Exam HFDP Topic 1 Question 114 Discussion

Actual exam question for ASHRAE's HFDP exam
Question #: 114
Topic #: 1
An Airborne Infection Isolation Room is 10 ft. × 12 ft. (3.05 m × 3.66 m) and has an 8 ft. (2.44 m) ceiling. An adjoining anteroom measures 6 ft. × 8 ft. (1.83 m × 2.44 m) with a 7.5 ft. (2.29 m) ceiling height. Airflow measurements reveal: Room supply diffuser: 135 CFM (64 L/s), Exhaust register: 200 CFM (95 L/s), Anteroom supply diffuser: 100 CFM (48 L/s), Anteroom exhaust register: 65 CFM (31 L/s). Which of the following represents the correct patient room air change rate (ACH)?

Suggested Answer: A Vote an answer

Comprehensive and Detailed Explanation:
Room Volume: 10 × 12 × 8 = 960 ft³.
ACH Calculation: ACH = (Airflow in CFM × 60) / Room Volume. For AIIRs, ASHRAE 170 uses exhaust airflow (200 CFM) since it determines air changes: ACH = (200 × 60) / 960 = 12,000 / 960 = 12.5 ACH.
Verification: Supply (135 CFM) < Exhaust (200 CFM) ensures negative pressure, consistent with AIIR requirements (12 ACH minimum, Table 7.1).

by Nora at Apr 07, 2026, 07:41 AM

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