Gas Fitter Practice Test

What diameter and length of a dirt pocket is required when a drop line is 3-inch diameter?

1. 3 inch diameter by 3 inches long

2. 1 inch diameter by 3 inches long

3. 3/4 inch diameter by 3 inches long

4. 2 inch diameter by 3 inches long

The correct answer is: 2 inch diameter by 3 inches long

When dealing with a drop line that has a diameter of 3 inches, the dirt pocket's diameter typically needs to accommodate the flow of gas while allowing for proper maintenance and cleaning. The requirement for a dirt pocket generally involves having a diameter that is close to, but not necessarily equal to, that of the drop line to ensure effective operation. In this case, a dirt pocket that has a diameter of 2 inches provides sufficient space around the drop line, preventing any blockage and facilitating the settling of any dirt or sediment that might accumulate. The length of 3 inches is also adequate to allow for enough capacity to collect debris without compromising the function of the drop line. This is consistent with standard practices within gas fitting, which aim to balance safety and functionality in gas delivery systems. The other choices either provide insufficient diameter or fail to align with the necessary specifications for effective dirt pocket function alongside a 3-inch diameter drop line.