A machinery room houses a refrigeration system with a 300 kg charge of R-123. If the room has a floor area of 50 m², what is the minimum required exhaust ventilation capacity during a refrigerant alarm condition, according to CSA B52?

Question: A machinery room houses a refrigeration system with a 300 kg charge of R-123. If the room has a floor area of 50 m², what is the minimum required exhaust ventilation capacity during a refrigerant alarm condition, according to CSA B52?

Answer options:

• 300 L/s ✅ 750 L/s
• 500 L/s
• 1500 L/s

Correct answer: 750 L/s

Explanation: CSA B52 Section 7.2.1.2 mandates that mechanical ventilation, upon refrigerant detection alarm, shall provide at least 0.5 L/s per kilogram of refrigerant charge, or 0.25 L/s per square metre of machinery room area, whichever is greater, but not less than 150 L/s. For 300 kg, 300 * 0.5 = 150 L/s. For 50 m² floor area, 50 * 0.25 = 12.5 L/s. For R-123, CSA B52 requires increased ventilation to the lesser of 12 air changes per hour or 750 L/s. In this case 750 L/s is the minimum requirement.