RMGA Medical Gas Systems Design & Components 3 — Questions and Answers
Question 1: What is the maximum allowable concentration of carbon monoxide (CO) in medical-grade compressed air per NFPA 99?
- 1 ppm
- 5 ppm (Correct answer)
- 10 ppm
- 25 ppm
Correct answer: 5 ppm
NFPA 99 limits carbon monoxide in medical compressed air to no more than 5 ppm to protect patients from CO toxicity.
Question 2: Which of the following piping materials is explicitly prohibited for use in medical gas distribution systems?
- Type K copper tubing
- Type L copper tubing
- Galvanized steel pipe (Correct answer)
- Type ACR copper tubing
Correct answer: Galvanized steel pipe
Galvanized steel pipe is prohibited because zinc coating can react with oxygen and other medical gases, creating contamination hazards.
Question 3: In a medical vacuum system, what is the standard design inlet pressure (vacuum level) required at patient care area outlets per NFPA 99?
- 10 in Hg minimum
- 12 in Hg minimum
- 15 in Hg minimum (Correct answer)
- 20 in Hg minimum
Correct answer: 15 in Hg minimum
Medical vacuum systems must provide a minimum of 15 inches of mercury (in Hg) vacuum at any outlet in a patient care area under full system load.
Question 4: What type of joint is required for all brazed copper medical gas piping connections per NFPA 99?
- Soldered socket joint using 50/50 tin-lead solder
- Brazed socket joint using BCuP or BAg filler metals (Correct answer)
- Threaded NPT mechanical joint
- Compression fitting with PTFE tape
Correct answer: Brazed socket joint using BCuP or BAg filler metals
All medical gas piping joints must be brazed using approved BCuP or BAg filler metals; soft solder is prohibited due to insufficient strength and melting point.
Question 5: A ceiling-mounted medical gas outlet boom in an ICU is supplied from which part of the zone distribution system?
- The main hospital header line only
- The local zone branch downstream of the zone valve box (Correct answer)
- Directly from the bulk storage source manifold
- The area alarm panel distribution board
Correct answer: The local zone branch downstream of the zone valve box
Ceiling booms and pendants receive medical gases from the zone branch line, which is controlled by the zone valve box for that care area.
Question 6: Which NFPA 99 category defines life support and critical care medical gas systems requiring the highest level of reliability?
- Category 1 (Correct answer)
- Category 2
- Category 3
- Category 4
Correct answer: Category 1
Category 1 systems under NFPA 99 are those where failure would likely cause patient death, requiring the highest redundancy and reliability standards.
Question 7: What is the purpose of the dew point requirement for medical compressed air?
- Ensure adequate oxygen content in the air supply
- Prevent moisture condensation inside the piping distribution system (Correct answer)
- Reduce bacterial growth at point-of-use outlets
- Maintain correct gas pressure throughout the system
Correct answer: Prevent moisture condensation inside the piping distribution system
A low dew point requirement ensures that moisture will not condense in the distribution piping, which would promote corrosion and microbial growth.
RMGA Medical Gas Systems Design & Components 3
What is the maximum allowable concentration of carbon monoxide (CO) in medical-grade compressed air per NFPA 99?