CBET Medical Gas Systems 5 — Questions and Answers
Question 1: A hospital's master alarm panel shows a 'Source Valve Closed' alarm for the surgical vacuum system. What is the FIRST corrective action?
- Shut down all surgical suites
- Locate and open the source shutoff valve (Correct answer)
- Bypass the alarm and notify engineering in 24 hours
- Replace the vacuum pump immediately
Correct answer: Locate and open the source shutoff valve
The first corrective action is to locate and open the closed source shutoff valve to restore vacuum service, then investigate the cause of the unexpected closure.
Question 2: What minimum purity level is required for medical-grade oxygen supplied by bulk cryogenic systems in the US?
- 93%
- 95%
- 99% (Correct answer)
- 99.5%
Correct answer: 99%
USP medical oxygen requires a minimum purity of 99.0% oxygen by volume when supplied from bulk cryogenic or cylinder sources.
Question 3: Which type of medical gas outlet connector system uses non-interchangeable, gas-specific body configurations to prevent misconnections?
- DISS (Diameter Index Safety System)
- CGA pin-index system
- NIST (Non-Interchangeable Screw Thread) system
- Both DISS and NIST (Correct answer)
Correct answer: Both DISS and NIST
Both DISS and NIST systems use gas-specific, non-interchangeable connector geometries for wall outlets and low-pressure hose connections to prevent misconnections.
Question 4: During routine PM on a medical gas manifold, a technician finds a pressure gauge reading 10% lower than the adjacent calibrated reference gauge. What is the appropriate action?
- Recalibrate or replace the gauge and document the finding (Correct answer)
- Adjust the regulator set point to compensate
- Ignore if within 15% of reference value
- Increase supply cylinder pressure
Correct answer: Recalibrate or replace the gauge and document the finding
A gauge reading 10% low should be recalibrated or replaced per NFPA 99 maintenance requirements, and the discrepancy documented for corrective action tracking.
Question 5: What is the purpose of a pressure/vacuum indicator (PVI) installed in a medical gas zone?
- Control flow rate to patient equipment
- Provide local visual indication of line pressure without requiring tools (Correct answer)
- Automatically shut off gas if pressure drops below set point
- Filter particulate from the gas line
Correct answer: Provide local visual indication of line pressure without requiring tools
A PVI (also called a pressure indicator) provides a local visual readout of zone line pressure so clinical staff can quickly assess system status without test equipment.
Question 6: Which regulatory body classifies medical gas systems components as medical devices subject to 510(k) or PMA review?
- OSHA
- EPA
- FDA (Correct answer)
- CMS
Correct answer: FDA
The FDA classifies medical gas equipment (regulators, flowmeters, outlets) as medical devices and requires 510(k) clearance or PMA approval before marketing.
Question 7: A technician notices ice formation on the exterior of a liquid oxygen supply line during normal operation. What does this most likely indicate?
- A dangerous pressure surge in the line
- Normal condensation and freezing due to cryogenic temperatures (Correct answer)
- A significant leak of liquid oxygen
- Contamination of the oxygen with water vapor
Correct answer: Normal condensation and freezing due to cryogenic temperatures
Ice forming on liquid oxygen lines is expected because LOX at −183°C causes atmospheric moisture to condense and freeze on uninsulated pipe surfaces.
CBET Medical Gas Systems 5
A hospital's master alarm panel shows a 'Source Valve Closed' alarm for the surgical vacuum system.
What is the FIRST corrective action?