... ---not decay, mildew, durability.Fire---resistance.Practicality: suitable for the densely-populated area (such as school, supermarket, ... such as hospital, laboratory, howff, bus, train, broadcasting studio.PROPERTIESVALUEDiameter Range75-750mm (3"-30")Temperature Range-30 ~ +250 ... usage and low wind resistance, and specifically produced for low and medium pressure heating, cooling, ventilation, air ...