CHC MEP Systems in Healthcare Facilities 1 — Questions and Answers
Question 1: According to ASHRAE 170, what is the minimum number of total air changes per hour (ACH) required for an operating room?
- 6 ACH
- 12 ACH
- 20 ACH (Correct answer)
- 30 ACH
Correct answer: 20 ACH
ASHRAE 170 requires a minimum of 20 total air changes per hour for operating rooms to maintain sterile conditions and dilute airborne contaminants.
Question 2: What type of pressure relationship must an Airborne Infection Isolation (AII) room maintain relative to the adjacent corridor?
- Positive pressure
- Neutral pressure
- Negative pressure (Correct answer)
- Alternating pressure
Correct answer: Negative pressure
AII rooms must maintain negative pressure relative to adjacent areas to prevent airborne pathogens from escaping into the corridor and infecting others.
Question 3: Which ASHRAE standard specifically governs ventilation requirements for healthcare facilities?
- ASHRAE 55
- ASHRAE 90.1
- ASHRAE 170 (Correct answer)
- ASHRAE 188
Correct answer: ASHRAE 170
ASHRAE 170 'Ventilation of Health Care Facilities' is the primary standard governing ventilation system design in healthcare settings and is referenced by the FGI Guidelines.
Question 4: What is the minimum negative pressure differential required between an Airborne Infection Isolation room and the adjacent corridor per CDC and ASHRAE 170 guidelines?
- 0.001 inch water gauge
- 0.01 inch water gauge (Correct answer)
- 0.1 inch water gauge
- 1.0 inch water gauge
Correct answer: 0.01 inch water gauge
A minimum differential of 0.01 inch water gauge (approximately 2.5 Pa) is required to maintain consistent negative pressure in AII rooms without making doors difficult to open.
Question 5: What air supply system configuration is required for operating rooms to prevent cross-contamination between spaces?
- Recirculating system with HEPA filtration
- 100% outside air single-pass system (Correct answer)
- Variable refrigerant flow (VRF) system
- Fan coil unit with return air
Correct answer: 100% outside air single-pass system
Operating rooms require 100% outside air single-pass systems with no recirculation from or to other spaces to prevent pathogen spread between areas.
Question 6: Per ASHRAE 170-2017, what is the acceptable relative humidity range for operating rooms?
- 20–60% RH (Correct answer)
- 30–70% RH
- 40–80% RH
- 50–70% RH
Correct answer: 20–60% RH
ASHRAE 170-2017 updated the operating room humidity range to 20–60% RH, expanding the lower limit from the prior 30% minimum to reduce energy use without compromising safety.
Question 7: Which filter efficiency is required at the final filtration stage for operating room air supply systems per ASHRAE 170?
- MERV 7
- MERV 13
- MERV 14
- MERV 17 (HEPA equivalent) (Correct answer)
Correct answer: MERV 17 (HEPA equivalent)
ASHRAE 170 requires MERV 17 or higher (HEPA-grade) final filtration for operating room air supply to capture 99.97% of particles 0.3 microns and larger.
CHC MEP Systems in Healthcare Facilities 1
According to ASHRAE 170, what is the minimum number of total air changes per hour (ACH) required for an operating room?