Suppressant detection based on capacitive sensing

1. A fire suppression system, comprising:

a cylinder having a wall defining an inner chamber;

a siphon tube disposed within the inner chamber and spaced apart from the wall;

the siphon tube comprises opposing first and second ends, the first end coupled to an output of the cylinder, the second end proximate to a base portion of the wall, the cylinder including a gap between the second end and the base portion; and

a processor operable to determine an amount of a suppressant in the inner chamber based on a capacitance between a first electrode and a second electrode that are both in contact with the suppressant;

wherein:

one of the first and second electrodes includes the siphon tube, and the other of the first and second electrodes includes the wall;

each of the first electrode and second electrode is also in contact with a pressurant in the inner chamber;

the capacitance is an effective capacitance based on a first capacitance between the first and second electrodes with the suppressant as a dielectric medium, and a second capacitance between the first and second electrodes with the pressurant as a dielectric medium; and

the effective capacitance is also based on a stray capacitance of each of the siphon tube and the wall, and the stray capacitance is indicative of a size of the gap.

2. The fire suppression system of claim 1 , wherein the siphon tube and cylinder are concentric.

3. The fire suppression system of claim 1 , wherein the determination of the amount of suppressant in the inner chamber is based on:

a radius of the siphon tube;

a radius of the cylinder;

a dielectric constant of the suppressant;

a dielectric constant of the pressurant; and

a size of the gap between the base portion of the cylinder and the second end of the siphon tube.

4. The fire suppression system of claim 1 , wherein the processor is operable to determine the amount of suppressant in the inner chamber based on a predefined mapping between capacitance values and suppressant amounts for the cylinder.

5. The fire suppression system of claim 1 , comprising:

an electronic display, the processor operable to display an indication of the amount of suppressant on the electronic display.

6. The fire suppression system of claim 1 , comprising:

a measuring circuit operable to measure the capacitance between the first and second electrodes and provide the measured capacitance to the processor.

7. A method for determining an amount of suppressant in a cylinder, comprising:

measuring a capacitance between a first electrode and a second electrode that are both in contact with a suppressant within a cylinder; and

a determining an amount of suppressant within the cylinder based on the capacitance;

wherein:

each of the first electrode and second electrode is also in contact with a pressurant within the cylinder;

the capacitance is an effective capacitance based on a first capacitance between the first and second electrodes with the suppressant as a dielectric medium, and a second capacitance between the first and second electrodes with the pressurant as a dielectric medium; and

said measuring a capacitance between a first electrode and a second electrode comprises utilizing a wall of the cylinder as one of the first and second electrodes, and utilizing a siphon tube disposed within the cylinder as the other of the first and second electrodes; and

said determining an amount of suppressant within the cylinder is based on each of the following:

a radius of the siphon tube;

a radius of the cylinder;

a dielectric constant of the suppressant;

a dielectric constant of the pressurant; and

a size of a gap between a base portion of the cylinder and an end of the siphon tube.

8. The method of claim 7 , wherein the effective capacitance is also based on a stray capacitance of each of the first and second electrodes.

9. The method of claim 7 , wherein said measuring a capacitance between a first electrode and a second electrode comprises utilizing a wall of the cylinder as one of the first and second electrodes, and utilizing a siphon tube disposed within the cylinder as the other of the first and second electrodes.

10. The method of claim 7 , wherein said a determining an amount of the suppressant within the cylinder based on the capacitance is performed using a predefined mapping between capacitance values and suppressant amounts for the cylinder.