Which refrigerant is known by its chemical designation R717?

• A. R22
• B. R12
• C. Ammonia
• D. R502

Answer: (C)

The refrigerant known by its chemical designation R717 is ammonia. Ammonia has been used as a refrigerant for over a century and is recognized for its efficiency and low environmental impact compared to many synthetic refrigerants. It has a high thermal conductivity and is often used in industrial refrigeration applications.

Ammonia's characteristic properties include being a natural refrigerant with a zero ozone depletion potential (ODP), making it an eco-friendly choice in comparison to some halocarbon refrigerants. Additionally, ammonia is a toxic substance, and appropriate safety measures must be taken when handling it, which is well documented in industry practices.

In the context of the other options provided, R22, R12, and R502 are all synthetic refrigerants and are not equivalent to ammonia. Specifically, R22 and R12 are both chlorofluorocarbons (CFCs) or hydrochlorofluorocarbons (HCFCs) with higher ozone depletion potentials, while R502 is a blend of R22 and R115. None of these options carry the designation R717, which is specifically assigned to ammonia.