What is TW required for when calculating cylinder filling?

The correct answer is based on the importance of weight when calculating cylinder filling for LP-gas. The term "TW" refers to the "tare weight," which is the weight of the empty LP-gas cylinder itself. When filling a cylinder, it is essential to know this weight to accurately determine how much gas is being added.

To avoid overfilling, which can lead to hazardous situations, the amount of LP-gas loaded into the cylinder is calculated by subtracting the tare weight from the gross weight after filling. This ensures that the cylinder does not exceed its safe filling capacity, which is critical for safety and compliance with regulations.

The other factors listed, such as volume, length, and pressure, do not directly pertain to the fundamental metric required to safeguard against overfilling. While they might be relevant in broader contexts of handling LP-gas, they do not serve the specific need of tracking the weight of contents in the cylinder during the filling process.