15°C - The Ultimate App for Calculating Gas Bottle Pressure at 15°C Looking for a solution to calculate gas bottle pressure at 15°C? With the "15°C" app, you can easily input the current pressure and temperature of your gas bottle and get accurate results instantly. "15°C" calculates the pressure using the current temperatures and pressures of your gas bottle to provide reliable results. Supported Gases "15°C" supports the calculation of oxygen (O2), argon (Ar), nitrogen (N2), air, hydrogen (H2), helium (He), and CO2 mixtures.