G2 Gas Fitter Practice Exam

What principle does a filament CGI unit operate on?

1. Electrical resistance

2. Radiant heating

3. Catalytic combustion

4. Convection

The correct answer is: Catalytic combustion

A filament CGI unit operates on the principle of catalytic combustion. This process involves the use of a catalyst to facilitate a chemical reaction at lower temperatures than would normally be required for combustion to take place. In a filament CGI unit, gas is passed over a catalytic element, which promotes the oxidation of the gas, resulting in the generation of heat without the creation of a flame. Catalytic combustion is advantageous in several ways. It is generally more efficient and produces lower emissions compared to traditional combustion methods. By utilizing a catalyst, the reaction can occur more smoothly and quickly, ensuring that a greater percentage of the fuel is converted into usable energy. This makes catalytic systems an environmentally friendly option. The other principles mentioned, such as electrical resistance, radiant heating, and convection, do not accurately describe how a filament CGI unit works. Electrical resistance relates to the conversion of electrical energy into heat, which is not the mechanism utilized in this context. Radiant heating involves the transfer of heat through infrared radiation, while convection refers to heat transfer through the movement of fluids. None of these principles apply directly to the catalytic combustion process employed by a filament CGI unit.