CBET Medical Gas Systems 2 — Questions and Answers
Question 1: What color is the standard pipeline and cylinder coding for medical oxygen in the United States?
- Yellow
- Green (Correct answer)
- Blue
- White
Correct answer: Green
In the US, medical oxygen is color-coded green per CGA standards.
US CGA color coding: Oxygen=Green, Air=Yellow, Nitrogen=Black, Nitrous Oxide=Blue. ISO uses White for oxygen. DISS and PISS provide mechanical keying against cross-connection.
Question 2: What is the purpose of a zone valve in a medical gas pipeline system?
- To regulate gas pressure at each outlet
- To allow isolation of gas supply to a specific area for maintenance or emergencies without affecting the entire facility (Correct answer)
- To mix gases to the correct concentration
- To filter contaminants from the gas supply
Correct answer: To allow isolation of gas supply to a specific area for maintenance or emergencies without affecting the entire facility
Zone valves allow specific sections to be shut off without interrupting supply to the rest of the facility.
NFPA 99 requires zone valves for each gas serving each area. Biomedical technicians must verify they operate freely, labeling is accurate, and alarm activation occurs when closed.
Question 3: What safety system prevents connecting a medical gas cylinder to the wrong yoke or regulator?
- Color coding only
- Pin Index Safety System (PISS) (Correct answer)
- The cylinder label
- The pressure gauge
Correct answer: Pin Index Safety System (PISS)
PISS uses specific pin positions on the cylinder valve that correspond to holes on the yoke, mechanically preventing wrong gas connection.
PISS can be defeated by missing pins, multiple washers, or forcing connections. Biomedical technicians must inspect pin condition and educate staff never to force connections.
Question 4: What does a medical gas alarm panel monitor and how should alarms be responded to?
- Room temperature requiring HVAC adjustment
- Pipeline pressure, reserve supply status, and system conditions, requiring immediate investigation (Correct answer)
- Individual cylinder levels for automatic reordering
- Gas purity requiring filter replacement
Correct answer: Pipeline pressure, reserve supply status, and system conditions, requiring immediate investigation
Medical gas alarm panels monitor pipeline pressures, reserve supply status, and operating conditions.
Alarm conditions include: main supply low, reserve in use, reserve low, pipeline pressure abnormal. Biomedical technicians must test alarm systems during PM by simulating alarm conditions.
Question 5: What is the standard operating pressure for medical gas pipeline systems (oxygen, air, nitrous oxide) in a US hospital?
- 15 psi
- 50 psi (Correct answer)
- 100 psi
- 200 psi
Correct answer: 50 psi
Standard medical gas pipeline operating pressure is 50 psi per NFPA 99.
Exception: Nitrogen operates at 160-200 psi for pneumatic surgical instruments. Low pressure can cause equipment malfunction; high pressure can damage equipment.
Question 6: Why must oil and grease be kept away from oxygen equipment and fittings?
- They can clog the gas outlets
- Oxygen is a powerful oxidizer and can cause spontaneous ignition of hydrocarbons under pressure (Correct answer)
- They reduce the purity of the oxygen
- They can corrode the metal fittings
Correct answer: Oxygen is a powerful oxidizer and can cause spontaneous ignition of hydrocarbons under pressure
Oxygen drastically lowers the ignition temperature of hydrocarbons, which can spontaneously ignite under high-pressure oxygen.
Never use petroleum-based lubricants or Teflon tape on oxygen equipment. Use only oxygen-compatible lubricants. Open cylinder valves slowly to prevent adiabatic heating.
CBET Medical Gas Systems 2
What color is the standard pipeline and cylinder coding for medical oxygen in the United States?