Device for regulating the pressure in a helium tank of an nmr magnet, comprising two pressure sensors

A device for regulating the pressure in a helium tank of an NMR magnet, comprising:

• a first pressure sensor for measuring a first pressure in the helium tank;
• at least one second pressure sensor for measuring a second pressure outside the helium tank;
• a control valve for adjusting an outflowing helium gas flow from the helium tank;
• and
• an electronic closed-loop control device that controls the control valve and is configured to:
• obtain first pressure values D1 measured by the first pressure sensor;
• adjust a position of the control valve depending on the measured first pressure values D1, wherein the first pressure values D1 are adjusted to a predetermined setpoint value SW;
• and
• obtain second pressure values D2 measured by the second pressure sensor,
• wherein the electronic closed-loop control device is further configured, in a normal operation for NMR measurements:
• to determine the setpoint SW depending on the first pressure values D1 and the second pressure values D2;
• and
• to change the setpoint value SW for the pressure in the helium tank in steps as soon as a difference DIF=D1−D2 between the measured first pressure value D1 and the measured second pressure value D2 reaches or exceeds predetermined threshold values, wherein the setpoint value SW is raised by one step when the difference DIF becomes less than or equal to an increase threshold value HSW, and the setpoint value SW is lowered by one step when the difference DIF becomes greater than or equal to a decrease threshold value SSW, with HSW<SSW, a value of said one step being selected from the range 5-25 mbar.

A method for regulating a pressure in a helium tank of an NMR magnet, the method comprising:

• measuring a first pressure in the helium tank by a first pressure sensor;
• measuring a second pressure outside the helium tank with at least one second pressure sensor;
• adjusting an outflowing helium gas flow from the helium tank with a control valve;
• and
• controlling the control valve with an electronic closed-loop control device that obtains first pressure values D1 measured by the first pressure sensor, and adjusts a position of the control valve depending on the measured first pressure values D1, so that the first pressure values D1 are adjusted to a predetermined setpoint value SW, and that obtains second pressure values D2 measured by the second pressure sensor, the electronic closed-loop control device, in a normal operation for NMR measurements, determining the setpoint SW depending on the measured first pressure values D1 and second pressure values D2, and changing the setpoint value SW for the pressure in the helium tank in steps as soon as a difference DIF=D1−D2 between the measured first pressure value D1 and the measured second pressure value D2 reaches or exceeds predetermined threshold values, wherein the setpoint value SW is raised by one step when the difference DIF becomes less than or equal to an increase threshold value HSW, and the setpoint value is lowered by one step when the difference DIF becomes greater than or equal to a decrease threshold value SSW, with HSW<SSW, a value of said one step being selected from the range 5-25 mbar.