Water supply and drainage (VW)

General part

General instructions.

Tasks and Design Input.

  The course design is carried out in accordance with the assignment for the design of cold water supply and sewerage of a residential building according to the initial data. At the same time, it should be borne in mind that the building has the same floor layout and an unexploited basement located under the building.

 The height of the attic space is taken to be two meters.

 The building is supplied with cold water from the city water supply network shown on the plot plan. 

  Hot water supply of houses is taken centralized according to an open scheme, with direct water collection from the CHP. Removal of household wastewater from residential buildings is accepted into the street sewage network.

  The course design includes a calculation explanatory note and a graphic part made on two sheets A1.

Design Input:

Standard Floor Plan Variant Number 5                             

Number of floors 4                                              

Floor height (from floor to floor) with floor thickness 0.3 m, m 3.0       

Basement height (to ground floor), m 2.8                          

Site 3 Plot Plan Variant Number                                   

Distance from the red line to the building l1, m 10                        

Distance from the building to the city sewage pit A l2, m 14   

City water pipe diameter, mm 300                        

Diameter of city sewage pipe, mm 350                         

City sewage pipe slope 0.007                            

Absolute elevation of the ground surface near the building, m 39.4                

Absolute floor elevation of the first floor, m 40.2                        

Absolute elevation of the well tray A of the city sewerage system   , m 36.0   

Depth of seasonal ground freezing, m 2.5                          

Warranty head Ngar., m 42                                        

Average occupancy of U apartments, person/apartment   3.2                   

2. Plumbing design.

  For residential buildings of a small storey with basements , a dead end scheme of an internal water supply with lower wiring is adopted.

  For preliminary judgment on providing the internal water supply system with pressure from the city network. Therefore, the guarantee head is Ngar. with the normative free pressure of Nsv.n . according to SNiP II3174.

  For single-storey buildings, the standard free head Nsv.n. is taken equal to 10 meters. For multi-storey buildings, 4 meters are added to each subsequent floor.

Nsv. N = 10+4n

  If Ngar. it turns out to be more than or equal to NSW, therefore, the operation of the internal water supply system is ensured by using the head of the city water supply network.

   If Ngar. it turns out to be less than Nsv.N., then in the building it is necessary to provide an increasing installation with working and standby pumps.

  After selecting the system and the internal water supply scheme, they begin a structural study of individual elements.

  The internal water supply consists of the following elements:

- input;

- water metering unit;

- water supply network (divided into main line, risers and supply);

- reinforcement.

  The plumbing input is designed at right angles to the wall of the building and should be as long as possible. Most often, it is advisable to design an entry in the middle of the building.

 With the number of apartments up to 400, one entry is accepted, with a larger number of 2 or more. Steel galvanized pipes GOST 326275 are used for the device for the introduction of drinking water supply. 

Depth of input laying is taken depending on depth of urban water supply pipes laying and depth of ground freezing.

  The depth of pipes laying is accepted in accordance with SP 31.13330.2012 below the depth of seasonal ground freezing by 0.5 m.

  The inlet is laid with a slope of 0.0020.005 under the building.

  Water metering unit is located directly behind external wall at height of 0.6 m above level of basement floor.

 In front of the water metering unit, it is advisable to provide a straight section of the pipeline with a length of at least 1 meter.

  Counters are of two types: impeller and turbine.

  Impeller counters are installed on flanges or couplings and only on horizontal sections of pipes.

  The turbine meters can be installed in any position.

  Water supply risers are located in sanitary and kitchen hubs.

  Water struts on plans of the floor and basement and also on axonometrical schemes have to have numbering and be designated as follows: ST of B11, ST of B12.

  Steel galvanized pipes GOST 326275 are used for internal water pipelines. 

  The main line within the basement connects the riser bases with the water metering unit. The main line is laid with a slope of 0.0020.005 towards the water metering unit. Valves are installed on the branches from the main line to the risers.

  Watering cranes are connected to the main water supply line with a slope of 0.0020.005 towards the watering crane to allow water to descend from them for the winter period.

  The supply from the risers to the water discharge valves is laid with a slope of 0.0020.005 towards the riser, horizontal sections of the supply should be located above the floor at a height of 0.10.3 m. On the supply pipelines it should be provided for the installation of valves with a diameter of 15 mm. The vertical part of the supply pipes is removed above the floor by 0.8m for mixers with a shower and 1.1m for a washing mixer (in the kitchen).

Calculation of cold water supply system.  

  To supply water for household and drinking needs in the building, a system of household and drinking water supply is installed, supplying water to sanitary and technical devices installed in 16 apartments and serving 60 people.

Internal water line axonometry and hydraulic calculation

  The calculation of the internal water supply network provides for the determination of design dimensions, the assignment of pipe diameters and the determination of head loss along the length and in local resistances.

  The network calculation is carried out on the action of water collecting devices located highest and farthest from the input. Such water disassembling devices are called dictators.

  When detecting dictating water disassembly devices, the value of the free standard head in front of them should be taken into account. Further, the water supply network on the axonometric diagram is divided into calculated sections according to the selected direction from the dictating water disassembly device to the input to the building inclusive. For this purpose , design points are arranged in places of installation of water-discharge valves in the selected direction. Keep in mind that the water flow rate and pipe diameter must be constant within the design area.

Sewerage Design

  On the sewage plan, sewage risers are applied for each group of devices. The risers are placed in the bathrooms, if possible closer to the toilet, so that the length of the branch pipes from the other water receivers is minimal.

  Sewage risers on all plans and on the axonometry are indicated as follows: St K 11, St K 1-2.

  The diameter of the sewage riser is taken depending on the flow rate of waste water and the largest diameter of the intraquarter wiring.

The diameter of the sewer riser shall not be less than the largest diameter of floor branches connected to this riser. And the diameter of floor branches is taken structurally, depending on the diameters of exhaust pipes from devices (when installing the toilet, the diameter of floor branches is 100 mm, in other cases the diameter of floor branch is 50 mm). Pipe material: plastic, cast iron, asbestos cement.

  For ventilation and removal of sewage gases, the risers are discharged above the roof level by 0.5 m.

  For horizontal sections of the sewerage system, the axonometric diagram indicates the slope, diameter and length.

  The normal slope for pipes with a diameter of 100 mm is 0.02, for pipes with a diameter of 50 mm is 0.035.

  Discharges from risers are traced through the building wall, and on the basement plan the locations of wells of internal or internal sewage are indicated. The number of issues is equal to the number of sections of the building. It is recommended to lay the releases under or near the stairwell. The length of the exit from the building is taken to be from 3 to 5 m.

  The releases indicate the diameter, length and slope of the pipe, and the releases themselves are numbered.

  The plan must show the well, its number, diameter, depth of laying and elevation of the ground near it.

  Also on the axonometric diagram, it is necessary to show sewage receivers on the upper floor, show the inspection well on the outlet, indicate the number of the well with a diameter of 1m, the depth, as well as the elevation of the ground surface, the outlet pipe tray and the well tray. On the axonometric diagram it is necessary to show all shaped parts, hydraulic closures, revisions, cleaning, etc. Revisions on the riser should be located in the basement, on the first and last floors, at a height of 2 floors. To turn the riser to the outlet, a flat elbow or two branches of 135 are used. Cleaners are installed in basements on turning sections.

  Releases from the building should be designed at right angles to the outer wall.

  In case of a large deepening of the external network, at the outlets it is allowed to device swings. If the drop is up to 0.3 m, it is made open along the concrete spill with a smooth entrance to the well. If more than 0.3 m, it is closed in the form of a riser with a section not less than the section of the supply pipe, or it is performed in a separate transition structure. The diameter of the outlet for low-rise buildings is taken equal to the largest diameter of the connected riser. For buildings with more than 9 floors, the diameter of the outlet is determined by hydraulic calculation.

  The diameter of the yard sewage pipes is from 150 mm or more.

  Filling for pipes with a diameter of 150 mm is recommended to be taken from 0.3 to 0.7.

  The flow rate of waste water in the pipeline shall be not less than 0.7 m/s.

  The yard network is applied to the plot plan of the section, while at 1.5-2 m from the red line there should be a control well, which can be combined, that is, additionally perform the functions of a rotary or differential well.

 

Hydraulic calculation of sewage system

Hydraulic calculation is performed only for horizontal sections of the sewerage system from the outlet from the building to the city sewerage pit.

Connection of sewage outlets to the yard network is made from silk to silk.

Silk - top of pipe, tray - bottom.

If necessary, the drop should be designed in the control sewer, which is located in front of the red line.

Based on the results of the calculation, a longitudinal sewer profile is built.

The length, diameter, and slope of the pipeline are mandatory for all sections of the network.