# I Percentage of gas in tank

1. Sep 10, 2016

### Graaf van Vlaanderen

We discovered a leak in a SF6 gas HV circuit breaker. Since we don't know when the leak occurred due to temperature changes I assume there is only air left in the tank.
Here is my question. Suppose I have a tank with a fixed volume filled with air at the same pressure as the atmospheric pressure. When we add SF6 gas up to 0.2bar over pressure, what would then be the percentage of each gas (air and SF6) in the tank?

2. Sep 10, 2016

### Bystander

You have three numbers; what do you calculate from them?

3. Sep 10, 2016

### Graaf van Vlaanderen

Well, I consider T and V constant, hence ntot = n(air) + n(SF6) => ptot = p(atm) + p(SF6)
Hence %SF6 = (0.2/1.2)*100. Not sure this is correct.

4. Sep 10, 2016

### Bystander

You got it.

5. Sep 14, 2016

### Khashishi

But I'd expect all the SF6 will pool on the bottom of the tank.