North Carolina Home Inspector Practice Exam

What is the most commonly used size for a fill pipe in underground tanks?

1. 1" - 1 1/4"

2. 1 1/2" - 1 3/4"

3. 2" - 2 1/4"

4. 3" - 3 1/4"

The correct answer is: 2" - 2 1/4"

The most commonly used size for a fill pipe in underground tanks is typically in the range of 2" to 2 1/4". This size is chosen because it effectively accommodates the volume and flow of liquids being transferred into the tank while also ensuring safety and compliance with industry standards. A fill pipe of this diameter allows for rapid filling, which is essential for operational efficiency. Smaller pipes, such as those measuring 1" to 1 1/4" or 1 1/2" to 1 3/4", may not facilitate the necessary flow rates required during filling operations, leading to potential overflows or increases in pressure. Conversely, while larger sizes such as 3" to 3 1/4" might theoretically allow for even faster filling, they could introduce complications related to the tank's structure and potential for leaks at connection points. Thus, the 2" to 2 1/4" size balances effective flow rates with structural integrity and safety concerns.