Which of the following criteria is not required when sizing a closed-type expansion tank?

• A. Maximum operating pressure
• B. Minimum operating pressure
• C. Temperature rating
• D. Volume capacity

Answer: (B)

When sizing a closed-type expansion tank, understanding the parameters that directly impact its functionality is crucial. One key criterion that is essential is the maximum operating pressure, as this determines the tank's ability to withstand the pressure of the system without failure. The temperature rating is also important because it ensures that the tank can handle the heat of the fluid circulating through it without degrading or losing performance. Volume capacity is critical too, as it ensures that the tank can absorb the system's thermal expansion without leading to pressure build-up.

While minimum operating pressure might seem relevant since it relates to the tank's functioning pressure range, it is not a critical parameter for sizing a closed-type expansion tank. The primary focus tends to be on the maximum operating pressure, temperature, and volume, which directly influence the tank's design and efficiency in managing thermal expansion. Therefore, minimum operating pressure is not a necessary criterion in the sizing process.