Due to the high negative pressures that can occur in the systems, it is important that a resilient material is used with high resistance to implosion. Good quality HDPE pipe and fittings provide a good solution and ideally they should be made to EN 1519 the product standard for this material.
Another useful property of HDPE is that it can be fusion welded together removing the need for seal ring joints that may fail causing flooding of the building if the internal pressures force the joints apart.
In addition the system must be securely fixed with strong brackets especially if the pipework is hung horizontally some distance from the soffit of the slab. Systems are available which combine a steel rail and pipe brackets that restrain the pipework, which leaves the drop rod to deal only with carrying the dead weight of the pipework.
