F60 Gas Cylinder Storage and Handling 2 — Questions and Answers
Question 1: Before attaching a regulator to a compressed gas cylinder, what brief preparatory action should be performed with the cylinder valve?
- Apply Teflon tape to the valve threads
- Open the valve fully and leave it open
- 'Crack' the valve momentarily to clear any debris (Correct answer)
- Heat the valve with a torch to loosen it
Correct answer: 'Crack' the valve momentarily to clear any debris
'Cracking' the valve briefly expels dust and debris from the outlet that could contaminate the regulator or become an ignition hazard.
Question 2: Which fuel gas commonly used in torch operations is lighter than air and rises when it leaks?
- Propane
- Butane
- Acetylene (Correct answer)
- Liquefied petroleum gas (LPG)
Correct answer: Acetylene
Acetylene has a specific gravity of approximately 0.9, making it lighter than air, so it rises and disperses upward when released.
Question 3: To prevent dangerous decomposition, acetylene must not be used at pressures exceeding what limit?
- 5 psi
- 10 psi
- 15 psi (Correct answer)
- 25 psi
Correct answer: 15 psi
Acetylene can spontaneously and violently decompose when used at pressures above 15 psi, creating a severe explosion risk.
Question 4: When propane leaks in an enclosed space, where does the greatest risk of accumulation occur?
- Near the ceiling where ventilation is poorest
- At floor level, since propane is heavier than air (Correct answer)
- At mid-room height where it remains suspended
- Near windows where air currents concentrate it
Correct answer: At floor level, since propane is heavier than air
Propane has a specific gravity of about 1.5, so it sinks and accumulates at floor level, where it can reach explosive concentrations.
Question 5: What is the correct and safe method for checking torch equipment connections for gas leaks?
- Hold a lit match near the connection to detect escaping gas
- Apply soapy water and watch for bubbles (Correct answer)
- Smell each connection directly for gas odor
- Apply pipe joint compound and observe for cracks
Correct answer: Apply soapy water and watch for bubbles
Soapy water produces visible bubbles at leaking connections, providing a safe and reliable detection method without introducing any ignition source.
Question 6: What is the correct sequence for shutting down torch equipment at the end of a work period?
- Close torch fuel valve, then torch oxygen valve, then cylinder valves
- Close cylinder valves first, bleed gas from lines through the torch, then close torch valves (Correct answer)
- Turn all valves off simultaneously to save time
- Close only the oxygen cylinder valve, leaving fuel available for re-ignition
Correct answer: Close cylinder valves first, bleed gas from lines through the torch, then close torch valves
Closing cylinder valves first and bleeding lines through the torch ensures no pressurized gas remains trapped in hoses and regulators, preventing hose burnback.
Question 7: During torch operations, what minimum clearance must be maintained between the torch flame and combustible materials?
- 2 feet
- 4 feet
- 6 feet (Correct answer)
- 10 feet
Correct answer: 6 feet
A minimum 6-foot clearance from combustible materials is required during torch operations to prevent accidental ignition of nearby materials.
F60 Gas Cylinder Storage and Handling 2
Before attaching a regulator to a compressed gas cylinder, what brief preparatory action should be performed with the cylinder valve?