Plastic pipes and flexibility
Plastic Pipes are classified by their ring stiffness. The preferred stiffness classes as described in several product standards are: SN2, SN4, SN8 and SN16, where SN is Nominal Stiffness (kN/m2). Stiffness of pipes is important if they are to withstand external loadings during installation. The higher the figure, the stiffer the pipe!
After correct installation, pipe deflection remains very limited but it will continue to some extent for a while. In relation to the soil in which it is embedded, the plastic pipe behaves in a 'flexible' way. This means that further deflection in time depends of the settlement of the soil around the pipe.
Basically, the pipe follows the soil movement or settlement of the backfill, as technicians call it. This means that good installation of pipes will result in good soil settlement. Further deflection will remain limited.
For flexible pipes, the soil loading is distributed and supported by the surrounding soil. Stresses and strains caused by the deflection of the pipe will occur within the pipe wall. However, the induced stresses will never exceed the allowed limit values.
The thermoplastic behavior of the pipe material is such that the induced stresses are relaxing to a very low level. It has to be noted that induced strains are far below the allowable levels.
This flexible behaviour means that the pipe will not fail. It will exhibit only more deflection while keeping its function without breaking.
However, rigid pipes by their very nature are not flexible and will not follow ground movements. They will bear all the ground loadings, whatever the soil settlement. This means that when a rigid pipe is subject to excessive loading, it will reach the limit for stress values more quickly and break.
It can therefore be concluded that the flexibility of plastic pipes is such that it offers an extra dimension of safety. Buried Pipes need flexibility9
Organization of major plumbing work in a block of flats
Plumbers working in a cooperative housing standard working hours from eight hours to the seventeenth or eighteenth. In such a time they can also perform plumbing work in a block of flats. More work done in a block must be well organized in such a way that it can be performed as soon as possible with the greatest respect for the rights of the people to preserve their privacy and quiet in the early morning. The tasks of the executives of the association must also ensure the safety of residents of the block during the works. They can apply to do the second division of water, clean water and sewage network or even replacement of water meters in all areas.
About water central heating
Circulating hot water can be used for central heating. Sometimes these systems are called hydronic heating systems.15
Common components of a central heating system using water-circulation include:
A supply of fuel, electric power or district heating supply lines
A Boiler (or a heat exchanger for district heating) which heats water in the system
Pump to circulate the water
Radiators which are wall-mounted panels through which the heated water passes in order to release heat into rooms.
The circulating water systems use a closed loop; the same water is heated and then reheated. A sealed system provides a form of central heating in which the water used for heating circulates independently of the building's normal water supply.
Heating systems in the United Kingdom and in other parts of Europe commonly combine the needs of space heating with domestic hot-water heating. These systems occur less commonly in the USA. In this case, the heated water in a sealed system flows through a heat exchanger in a hot-water tank or hot-water cylinder where it heats water from the regular potable water supply for use at hot-water taps or appliances such as washing machines or dishwashers.