Flexible Sprinkler Hose With Fittings - Hume Duct Type 1. In the process that the volatile gas or hydrogen chloride, nitric acid gas made in the semi conductor factory, is leaked outside through inner of the duct system, this product(sprinkler head) used inner of duct is helpful to firefight the fire early. 2. It is designed to resist the corrosion from hydrogen chloride, nitric acid gas and for the gas of duct inner not to leak into indoor.