Is the term for testing of systems designed to contain or resist the passage of fire for a specified length of time. The sample fire door, block wall, glass partition, fire / smoke damper or similar system is installed in a frame which is then placed on the open side or top of the fire testing furnace. The temperature in the furnace is raised by the computer control system to follow a prescribed time/temperature curve, and various checks for failure criteria are conducted to determine the time rating of the specimen. We now have four furnaces, one industry standard 3m X 3m vertical furnace, a 4m X 5m vertical furnace, a 4m X 5m horizontal furnace and a 1.8m cube furnace for 'indicative' (product development) tests.