![]() | Residential and Non-Residential - Drinking water installations and drainage requirements in Nepal (MTC - SKAT, 1988, 188 p.) |
![]() | ![]() | PART 2 - DRAINAGE REQUIREMENTS |
6.100 |
PRINCIPLE | ||
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To each water tap in buildings there belongs a drainage appliance (Exception: fire fighting equipment). | ||
6.200 |
DISCHARGE VALUE | ||
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The discharge value of soil and/or waste water of any drainage appliance depends on its function. | ||
6.300 |
OVERFLOW | ||
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Drainage appliances having outlets with stoppers (e.g. washbasins, kitchen sinks, bath tubs, etc.) require an overflow. |
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6.400 |
BACK FLOW PREVENTION | ||
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Drainage appliances have to be above the level of back-flow or are to be secured against exit of waste water by means of appropriate measures. | ||
6.500 |
PREVENTION OF EXIT OF GASES | ||
6.510 |
Siphon drainage appliance - Each drainage appliance (with exception of inlets, e.g. drain inlets) has to be fitted with a siphon to prevent the exit of gases. This siphon can be an integral part of an appliance or be directly attached to the outlet of the appliance. The pipe bore should be uniform throughout and have a smooth surface. | ||
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6.520 |
Siphon rainwater - Rainwater pipelines, from which disturbing odours may occur, are to be fitted with a siphon, fitted in a frost-secured place. | ||
6.600 |
REQUIREMENTS OF SIPHONS (traps) | ||
6.610 |
Water Seal - The siphon prevents the exit of gases by means of it's water seal. | ||
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h = |
height of water seal (odour lockage) | |
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for water closets, min. 50 mm | |
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for all other siphons, min. 70 mm | |
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S = |
level of water seal | |
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SL = |
(partial) loss of water seal (e.g. trough siphonage) | |
6.620 |
Self-cleansing - Siphons should always be of a self-cleansing pattern, by means of the discharged waste and/or soil water. | ||
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Anyhow, a cleaning opening must be provided. | ||
6.630 |
Placement of siphon - Siphons for use in domestic waste installations and all other siphons should be accessible. A siphon has to be directly attached to the outlet of the appliance, or to be an integral part of the appliance (e.g. water closets). | ||
6.640 |
Removable connection - Where openly fitted, such a siphon has to be easily fitted and removed. | ||
6.650 |
Concealed siphons - The construction and fitting of siphons must guarantee an easy removal of parts of the siphon and therefore enable easy access to the connector pipeline. | ||
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Where the siphon is an integral part of the appliance, the connector pipeline has to be accessible through either easy removal of the drainage apppliance (closet, urinal, etc.), or by means of reasonably placed cleaning openings. The cleaning opening has to be adjacent to the siphon or be directly part of it (e.g. floor drain with siphon). | ||
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Where the siphon is concealed in the building construction, with the exception of shower tray and bathtub, the possibility for cleaning is to be secured by means of a manhole or a cleaning opening. | ||
6.660 |
Guarantee of water level - To maintain the minimal required water level at each siphon, a permanent guarantee has to be provided by appropriate means. | ||
6.670 |
Water replacement - Closets and urinals with self-siphoning flushing systems have to be fitted with a device which replaces the water in the siphon automatically after each flushing. | ||
6.680 |
Mechanical odour barriers and aeration valves - both are prohibited for installation in domestic waste systems. | ||
6.700 |
Prohibition of direct connection with soil and/or waste water pipelines - Appliances, refrigerators, refrigerator plants, fish cabinets, food cabinets and other containers for food may only be connected to the soil and/or waste water pipeline by means of a inlet funnel. This same is also valid for drains of safety valves and other devices of the drinking water system. | ||
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gap to be of min. 2 cm, or of same diameter as inlet. |
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6.800 |
PROTECTION AGAINST POLLUTION OF PIPELINES |
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6.810 |
Protection from solid matter - no solid matter, such as sand, garbage, textiles, vegetable wastes, etc., may be fed into a drainage system. | ||
6.820 |
Protection from gross pollution - The outlet of a drainage appliance has to be constructed in such a way that no blocking solid matter may reach the siphon. The fitting of a kitchen waste chopper is prohibited. | ||
6.830 |
Closet arrangements - They have to be fitted with flushing cisterns, in order to guarantee the self-cleansing of the soil water system. |