What type of equipment must be pressure tested according to the Mechanical Code?

The correct answer focuses on nonfactory-tested equipment, which is required to undergo pressure testing according to the Mechanical Code. This requirement is in place to ensure the safety and reliability of such equipment that may not have gone through rigorous testing in a factory setting. Nonfactory-tested equipment might include components that are assembled on-site or custom-built installations that haven't been subjected to the same quality controls as mass-produced items.

Pressure testing serves as a critical step in identifying leaks and ensuring that all connections and fittings can handle the pressures they will experience during operation. This is particularly vital for systems involving refrigerants or other pressurized substances, as undetected flaws can lead to inefficiencies, safety hazards, or unintentional environmental damage.

In contrast, factory-tested equipment typically already meets established standards and has undergone necessary testing to prevent issues related to pressure and leaks, thus making additional testing redundant. Standard appliances and portable refrigeration units might have specific guidelines that differ, but the emphasis on the need for pressure testing is most pertinent for nonfactory-tested equipment, reinforcing the importance of precautionary measures within mechanical installations.