NFPA 45 recommends 4 ACH even when the lab is not occupied. Some other ACH ranges are reported as follows:

OSHA 1910.1450 Appendix A Section C.4(f) Normally adequate  4-12

NFPA-45 Typical for occupied laboratories

Minimum for unoccupied laboratories 4

Typical for occupied laboratories >8

ASRAE Applications Handbook Minimum range 6-10

National Research Council Normally adequate 6-12

AIA  4-12

ANSI/AIHA Z9.5 None given

Good morning all:

A similar topic on lab ventilation came up in DCHAS a number of years back, but I would like to dig a bit further. I am interested in your thoughts and feedback, especially if any new recommendations/best practices have been made, particularly in academic laboratories.

1. What minimum air changes per hour (ACH) do you require for the following laboratories while occupied?
• Instructional/teaching lab
• High risk research lab
• Low risk research lab

Follow up – what criteria do you use to classify high risk vs low risk research labs?

2. Do you reduce the ACH for unoccupied laboratories?
3. Has anyone done Computational Fluid Dynamic (CFD) analysis of their typical labs to validate that the air flow rates and directions are sufficient?

I’m reviewing our current practices, and looking at adopting from ANSI Z9.5 2012 and ASHRAE TC9.10 (some familiar names as contributors).

Your comments are greatly appreciated.

Steve

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