What weight calculation method involves the water capacity to determine cylinder filling weight?

The correct method for calculating the filling weight of a liquefied petroleum gas (LPG) cylinder using its water capacity is based on the factor of 0.42. This factor accounts for the fact that propane and butane have specific gravities lighter than water, and this conversion allows for accurate determination of the weight of the gas contained within the cylinder.

When the water capacity of a cylinder is multiplied by 0.42, it gives the weight of the liquefied gas in pounds (or kilograms) that can safely be filled into that cylinder. This method is essential for ensuring the safe and efficient filling of LPG cylinders, as it takes into consideration the properties of the gas and ensures compliance with safety standards outlined in the NFPA 58 code. By using this calculation, one can determine the appropriate fill level, avoiding overfilling and ensuring safe operation.

The other methods listed don't align with the standard practices and could lead to inaccurate calculations, thereby compromising the safety and efficacy of the LPG cylinder filling process.