Physically Separated : A gastight partition between two adjacent spaces, or two nonadjacent spaces, with no means of gas communication between the spaces
NFPA 820 Standard for Fire Protection in Wastewater Treatment and Collection Facilities, 2008 ed. http://www.nfpa.org/codes-and-standards/document-i nformation-pages?mode=code&code=820, (Std: Fr Prac in Wastewater Treatment and Collection Fcilty - Amer) {351 NFC}