CFESA Gas Equipment and Safety 4 — Questions and Answers
Question 1: A commercial fryer is producing a lazy, yellow-orange flame. What is the most likely cause?
- Insufficient air supply to the burner (Correct answer)
- Excessive gas pressure at the manifold
- A cracked heat exchanger
- A faulty thermocouple
Correct answer: Insufficient air supply to the burner
A yellow or orange lazy flame indicates incomplete combustion due to insufficient primary air reaching the burner.
Question 2: When performing a gas leak test on a newly installed commercial range, which substance is approved for use on gas connections?
- Soap and water solution
- An electronic leak detector only
- Listed leak detection solution or electronic detector (Correct answer)
- Compressed air
Correct answer: Listed leak detection solution or electronic detector
NFPA 54 and manufacturer guidelines permit the use of listed leak detection solution or an approved electronic detector to check connections.
Question 3: What is the function of a redundant safety valve (RSV) on a commercial gas appliance?
- It regulates gas pressure to the burner orifice
- It provides two independent gas shutoff seats in series for added safety (Correct answer)
- It controls pilot flame sensing
- It bypasses the pressure regulator during ignition
Correct answer: It provides two independent gas shutoff seats in series for added safety
A redundant safety valve contains two independent operator seats in series so that if one fails, the second prevents gas flow.
Question 4: A technician measures manifold pressure on a natural gas appliance and reads 4.5 inches W.C. The rated manifold pressure is 3.5 inches W.C. What should the technician do?
- Adjust the primary air shutter to compensate
- Adjust the supply regulator to lower pressure to 3.5 inches W.C. (Correct answer)
- Replace the burner orifice with a smaller size
- Notify the gas utility and take no further action
Correct answer: Adjust the supply regulator to lower pressure to 3.5 inches W.C.
Manifold pressure above the rated value must be corrected by adjusting the appliance or supply regulator to the manufacturer's specification.
Question 5: Which condition would cause a pilot flame to fail to heat the thermocouple sufficiently?
- Pilot orifice is partially blocked reducing flame size (Correct answer)
- Gas supply pressure is 0.5 inches W.C. above rating
- The thermostat is set too low
- The main burner orifice is oversized
Correct answer: Pilot orifice is partially blocked reducing flame size
A blocked pilot orifice reduces the pilot flame so it does not fully engulf the thermocouple tip, resulting in insufficient millivolt output.
Question 6: Under NFPA 96, what minimum clearance is required between a commercial cooking appliance and combustible material on the sides?
- 6 inches
- 12 inches
- 18 inches
- Clearances are determined by manufacturer's installation instructions (Correct answer)
Correct answer: Clearances are determined by manufacturer's installation instructions
NFPA 96 requires that installation clearances from combustible construction follow the manufacturer's installation instructions as the governing document.
Question 7: A standing pilot on a commercial broiler repeatedly goes out during operation. After verifying gas pressure and pilot orifice are correct, what is the next most likely cause?
- Thermocouple probe is positioned outside the pilot flame cone (Correct answer)
- The gas valve operator coil has shorted
- Manifold pressure is too high
- The burner orifice requires cleaning
Correct answer: Thermocouple probe is positioned outside the pilot flame cone
If the thermocouple tip is not fully engulfed by the pilot flame, it cannot generate sufficient millivoltage to hold the safety valve open.
CFESA Gas Equipment and Safety 4
A commercial fryer is producing a lazy, yellow-orange flame.
What is the most likely cause?