.214) located in the gas passage (10; 110; 210); a shutter (16; 116; 1.216, 2.216) configured for cooperating the seat (14; 114; 1.214, 2.214); a pressure sensing assembly (18; 118; 1.218, 2.218) defining an internal volume (18.1; 118.1; 1.218.1, 2.218.1) filled with an auxiliary gas and closed by a plug (24; 124; 1.224, 2.224; 324.1, 324.2), said pressure sensing assembly being elastically deformable and located in the gas passage downstream of the seat (14; 114; 1.214, 2.214), said pressure sensing assembly being configured for actuating the shutter (16; 116; 1.216, 2.216) relative to the seat (14; 114; 1.214, 2.214) depending on a gas pressure downstream of the seat; a seat (14; 114; 1.214, 2.214) located in the gas passage (10; 110; 210); a shutter (16; 116; 1.216, 2.216) configured for cooperating the seat (14; 114; 1.214, 2.214); a pressure sensing assembly (18; 118; 1.218, 2.218) defining an internal volume (18.1; 118.1; 1.218.1, 2.218.1) filled with an auxiliary gas and closed by a plug (24; 124; 1.224, 2.224; 324.1, 324.2), said pressure sensing assembly being elastically deformable and located in the gas passage downstream of the seat (14; 114; 1.214, 2.214), said pressure sensing assembly being configured for actuating the shutter (16; 116; 1.216, 2.216) relative to the seat (14; 114; 1.214, 2.214) depending on a gas pressure downstream of the seat; characterized in that the pressure regulator (2; 102; 202) further comprises: a port (20; 120; 1.220, 2.220; 320) fluidly connected, via the plug (24; 124; 1.224, 2.224; 324.1, 324.2), to the internal volume (18.1; 118.1; 1.218.1, 2.218.1) of the pressure sensing assembly (18; 118; 1.218, 2.218), and configured for fluidly connecting an external source of the auxiliary gas to said internal volume (18.1; 118.1; 1.218.1, 2.218.1) for adjusting a pressure of the auxiliary gas in said internal volume.