DOMESTIC & COMMERCIAL PLUMBING SYSTEMS FURTHER INFOMATION

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1 DOMESTIC & COMMERCIAL PLUMBING SYSTEMS FURTHER INFOMATION Hot and Cold water distribution pipework Sizing of pipework For everyday plumbing in an average sized building a rule of thumb can be used when sizing pipework for the hot and cold water supply, which consists of 15 / 22 / 28mm pipework; in the case where you may have more than 2 draw off points 22mm would be chosen and where there may be more than 6 draw it may be necessary to use 28mm, with runs reducing down to 15mm as necessary to each appliance. For larger systems with many outlets over a bigger area and / or several floors the distribution pipework needs to be sized correctly to ensure sufficient pressure and flow at the draw off points. Types of piping Previously where the water requirement to buildings consisted of only a cold supply to a single tap, cheap plastic piping could used but now most compounds are constructed with western type bathrooms, showers and hot water is piped to all appliances, so it is essential that pipes are sized correctly to achieve the desired pressure and flow at the draw off points and the correct quality type of pipe is used which is robust, suitable for both hot and cold water supply and is capable of withstanding higher pressures. If the wrong type or an inferior type of pipe is used it can lead to leakage and the breaking down of the system within a very short time, which can be extremely costly, disruptive and can even result of the system being completely re-plumbed. It must also be ensured that different types of pipe used together are compatible; for instance if galvanised iron and copper pipes are used together on a hot water system, the zinc on the iron pipe will corrode quickly and eventually rot completely.

2 Modern plastic plumbing piping comes various sizes, in rolls up the 100 metres. They are suitable for both Hot and Cold Water Supply, will take up 10bar pressure, are easy to join with push fit fittings, and quick to install Connections to appliances The hot and cold supplies to a shower will need to be of equal pressure to ensure good operation of the mixer valve. The height of the cold water storage tank must be at least 1 metre from the underside of the storage tank to the level of the showerhead for adequate pressure to be achieved but some showers require a greater pressure and this should be checked before purchase, or they will not operate correctly. This is also true of many of the taps that are sold through plumbing shops in Freetown and Banjul; often the taps have small connection hoses and will only achieve a good flow rate if connected to high pressure systems. As all systems are indirectly fed from a cold water storage tank in these countries, the only way of achieving higher pressures is by using an in line pump, which where there is no electrical supply or the supply is intermittent causes further problems. If all of these factors are considered, with good design of the system most of these issues can be avoided.

3 To ensure the correct operation of a shower the cold water storage tank should be a minimum of one metre measured from the base of the tank to the top of the rose on the shower Installation of pipework Pipework should be installed so that the pipe is adequately supported and clipped to prevent sagging and to prevent damage. Pipe runs should be kept as short as possible (especially for hot supplies) and tight elbows kept to a minimum. It is also desirable to insulate hot water runs to prevent heat loss. Full flow isolation valves should be fitted at the point of connection to each appliance where possible, for ease of future maintenance. High spots and dips should be avoided, which may allow air to trap causing a blockage. Often it is desirable that no pipes are visible and a chase is made to the wall, its important that the pipe is protected from any cement attack and the pipes are allowed some free movement to contract and expand. Where possible it is better for the pipework to be fitted in an accessible duct to allow access for any maintenance or future alterations. When passing pipes through walls, the pipe should be sleeved to allow movement. Before any pipes are plastered into the walls or concrete floors they should pressure tested for signs of any leakage, once pipes are found to be leaking in the wall / floor it has to be chiselled out to make any repairs. Above ground soil & waste drainage systems When an appliance (wash hand basins, showers, WC etc) has been installed it is then connected to the above ground sanitary pipework. The connection is made via a suitable trap, which is a fitting or an integral part of the appliance as with a WC pan. The purpose of the trap is to prevent foul smells passing through the appliance, its important that the trap seal is

4 the correct depth to prevent any trap seal loss; in general the depth should not be less than 75mm. The system of above ground drainage is designed to transport all the foul and waste water to the below ground drainage system and then on to the septic tank. The soil stack must always incorporate a ventilation pipe at the highest point, and then extended to the atmosphere at a point where the bad air can escape without causing a nuisance. It is essential that that air is allowed to enter the drainage pipe system, to prevent a build up of foul air and stop any self-syphonage on the trap seals. The sizing of the soil stack and branch waste pipework will be dependant on the amount and type of appliances but for most average size compounds the soil stack should be a minimum of 100mm diameter. All soil and waste pipework should incorporate a fall to allow the water to discharge freely; any horizontal soil pipes must be set at a self cleansing gradient. The branch pipework should incorporate cleaning eyes where necessary for the easy removal of any blockages. Any drainage system should be kept in sound condition and any leakage attended to straight away. Occasionally drainage pipes can become blocked due to a number of reasons but these incidents can avoided to some extent if sanitary towels or other cotton items are not be flushed down the toilet. Blockages should be cleared immediately to prevent a build up within the drainage system which if left unattended to will harden in the heat and be very difficult to move with drain rods. Its very important on a septic tank system that harsh chemical are not used for cleaning or unblocking purposes, as this may destroy the bacterial process which allows aseptic tank system to function correctly.

5 Soil and waste pipes should be installed to a self cleansing gradient with cleaning eyes to allow access to remove any blockages

6 Bathrooms, wet rooms, showers & sinks Sanitary Appliances Sanitary appliances are divided into 2 groups, those that are used for washing / ablutionary purposes and those which are used for the removal of human excreta. Waste appliances include: Sinks Wash-hand basins Bidets Showers Baths Sinks should be set at a height of no more than 900mm. Wash-hand basin heights are usually determined by the pedestal but where brackets are used the height should be between mm. Bidets are appliances for washing the lower parts of the body and are normally floor standing, as with showers if the bidet incorporates a spray head, then the hot and cold connection must be of equal pressure. In many cases in Sierra Leone and The Gambia shower rooms are constructed so the entire floor is sloped to discharge water to a floor gully, the gully should also incorporate a trap seal and the grating should be so it can be removed internally for cleaning purposes. Soil appliances include WC pan Urinals In recent years many of the flushing toilets that are available at the local plumbing shops use a flushing mechanism that lifts a diaphragm to allow water to flush the pan, these may be suitable for Western societies where they are connected to a sewage system but they have a tendency when they malfunction to allow a constant stream of water to run into the pan, which may go unnoticed or left unattended. Not only does this waste valuable water but it fills the septic tank chambers up and can lead to an overspill at around the septic tank, which is a health hazard. Where possible if a flushing WC is required its better to use one that use the siphon type lift mechanism type cistern as when this malfunctions the cistern will not operate but no water will constantly run into the pan Although urinals are not commonly used, the height of the lip of the bowl / trough urinal should beset at 610mm and for junior boys at a height of 510mm. Sanitary Accommodation. Its important that the layout of the sanitary fittings within the space available should be carefully considered at the planning stage, there s nothing worse that trying to use a toilet or wash-hand basin where there s no room to manoeuvre or your knees are crowed against a wall. The following criteria should be observed when positioning sanitary ware.

7 The dimensions of the human body, allowing for sufficient room to move and use the appliance for the purpose its meant for The number of persons using the facility The size of the sanitary ware, its purpose and the location in relation to the rest of the sanitary ware appliances Enough space should also be provided to gain access to the trap for cleaning and maintenance. An example of sanitary accommodation requirement