# Calculations help

1. May 16, 2012

### Scara

Hi Folks,

Not the best at this so hoping somebidy can help me.

I have a 67.4 litre vessel and I'm filling it with SF6 to 6Bar. Can I work out how much SF6 I'm using in litres?

Is this a dumb question? should nI be asking what weight I'm using.

I've been asked to supply usage in litres.

2. May 16, 2012

### Q_Goest

Hi Scara. I can give you the density of SF6 if you can provide the temperature and verify the pressure is gage and not absolute pressure.

3. May 16, 2012

### Scara

The sf 6 is at room temperature around 20deg Celsius . Pressure measured on vessel with gage.

4. May 16, 2012

### Q_Goest

At 6 barg and 20 C, density is roughly 46.5 kg/m3. The saturation temperature at this pressure is -19 C and at atmospheric pressure the saturation temperature is -68 C.

So at this pressure and temperature, you have a superheated gas. I'm not sure why or how you could put that into liters, but I wonder if there is a liquid source and you're being asked to determine how many liquid liters are needed for this 64.7 L vessel, in which case you need to define the conditions of the liquid source.