What pressure should the leak test be equal to at minimum?

The correct answer reflects the standard practice in conducting a leak test, which requires that the pressure be equal to the normal service pressure of the system. This ensures that the test accurately simulates the conditions under which the system will operate, allowing for the identification of any potential leaks effectively.

Testing at normal service pressure is essential, as it provides an accurate representation of the system's performance during regular use. When a leak is present, it will typically manifest under operational pressure levels, making it crucial to test at this pressure for reliable results.

Other options might not provide the same level of assurance regarding the integrity of the system. For instance, testing at atmospheric pressure would not reveal leaks that only occur at higher pressures. Similarly, testing at the maximum pressure of the system could lead to unnecessary risks, as it might exceed safe operating conditions or compromise the integrity of the system. Lastly, any pressure above ground level lacks specificity and would not guarantee that the conditions reflect those during actual operation. Thus, testing at the normal service pressure stands as the best practice for ensuring safety and reliability in the operation of the CNG delivery system.