Just what is a hydraulic descaler? A bunch of oil-operated pistons that lift the morbidly obese off of measuring equipment? A water-based solution for making thumbnails for your online image gallery? An empty nodeshell that caught somebody's eye in Random Nodes?
Some quick googling shows that a hydraulic descaler is an industrial device that uses liquid to clean scale (like limescale) from other industrial components. Some of the industrial processes using hydraulic descalers include removing scale from rolled steel in a steel mill, or the removal of caked-on gunk from oil rigs, vats, and deep fryers. One of the hydraulic descaling agents – whose makers assert this claim about cleaning up everything dirty from the production of petroleum to the production of funnel cakes – is based on butyls and is biodegradable. It's like a high-powered CLR without Billy Mays there to sell it to you.
Other types of hydraulic descalers can also be used to clean out complicated pipe-work like heat exchangers. Presumably, this would also be useful for the Internet, which is a series of tubes, and, as we all know, is occasionally blocked by buildup of porn, poker chips, and mortgage refinancing offers.
Further information, for which I have no commercial interest in linking:
http://www.sublimedescaler.com/degreasers-industrial-cleaners.html
http://www.bevelling.net/tube_descaler.htm
http://www.steellinks.com/pages/Rolling_Mills/Peripherals/Descalers/index.html