Gas Fitter Practice Test

If 1 cubic foot of natural gas is 1000 Btuh, what is the ratio of dilution air?

1. 10

2. 5

3. 15

4. 30

The correct answer is: 15

In gas combustion, dilution air refers to the air that is mixed with the fuel for the purpose of achieving efficient combustion while controlling emissions. When assessing the ratio of dilution air to fuel, you need to consider the energy content of the natural gas being burned. Given that 1 cubic foot of natural gas equates to 1000 Btuh, the dilution air ratio is derived by determining how much air is required to completely combust the natural gas efficiently. A commonly used ratio for dilution air in natural gas combustion is often in the range of 10:1 to 15:1, depending on the efficiency of the burner and the completeness of combustion desired. The ratio of 15 indicates that for every unit of natural gas, you would need approximately 15 units of air to ensure complete combustion, which aligns with standard practices for achieving optimal combustion and minimizing emissions. In this scenario, selecting the ratio of 15 reflects the need for sufficient dilution air to ensure that the combustion process operates efficiently while taking into account safety and environmental considerations. Therefore, this choice is substantiated by combustion principles that emphasize the importance of mixing the correct amount of air with the fuel for optimal performance.