G3 Properties of Fuel Gases 3

Question 1

What happens to natural gas volume when temperature increases at constant pressure?

Accepted Answer

Volume increases proportionally (Charles's Law)

Answer

Charles's Law: volume increases proportionally with temperature at constant pressure.

Question 2

Why does natural gas heating value vary between supply regions?

Accepted Answer

Composition varies by source with different hydrocarbon proportions

Answer

Different geological sources produce gas with varying methane, ethane, and propane proportions.

Question 3

What is flame rectification in gas appliances?

Accepted Answer

Proving flame presence by detecting electrical conductivity of a flame

Answer

A flame rod conducts AC current that becomes rectified (DC) by the flame to confirm ignition.

Question 4

How does propane's flue gas dew point compare to natural gas?

Accepted Answer

Propane has a higher dew point (~59°C) than natural gas (~54°C)

Answer

Propane produces more water vapour per BTU, giving a higher dew point of about 59°C.

Question 5

How does altitude affect gas appliance performance?

Accepted Answer

Higher altitude means less oxygen, requiring derating

Answer

At higher altitudes, reduced air density means less oxygen, requiring input reduction.

G3 - Gas Technician Level 3 Certification Practice Test