What is the refrigerant number for Butane?

Butane is classified under the refrigerant designation R-600. This designation is part of a larger system used to identify various refrigerants by their chemical composition. R-600, or isobutane, is a hydrocarbon refrigerant that is commonly used in refrigeration and air conditioning applications due to its favorable thermodynamic properties and low environmental impact.

In contrast, the other options represent different refrigerants with distinct chemical compositions and applications. For example, R-290 is propane, R-404A is a blend of refrigerants used primarily in commercial refrigeration, and R-134A is a fluorocarbon refrigerant commonly used in automotive air conditioning. Each refrigerant has specific uses and characteristics that make them suitable for particular applications, further highlighting the uniqueness of R-600 as the proper identification for Butane.