A seal arrangement for sealing a space between a sterilization unit and adjacent walls in order to separate first and second rooms has a double seal gasket arrangement with a seal chamber there within. The seal chamber may be pressurized with a fluid and then the pressure within the seal chamber monitored by a pressure sensor. The double seal assembly provides an arrangement which can give an indication of the quality of the seal in order to detect any leakage and a more secure seal around the sterilization unit and as a result secure separation between a sterile or contaminated room and a general hospital area.