G3 G3 - Gas Technician Level 3 Pressure Regulation and Control Questions and Answers 1 — Questions and Answers
Question 1: What is the primary function of a gas pressure regulator?
- To increase gas pressure for high-BTU appliances
- To reduce and maintain a constant downstream gas pressure regardless of upstream fluctuations (Correct answer)
- To measure gas consumption
- To filter debris from the gas supply
Correct answer: To reduce and maintain a constant downstream gas pressure regardless of upstream fluctuations
A pressure regulator automatically reduces inlet pressure to a stable, lower outlet pressure suitable for appliances.
Question 2: In a two-stage gas distribution system, the first-stage regulator typically reduces line pressure from high pressure to approximately:
- 0.25 in. W.C.
- 2 psi (medium pressure) (Correct answer)
- 60 psi
- 7 in. W.C.
Correct answer: 2 psi (medium pressure)
First-stage regulators in two-stage systems reduce high-pressure distribution gas to an intermediate medium pressure of around 2 psi for delivery to homes or buildings.
Question 3: The outlet pressure for most residential gas appliances in the US served by natural gas is typically:
- 2 psi
- 3.5 in. W.C. (approximately 0.87 kPa) (Correct answer)
- 14 in. W.C.
- 60 psi
Correct answer: 3.5 in. W.C. (approximately 0.87 kPa)
Most residential natural gas appliances are designed to operate at 3.5 in. W.C. (about 0.125 psi) outlet pressure.
Question 4: A pressure regulator that allows outlet pressure to rise above its set point when gas flow stops is said to exhibit:
- Lock-up
- Droop
- Creep (Correct answer)
- Surge
Correct answer: Creep
Creep (also called lock-up pressure rise) occurs when a regulator allows pressure to drift upward above set-point at zero flow due to a worn or improperly seated valve.
Question 5: What is 'droop' in the context of a gas pressure regulator?
- Physical sagging of the regulator body
- The decrease in outlet pressure that occurs as gas flow demand increases (Correct answer)
- An increase in outlet pressure at high flow
- A regulator vent blockage condition
Correct answer: The decrease in outlet pressure that occurs as gas flow demand increases
Droop is the reduction in regulated outlet pressure as flow through the regulator increases, a normal characteristic of spring-loaded regulators.
Question 6: A regulator vent must be positioned so that:
- It faces upward to collect rainwater
- It is protected from weather and insects while allowing free discharge of gas (Correct answer)
- It is sealed completely to prevent gas escape
- It faces the appliance it serves
Correct answer: It is protected from weather and insects while allowing free discharge of gas
Regulator vents must be protected from rain, snow, and insect intrusion while remaining open to vent diaphragm side pressure and prevent over-pressure.
G3 G3 - Gas Technician Level 3 Pressure Regulation and Control Questions and Answers 1
What is the primary function of a gas pressure regulator?