Refrigerators can be placed in ISO classified areas, especially in negative-pressure HD buffer rooms. It is important to check any condenser pans monthly to avoid standing water and to wipe down the coils. If you can place it near or in front of low-wall returns, this be helpful. CriticalPoint has completed a couple of studies (to be published) showing no negative environmental impact when refrigerators are located in ISO classified rooms. I hope this helps.