What does a CGI measure?

A CGI, or Combustible Gas Indicator, is a device designed to detect and measure the concentration of flammable vapors in the atmosphere. This equipment is essential for ensuring safety in environments where there may be a risk of explosive gases, such as at sites with underground storage tanks. By monitoring levels of combustible gases, a CGI helps prevent hazardous situations that could arise from accumulating vapors, making it a vital tool for site assessments and safety measures.

The other choices do not accurately describe the function of a CGI; they pertain to measurements that are unrelated to the detection of flammable vapors. For example, measuring oxygen concentration or temperature is not the focus of a CGI, nor does it measure pressure inside storage tanks. The primary purpose of a CGI is to ensure that any flammable gases are identified promptly, allowing for appropriate safety protocols to be implemented.