ATCO’s UL Listed pressure ratings are determined by testing ducts in straight lengths, at ambient temperatures. Testing is done in a static condition (no airflow). The test sample is sealed airtight on both ends and pressurized to 2 ½ times the manufacturer’s desired rated pressure for a test period of one hour. A minimum of 1 1/4″ of positive pressure must be achieved in order to pass the test.
ATCO performs some additional tests in accordance with the Air Diffusion Council, FD 72-R1 Flexible Duct Test Code. The purpose of these tests is to simulate a variety of realistic conditions, which may exist in actual installations. The ADC tests include a 90 degree bend, heated air at continuous and intermittent temperatures, for a test period of 168 hours. The resulting “Recommended Operating Pressures” are intended to give the contractor and/or engineer a responsible guideline within which to design the duct system.