Pressure regulator for gas cylinder with a low-pressure sensor and restriction for determining a gas flow and remaining usage time
A pressure regulator for a gas cylinder, comprising a gas inlet, a gas outlet and a gas passage fluidly connecting the gas inlet with the gas outlet; a pressure reducer located in the gas passage, downstream of the gas inlet; a flow selector located in the gas passage, downstream of the pressure reducer; a pressure sensor located in the gas passage between the flow selector and the gas outlet; and a flow restriction located in the gas passage and downstream of the pressure sensor.
1 . A pressure regulator for a gas cylinder, said pressure regulator comprising:
a gas inlet, a gas outlet and a gas passage fluidly connecting the gas inlet with the gas outlet;
a pressure reducer located in the gas passage, downstream of the gas inlet;
a flow selector located in the gas passage, downstream of the pressure reducer;
a pressure sensor located in the gas passage between the flow selector and the gas outlet; and
a flow restriction located in the gas passage and downstream of the pressure sensor.
2 . The pressure regulator according to claim 1 , wherein the flow selector comprises a cross-section that is selectable between a minimum cross-section and a maximum cross-section, the flow restriction having a cross-section smaller than the maximum cross-section.
3 . The pressure regulator according to claim 1 , wherein the flow restriction comprises a calibrated hole mounted upstream of the gas outlet.
4 . The pressure regulator according to claim 1 , wherein the gas passage between the flow selector and the flow restriction forms a volume of at least 1 mm 3 .
5 . The pressure regulator according to claim 1 , wherein the flow selector is configured to provide a selectable flow comprised between 0.1 and 25 litres/min.
6 . The pressure regulator according to claim 1 , wherein the flow selector provides a selectable flow in a step-wise manner only.
7 . The pressure regulator according to claim 1 further comprising a control unit to which the pressure sensor is connected and configured to determine a gas flow rate from a signal of the pressure sensor.
8 . The pressure regulator according to claim 7 , wherein the control unit is configured to determine the gas flow rate from the signal of the pressure sensor in the absence of a signal of detection of a position of the flow regulator.
9 . The pressure regulator according to claim 7 , wherein the control unit is configured to determine the gas flow rate from the signal of the pressure sensor in the absence of a signal of a direct measurement of the gas flow rate.
10 . The pressure regulator according to claim 7 further comprising a pressure switch located in the gas passage between the pressure reducer and the flow selector, and electrically connected to the control unit, the control unit being configured to switch from a sleep-mode to a wake-up mode when the gas in contact with the pressure switch reaches a pressure of at least 0.5 bar.
11 . The pressure regulator according to claim 7 further comprising a high-pressure sensor located in the gas passage upstream of the pressure reducer, and electrically connected to the control unit.
12 . The pressure regulator according to claim 11 , wherein the control unit is configured to determine a remaining usage time of the gas cylinder based on the determined gas flow and a signal of the high-pressure sensor.
13 . The pressure regulator according to claim 1 further comprising a branch of the gas passage directly connecting between the pressure reducer and the flow selector and connecting to an auxiliary connector.
14 . The pressure regulator according to claim 13 , wherein the auxiliary connector comprises a shutter that is normally closed by a spring and the pressure regulator further comprises a position sensor of the shutter.
15 . The pressure regulator according to claim 14 , wherein the auxiliary connector further comprises a position pin with that is attached to the shutter and extends away from the shutter to the position sensor for interacting with the position sensor.
16 . The pressure regulator according to claim 13 further comprising a control unit to which the pressure sensor is connected and configured to determine a gas flow rate from a signal of the pressure sensor, and a pressure switch located in the branch of the gas passage between the pressure reducer and the flow selector, and electrically connected to the control unit.
17 . The pressure regulator according to claim 1 , wherein the pressure regulator is void of a detector of a position of the flow selector and void of a gas flow sensor.
18 . A method of determining a gas flow rate at a gas outlet of a pressure regulator on a gas cylinder, wherein the pressure regulator comprises a pressure reducer and a flow selector downstream of the pressure reducer, said method comprising:
measuring a gas pressure in the gas flow downstream of the flow selector and upstream of a flow restriction; and
determining the gas flow rate based on the measured gas pressure in the gas flow downstream of the flow selector and upstream of a flow restriction.
19 . The method according to claim 18 further comprising:
measuring a pressure of the gas in the gas cylinder; and
determining a remaining usage time based on the measured pressure of the gas in the gas cylinder and the determined gas flow rate.
20 . The method according to claim 18 further comprising:
determining that the gas outlet is obstructed when the measured gas pressure in the gas flow downstream of the flow selector and upstream of a flow restriction reaches or exceeds a predetermined level, wherein the predetermined level is higher than a gas pressure in the gas flow downstream of the flow selector and upstream of a flow restriction when the flow selector is set at a maximum cross-section and in the absence of obstruction, and equal to or less than a nominal outlet pressure of the pressure reducer.