Question

The usual cooking gas (mostly methane) cylinder is about 25 cm in diameter and 80 cm in height. It is changed to 12 MPa at room temperature (27°C).

(a) Assuming the ideal gas law, find the mass of gas filled in the cylinder.

(b) Explain how the actual cylinder contains nearly 15 kg of gas.

(c) If the cylinder is to be protected against excessive pressure by means of a fusible plug, at what temperature should the plug melt to limit the maximum pressure to 15 MPa?

Answer 1

Given diameter (D) = 25 cm = 0.25 m

Height (H) = 80 cm = 0.8 m

∴ Volume of the cylinder (V) = \(\frac{πD^2}4 \times H\)

= 0.03927 m³

Gas pressure (p) = 12 MPa = 12000 kPa

Temperature (T) = 27º C = 300 K 

(a) Mass of gas filled in the cylinder

(b) In cooking gas main component is ethen and it filled in 18 bar pressure. At that pressure it is not a gas it is liquid form in atmospheric temperature so its weight is amount 14 kg.

(c) Let temperature be T K, then pressure, p = 15 MPa = 15000 kPa