What does a cylinder pressure gauge indicate?

A cylinder pressure gauge is designed to measure the pressure of the gas within the cylinder, which directly correlates to the amount of shielding gas that is present. As the gas is used during welding, the pressure decreases, indicating how much gas remains. Therefore, option B is accurate because it reflects the primary function of the gauge, which is to inform the welder about the quantity of gas available for the welding process.

The other options do not correctly describe the function of a cylinder pressure gauge. The gauge does not measure temperature (option A), nor does it assess the atmospheric pressure of the welding area (option C). Additionally, it does not provide information about contamination levels in the gas (option D). Thus, understanding that the cylinder pressure gauge is focused on the quantity of gas helps clarify its essential role in maintaining adequate shielding during the welding process.