Medical Gas Exam 2026 COMPLETE QUESTIONS
WITH CORRECT DETAILED ANSWERS
1. What is the primary standard that governs the installation and maintenance
of medical gas systems in the United States?
A) OSHA
B) NFPA 99
C) The Joint Commission
D) CMS
Answer: B) NFPA 99. This is the "Health Care Facilities Code" published by the
National Fire Protection Association. It is the foundational standard for the design,
installation, testing, and maintenance of medical gas and vacuum systems.
2. What color is the standard for medical air outlet in the United States?
A) Yellow
B) Black
C) White
D) Blue
Answer: C) White. Medical Air is designated by the color white. Oxygen is green,
Nitrous Oxide is blue, and Medical Vacuum is yellow.
3. A "DISS" connection is primarily used for:
A) High-pressure cylinder connections
B) Pipeline outlet connections
C) Station outlet and hose connections
D) Vacuum inlet connections
Answer: C) DISS stands for Diameter Index Safety System. It is a non-
interchangeable safety system for medical gas connections at the low-pressure
(pipeline) side, such as between a wall outlet and a flowmeter.
4. The purpose of a pressure relief valve on a medical gas manifold is to:
A) Control the flow to the patient
B) Protect the system from over-pressurization
,C) Act as a main system shut-off
D) Vent waste gases to the atmosphere
Answer: B) Pressure relief valves are critical safety devices that automatically
open to release pressure if it exceeds a safe limit, preventing damage to pipes and
components.
5. What is the minimum number of oxygen cylinders typically required to be
connected to a main supply manifold?
A) One
B) Two
C) Three
D) Four
Answer: B) NFPA 99 requires manifolds to have at least two banks of cylinders to
allow one bank to be the active supply while the other is a reserve, enabling
continuous supply during cylinder changeover.
6. The "Pin Index Safety System" (PISS) is designed to:
A) Prevent cross-connection of pipeline gases
B) Prevent the wrong cylinder from being connected to a yoke
C) Ensure proper flowmeter settings
D) Identify the contents of a cylinder by color
Answer: B) The Pin Index Safety System uses a specific arrangement of pins and
holes on the cylinder valve and regulator yoke to ensure that only the correct gas
cylinder can be physically attached.
7. The primary purpose of an alarm system for a medical gas supply is to:
A) Notify patients of low flow
B) Alert staff to a change in gas concentration
C) Warn of system pressure deviations
D) Signal when a cylinder is empty
Answer: C) Medical gas alarms (master, area, local) are designed to monitor
system pressure. They alert staff to potentially dangerous conditions like high
pressure (risk of barotrauma) or low pressure (loss of supply).
,8. What is the operating pressure range for a medical-surgical vacuum system at
the outlet?
A) 40-60 PSIG
B) 50-55 PSIG
C) 12-14 inHg
D) 19-21 inHg
Answer: D) Medical-surgical vacuum systems are designed to provide a pressure
of 19 to 21 inches of mercury (inHg) vacuum at the outlet.
9. A "Zone Valve" in a medical gas system is used to:
A) Control the pressure in a specific zone
B) Shut off the gas supply to a specific area for maintenance or emergency
C) Mix gases for a specific procedure
D) Act as a pressure-reducing valve
Answer: B) Zone valves, also called section valves or line valves, allow for the
isolation of a specific section (e.g., a patient room, ICU pod, or entire floor)
without affecting the rest of the system.
10. Who is authorized to perform brazing on medical gas pipeline systems?
A) Any licensed plumber
B) A certified medical gas verifier
C) A qualified installer with med gas brazer certification
D) A facility maintenance engineer
Answer: C) NFPA 99 requires that individuals who braze medical gas piping must
be specially certified through an accredited program (e.g., ASSE 6040).
11. The gas used to purge a medical oxygen line before brazing is:
A) Medical Oxygen
B) Medical Air
C) Nitrogen
D) Oil-free, dry Nitrogen
Answer: D) Oil-free, dry nitrogen is used as an inert purge gas during brazing to
prevent the formation of scale (copper oxide) inside the pipes.
, 12. What does a "WAGD" system stand for?
A) Waste Anesthesia Gas Disposal
B) Wall Air and Gas Distribution
C) Wide Area Gas Dilution
D) Waste Air and Gas Drain
Answer: A) WAGD stands for Waste Anesthesia Gas Disposal. It is a scavenging
system that removes anesthetic gases from the operating room environment to
protect healthcare workers.
13. The purpose of a "check valve" in a medical gas system is to prevent:
A) Over-pressurization
B) Pressure fluctuations
C) Backflow
D) Leaks
Answer: C) A check valve is a one-way valve that allows gas to flow in only one
direction, preventing backflow and contamination of the system.
14. A cross-connection in a medical gas system is:
A) A connection between two different gas lines
B) A connection that allows for gas mixing
C) A type of DISS fitting
D) A connection between a gas line and a vacuum line
Answer: A) A cross-connection is a dangerous misconnection where one gas
pipeline is connected to another (e.g., oxygen connected to a nitrous oxide line),
which can lead to patient injury or death.
15. The final and most critical test of a new medical gas pipeline system is
performed by:
A) The installing contractor
B) The facility's biomedical department
C) An independent, certified medical gas verifier
D) The architect of record
Answer: C) A certified medical gas verifier (ASSI 6030) is an independent third
WITH CORRECT DETAILED ANSWERS
1. What is the primary standard that governs the installation and maintenance
of medical gas systems in the United States?
A) OSHA
B) NFPA 99
C) The Joint Commission
D) CMS
Answer: B) NFPA 99. This is the "Health Care Facilities Code" published by the
National Fire Protection Association. It is the foundational standard for the design,
installation, testing, and maintenance of medical gas and vacuum systems.
2. What color is the standard for medical air outlet in the United States?
A) Yellow
B) Black
C) White
D) Blue
Answer: C) White. Medical Air is designated by the color white. Oxygen is green,
Nitrous Oxide is blue, and Medical Vacuum is yellow.
3. A "DISS" connection is primarily used for:
A) High-pressure cylinder connections
B) Pipeline outlet connections
C) Station outlet and hose connections
D) Vacuum inlet connections
Answer: C) DISS stands for Diameter Index Safety System. It is a non-
interchangeable safety system for medical gas connections at the low-pressure
(pipeline) side, such as between a wall outlet and a flowmeter.
4. The purpose of a pressure relief valve on a medical gas manifold is to:
A) Control the flow to the patient
B) Protect the system from over-pressurization
,C) Act as a main system shut-off
D) Vent waste gases to the atmosphere
Answer: B) Pressure relief valves are critical safety devices that automatically
open to release pressure if it exceeds a safe limit, preventing damage to pipes and
components.
5. What is the minimum number of oxygen cylinders typically required to be
connected to a main supply manifold?
A) One
B) Two
C) Three
D) Four
Answer: B) NFPA 99 requires manifolds to have at least two banks of cylinders to
allow one bank to be the active supply while the other is a reserve, enabling
continuous supply during cylinder changeover.
6. The "Pin Index Safety System" (PISS) is designed to:
A) Prevent cross-connection of pipeline gases
B) Prevent the wrong cylinder from being connected to a yoke
C) Ensure proper flowmeter settings
D) Identify the contents of a cylinder by color
Answer: B) The Pin Index Safety System uses a specific arrangement of pins and
holes on the cylinder valve and regulator yoke to ensure that only the correct gas
cylinder can be physically attached.
7. The primary purpose of an alarm system for a medical gas supply is to:
A) Notify patients of low flow
B) Alert staff to a change in gas concentration
C) Warn of system pressure deviations
D) Signal when a cylinder is empty
Answer: C) Medical gas alarms (master, area, local) are designed to monitor
system pressure. They alert staff to potentially dangerous conditions like high
pressure (risk of barotrauma) or low pressure (loss of supply).
,8. What is the operating pressure range for a medical-surgical vacuum system at
the outlet?
A) 40-60 PSIG
B) 50-55 PSIG
C) 12-14 inHg
D) 19-21 inHg
Answer: D) Medical-surgical vacuum systems are designed to provide a pressure
of 19 to 21 inches of mercury (inHg) vacuum at the outlet.
9. A "Zone Valve" in a medical gas system is used to:
A) Control the pressure in a specific zone
B) Shut off the gas supply to a specific area for maintenance or emergency
C) Mix gases for a specific procedure
D) Act as a pressure-reducing valve
Answer: B) Zone valves, also called section valves or line valves, allow for the
isolation of a specific section (e.g., a patient room, ICU pod, or entire floor)
without affecting the rest of the system.
10. Who is authorized to perform brazing on medical gas pipeline systems?
A) Any licensed plumber
B) A certified medical gas verifier
C) A qualified installer with med gas brazer certification
D) A facility maintenance engineer
Answer: C) NFPA 99 requires that individuals who braze medical gas piping must
be specially certified through an accredited program (e.g., ASSE 6040).
11. The gas used to purge a medical oxygen line before brazing is:
A) Medical Oxygen
B) Medical Air
C) Nitrogen
D) Oil-free, dry Nitrogen
Answer: D) Oil-free, dry nitrogen is used as an inert purge gas during brazing to
prevent the formation of scale (copper oxide) inside the pipes.
, 12. What does a "WAGD" system stand for?
A) Waste Anesthesia Gas Disposal
B) Wall Air and Gas Distribution
C) Wide Area Gas Dilution
D) Waste Air and Gas Drain
Answer: A) WAGD stands for Waste Anesthesia Gas Disposal. It is a scavenging
system that removes anesthetic gases from the operating room environment to
protect healthcare workers.
13. The purpose of a "check valve" in a medical gas system is to prevent:
A) Over-pressurization
B) Pressure fluctuations
C) Backflow
D) Leaks
Answer: C) A check valve is a one-way valve that allows gas to flow in only one
direction, preventing backflow and contamination of the system.
14. A cross-connection in a medical gas system is:
A) A connection between two different gas lines
B) A connection that allows for gas mixing
C) A type of DISS fitting
D) A connection between a gas line and a vacuum line
Answer: A) A cross-connection is a dangerous misconnection where one gas
pipeline is connected to another (e.g., oxygen connected to a nitrous oxide line),
which can lead to patient injury or death.
15. The final and most critical test of a new medical gas pipeline system is
performed by:
A) The installing contractor
B) The facility's biomedical department
C) An independent, certified medical gas verifier
D) The architect of record
Answer: C) A certified medical gas verifier (ASSI 6030) is an independent third
