HVAC - EPA Certification Practice Exam

What was the minimum vapor pressure for R-11 systems before November 15, 1993?

1. 20 inches Hg

2. 25 inches Hg

3. 30 mm Hg

4. 27 inches Hg

The correct answer is: 25 inches Hg

The minimum vapor pressure for R-11 systems before November 15, 1993, was established at 25 inches of mercury (inHg). This specific measurement is critical in ensuring proper handling and operation of refrigerants under defined conditions to prevent potential hazardous situations, such as leakage or inefficient system performance. R-11, also known as trichlorofluoromethane, was widely used in various HVAC applications, and its vapor pressure is a significant factor in its management. Vapor pressure refers to the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases (liquid or solid) at a given temperature. Maintaining the correct vapor pressure helps ensure that the refrigerant behaves as expected in the system, effectively facilitating heat exchange. Understanding this minimum vapor pressure standard is essential not only for compliance with the EPA regulations but also for the overall safety and efficiency of HVAC systems utilizing refrigerants like R-11. The specifications typically exist within the context of refrigerants' stability and environmental impact, guiding technicians in their work with these substances.