Which statement regarding ASHRAE standard classification of refrigerants is false?

The correct choice indicates that R717, which is ammonia, does not belong to the B2 classification of refrigerants. In fact, R717 is classified under group B1 according to ASHRAE standards. This classification identifies refrigerants based on their toxicity and flammability. Group B typically includes refrigerants that are considered toxic, whereas group A contains refrigerants that are classified as non-toxic. In this context, R717 is more hazardous due to its toxicity, which is why it does not fit into the B2 classification, which would imply a lower level of toxicity and a different safety profile.

The other refrigerants mentioned, R22, R134a, and R410A, are all classified within the group A1 category, indicating they are non-toxic and have low flammability. Therefore, those statements correctly reflect the proper classifications according to ASHRAE standards.