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1, all water supply pipe and casing is due to the pump or water flow will cause the pipeline to produce vibration pressure, if the casing will be because of the casing and the filler between the role of the pressure and make the buffer, In a long time after the wall cracks and thus affect the appearance.
2, easy to construction. If you do not reserve casing, in general, is to ask the building to do concrete box to fight the concrete. This is the completion of the pipeline after the installation, civil workers have to deal with the other side of the hole, far from the original stay tube was convenient and quick.
3, easy to repair. If the pipeline for some reason to be replaced, the casing is much more convenient.
4, for those who may often have water on the ground room, such as, etc., casing 20mm higher than the decorative surface, will prevent the water flow down the pipe. Especially the reserved bushings, which have a good contact with the ground that has been waterproof, and the water resistance is much higher than those that have been reserved for holes.