Drainage Systems Lecture (I)

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Drainage Systems Lecture (I)

  1. 1. Lecture Notes 1 Sanitary Drainage systems 2 Table of Contents Chapter -1 Sanitary Drainage Fixture Units Page 1-21 1- Chapter -2 Vent system Page 22- 39 22- Chapter -3 Storm water & drainage systems Page 40-51 40- Chapter -4 Sizing the Underground Sewage Network for Buildings Page 52-74 52- Chapter -5 Septic tank capacity Page 75-87 75- Chapter -6 General example problem Page 88-96 88- Chapter -7 Sanitary Appliances & Arrangements Page 97-103 97- Chapter -8 Applications Page 104 References Page 122
  2. 2. Chap-1 Chap- 3 Sanitary Drainage Fixture Units The suggested values of DFU ( table 1 & 2) were designed for application in conjunction with the probability of simultaneous use of fixtures so as to establish maximum permissible drainage loads, in terms of fixture units rather than in numbers of specific types of fixtures or gallons per minute of drainage flow, for each of the various parts of sanitary drainage systems. In general, the sanitary drainage fixture unit value assigned to a particular fixture is based on the average volume discharged and the average rate of discharge for the fixture. This value is determined from the fixture’s total discharge flow, in gallons per minute, divided by 7.5, or, in other words, its total discharge flow in cubic feet per minute. Table 1 4
  3. 3. Table 1 5 Ref [2] 6 Table 2 Ref [2]
  4. 4. 7 By Size of trap Is used for fixture not listed in the previous table. For example example the floor drain with 2” pipe diameter ,the corresponding DFU is 3 Ref [1] Junction Box System 8 Bidet Bidet W.C. 4”UT Bath Numbe r Fixtures DFU Diamet er 1 Lavatory 1 1.1/2”- 2” 1 Bidet 1 1.1/2”- 2” 1 Floor drain * 3 3” 1 Bathtub 2 1.1/2”- 2” 1 W.C.s (flash 4 4” Tank), Total 8 F.U DFU
  5. 5. 9 Number Fixtures DFU Diameter 1 Lavatory 1 1.1/2”- 2” 1 Bidet 1 1.1/2”- 2” 1 Floor drain * 3 3” 1 Bathtub 2 1.1/2”- 2” 1 W.C.s (flash Tank), 4 4” Total 8 F.U DFU * Some references does not include F.D. in the calculation. A shower head over a bathtub does not increase the F.U. 10 Numbe Fixtures DFU Diamet r er Shower 1 Lavatory 1 1.1/2”- 2” 1 Bidet 1 1.1/2”- 2” 1 Floor drain * 3 3” 2 Bathtub 2*2 1.1/2”- 2” 1 W.C.s (flash 4 4” Tank), Total 10 DFU F.U
  6. 6. 11 Number Fixtures FU Diameter 1 Lavatory 1 1.1/2”- 2” 1 Floor 3 3” drain * 2 Bathtub 2 1.1/2”- 2” 1 W.C.s 4 4” (flash Clean out System Tank), Total 7 DFU F.U Drainage Stacks and Branches 12 Based on the computed drainage stack flow capacity for stacks flowing 7/24 full at terminal velocity, the velocity, corresponding number of fixture units may be determined from design load charts or tables (1,2 &3) so as to establish the total load which may be placed on a tall drainage stack. For example, the computed flow capacity for a 4-in (10 cm) 4- stack flowing at 7/24 full is 143 gpm (9.02 L/s). From design load charts or tables, it may be found that this rate of flow is equivalent to 500 fixture units. This is the total load that may be received from all branches on a 4-in (10 cm) tall stack. 4- However, to avoid excessive interference between flow entering the stack and that coming down the stack, it is necessary to limit the amount of flow, which may be, allowed to enter the stack at each of the branches. Thus, in a building of just a few stories in height, the amount of flow entering the stack through a branch may be greater than what would be permissible in a building of many stories.
  7. 7. Table 3 for sizing 13 drainage stacks provides different permissible loading for stack of more than 3 stories in height. height. Included in the table ,the maximum loads permitted on any horizontal fixture branch of a short stack. stack. Table 3 14 Vertical for Horizontal per each floor floor
  8. 8. 15 As a sample example : Calculate the total number of DFU , and size the horizontal branch connecting the two adjacent bathrooms , knowing that, The total fixture unit of each bathroom consists of (water closet, bidet, lavatory and bathtub or shower) = 8 FU’s FU’ Total fixture unit of two adjacent bath rooms connected to the same horizontal branch pipe is : 8 x 2 = 16 FU’s. FU’ As can be seen from table (3 ) for any horizontal branches , the 3” can handle up to 20DFU but , due to the presence of 3” the W.C.’s the 4” pipe diameter is selected which can handle W.C.’ up to 160 DFU. Table 4 for sizing 16 drainage stacks provides different permissible loading for stack of 3 stories or less in height and for stacks more than 3 stories in height. height. Included in the table are the maximum loads permitted on any horizontal fixture branch of a short stack and at any 1 story of stack more than 3 stories in height. height. Table 4 Ref [2]
  9. 9. 17 Slopes for horizontal drains are shown in (Table 5) , Which are applicable for building underground sewers and drains as well as those running at the level of the ceiling of basements, service tunnels, etc. Readers should note that the carrying capacity of horizontal drains is substantially lower than that for vertical pipes. Diameter of a vertical stack may have to be increased when it runs horizontally due to its reduced capacity in that position. 18 Table 5 For 4” Pipe diameter , having a slope of 1.04% , the Max. DFU is 180 , However if the slope is 4.2% , the DFU becomes 250
  10. 10. 19 Connections to Sanitary Building Drains Sanitary building drains are designed to flow half full at peak load. To load. avoid backup of flow from the building drain into branches, each branch connection to the building drain should be made to its upper half upper or its air-space portion. This may be achieved for 90 degrees branch air- connections by means of a one-sixth bend and a 45 degrees Y branch or one- a long-sweep one-quarter bend and a Y branch. The Y-branch fitting long- one- Y- may be rotated so that the branch is at 45 degrees angle above the the horizontal when the one-sixth bend is to be used and at a vertical angle one- when the long-sweep one-quarter bend is to be used. Less invert long- one- elevation is lost with the one-sixth bend and Y combination (see Fig ). one- 20 Two pipe system S.S. Vent pipe Vent pipe Vent pipe Figure 4
  11. 11. 21 One pipe system S.S. (Most popular ) Vent pipe Ref [2] Chap-2 Chap- 22 Vent System
  12. 12. 23 Introduction Sanitary drainage system of a building should be provided with an attendant system of vent piping designed so as to permit gases and odors in all parts of the drainage piping to circulate up through the system and escape into the atmosphere above the building and to permit the admission and emission of air in all parts of the system so that siphonage, aspiration, or back-pressure conditions will not back- cause an excessive loss of trap seal under ordinary under conditions of use. The sizing, arrangement, and installation of attendant vent piping should be designed so as to limit air-pressure variations in all fixture drains to a differential air- not exceeding 1 in (2.5 cm) of water column above or below atmospheric pressure. 24 A vent system is a pipe in a drainage system used : 1. To provide a flow of air to and from a drainage system so as to ventilate it. 2. To provide a circulation of air within such a system to eliminate trap siphonage and reduce back pressure and vacuum surge . 3. To insure the rapid and silent flow of waste
  13. 13. 25 Table 5 is used in sizing vents in accordance with drainage capacity loads. Permissible loads. lengths of vents are less than those computed by formulas (in which additional allowance need to be made for the equivalent length of pipe fittings) that the stated length may be applied directly as permissible developed length of pipe . This table is applied for vent stacks and branch vent sizing. Developed length of pipe = straight length of pipe + equivalent length of fittings 26 Ref [1]
  14. 14. 27 Ref [1] 28
  15. 15. 29 Ref [1] 30
  16. 16. 31 32 Traps. A fixture trap, illustrated in Fig. , is a U-shaped section of pipe U- of the necessary depth to retain sufficient liquid required by code. All fixtures and equipment directly connected to the sanitary drainage system are required to have traps. All traps must be vented in an approved manner, except for specific conditions waived by local code requirements or authorities. Ref [3]
  17. 17. 33 Ref [3] 34 Ref [3]
  18. 18. 35 Ref [2] 36 Ref [2]
  19. 19. 37 Ref [2] 38 Ref [2]
  20. 20. 39 Ref [1] Chap-3 Chap- 40 Storm water drainage system & Rain Water pipes
  21. 21. 41 Roof drainage systems A roof drainage system is composed of storm-water collection devices storm- located in the roof and piping , connected to the collection devices, devices, which transforms the runoff out of the building to the ground. Spacing and location of the roof drains are dependent on a number of locallocal conditions and building characteristics. Consideration should be given to such criteria as the local climatic conditions, type of roof, slope of roof, location of pipe chases, and available ceiling space to install install piping. It has been found that a storm producing a rainfall intensity 42 of 75 mm/hr may occur for 5 minutes once in 4 years, Can cause a serious damage .The rate of run-from roof +balconies .The run- is calculated as follows: A × P× R Q= [ m 3 / s] 3600 × 1000 Where Q = The rate of run-off from roof and balconies. run- A = effective area m2. P = impermeability factor which is 0.9 (concrete) For asphalt in good order is (0.875). R = Rainfall intensity mm/hr, ( 75-100 mm/h ) 75- For example: Calculate the flow rate from a concrete roof having an effective area of 50 m when the rainfall intensity is 75 mm/hr. 50 × 0.9 × 75 Q= = 0.001 [ m 3 / s ] that is 1 liter / sec . 3600 × 1000
  22. 22. 43 Roof Drainage Design Procedure The following procedure should be used in designing a roof drainage drainage system: (1) Lay out the position of the roof drains, deck drains and rainwater rainwater leaders. Consideration should be given to placing an overflow drain drain adjacent to each roof drain. (2) Determine the tributary area to each roof drain, deck drain, scupper, scupper, gutter, or rainwater leader. The tributary area is the surface area of roof that drains towards a specific drain. This tributary area should include the effects of runoff from adjacent walls which drain onto the walls, fig walls, (R-1) indicates the wall area that should be added to roof area to (R - determine the total tributary area for each drain. (3) Determine the routing and slope of the storm-water conductors. First, storm- determine the points from which, and to which, the conductors must be must installed. Then determine the space available for installing the storm- storm- water conductors. Finally, the routing and slope of the storm-water storm- conductors. 44 Fig (R-1) (R- Ref [2]
  23. 23. (4) Determine the rainfall rate to be used in sizing of the roof drainage drainage 45 system. The rainfall rate (also known as the rainfall intensity) is a term that relates the quantity of rainfall to a unit of time. Such rainfall rates rainfall are usually expressed in inches per hour or centimeters per hour. hour. (5) Determine the flow rate (volume per unit time) of equipment such as pumps, ejectors, air-conditioning equipment, and similar equipment air- which discharge into the roof drainage piping. Then convert these flow these rates into equivalent roof area. Flow rate is a term expressing a volume of water over a period of time such as cubic feet per second (cubic (cubic meters per hour), and gallons per minute (liters per second). The The following equations determine the roof area which will produce runoff at runoff a flow rate equal to the flow rate of the equipment: Equivalent roof area = 96/R * flow rate of the equipment ft² equipment Equivalent roof area = 359/R * flow rate of the equipment m² equipment where R is the rainfall rate used in the design of the roof drainage drainage system in inches per hour (centimeters per hour). The flow rate of the equipment is expressed in gallons per minute (liters per second). second). 46 (6) Calculate the total roof area drained by each segment of the roof roof drainage system. This calculation should include all roof areas calculated in step (2) and the equivalent roof area calculated in step (5). in Express the total area in square feet (square meters). (7) Determine the size of the roof drains and storm-water conductors or storm- the gutters and rainwater leaders. Sizes can be determined using table 1 through table 2. These tables list the maximum roof area in square feet (square meters) which can be handled by storm-water drainage piping of different sizes and slopes storm- for various rainfall rates. An example of Roof rain water distribution is shown in figure (R-2) (R- Area supplied by a drain pipe = = (Area of the balcony) +(area of the adjacent wall) + Part of the roof area.
  24. 24. 47 Size of drain pipe or leader (inch) 2 3 4 5 6 Rain fall rate Maximum tributary area (ft² ) (ft² (inch/h) 1 2,880 8,800 18,400 34,600 54,000 2 1,440 4,400 9,200 17,300 27,000 3 960 2,930 6,130 11,530 17,995 (4) 720 2,200 4,600 8,650 13,500 5 575 1,760 3,680 6,920 10,800 6 480 1,470 3,070 5,765 9000 Table (R-1), is used to size, roof drains, vertical rainwater leaders or storm water conductors. Ref [2] 48 Rainfall rate (in/hr) 2 3 (4 ) 5 6 Pipe sizing Maximum tributary area (ft² ) (inch) 3 1,644 1,096 822 657 548 4 3,760 2,506 1,880 1,504 1,256 5 6,680 4,453 3,340 2,675 2,227 6 10,700 7,133 5,350 4,280 3,566 8 23,000 15,330 11,500 9,200 7,600 10 41,400 27,600 20,700 16,580 13,800 12 66,600 44,400 33,300 26,650 22,200 15 109,000 72,800 59,500 47,600 39,650 Table (R-2),is used to size conductors or rain water leader installed at a slope 1/8 in/ft (1cm/m)
  25. 25. 49 Roof Rain water Drain Figure ( R-2) R- Example : “Sizing Rain water pipe” 50 Suppose we decide to size the rain water pipe ( shown in figure R-3) for a 5 floors building having the following data : 1- One pipe is used to collect the rain water from two adjacent balconies and part of the roof . This part of roof has a 65 m2 area ( refer to figure R-3) R- 2- The balcony area is 10 m2 each. 3- The adjacent balcony wall area is 15 m2 each ( refer figure R-1) Solution: Area supplied by the drain pipe = = (Area of the balcony) +(area of the adjacent wall) + Part of the roof area = [(2 x 10) x 5] + [(15x 2)/ 2 x 5) +65 = 195 m2 , that is (2166.6 ft2) [(15x From Table (R-2) a D= 4 in at 4 in/ hr Rain water intensity can handle flow from (R- from 2500 ft2 are . The 4 inch pipe is selected for this example.
  26. 26. 51 Roof Drain AREA OF ROOF PART = 65 M2 WALL AREA = 15 M2 WALL AREA = 15 M2 BALCON OF AREA = 10 m2 BALCON OF AREA = 10 m2 Figure ( R-3) R- Chap-4 Chap- 52 Sizing the Underground Sewage Network for Buildings
  27. 27. 53 Type of underground Drainage For buildings Separated Sewer Combined & rain water Sewer + Rain water system Fig( U-2) U- Fig (U-1) (U- 54 Drainage below ground connection Fig ( U-1) Separate System of drainage U- Ref [3]
  28. 28. 55 Fig ( U-2) Combined Rain + Sewer drain U- Ref [3] 56 Connections of the rain water Drain In the case of combined system ( Sewer +Rain water), rainwater water), must be connected to the foul water drain through a back inlet Fig. (U-3). (U- gully, to prevent the smell as shown in Fig. (U-3). In the case (U- of separate system ( Rain water only), it is not only), necessary to provide a trap before the rainwater pipe .It is connected to the surface water drain, and therefore a rainwater shoe, as shown in Fig. (U-4), may be used. (U- Fig. (U-4). (U-
  29. 29. Garage Drainage 57 The public Health Act 1936 section 34 defines certain prohibited discharges into drains or sewers as 1. anything that may injure a drain or sewer or interfere with the free flow or treatment and disposal processes, 2. hot liquids with a temperature exceeding 43.3 C, 3. petroleum spirit and calcium carbide. This means that the floor washings of large garages, petrol stations and indeed small garages should be Garage Gully trap provided with some means of Fig ( U-5) U- intercepting petrol before it enters the drain or sewer. For the floor washings of a small garage, it is sufficient to provide a garage gully as shown in Fig. (U-5). (U- Ref [3] Grease Traps (Fig,U-6) (Fig,U- 58 Special gullies for the collection of grease are not required for houses, but for canteen kitchens where the waste water from the sinks and dishwashers contains a considerable amount of grease they are essential. When grease is hot or contained in hot water, it is in the form of an emulsion, and if it is allowed to flow into the drain it will cool and adhere to the sides of the pipes. The principle of operation of the grease trap is that of cooling down the grease in a large volume of water, which will generally be cool, so that the grease is solidified and floats on the surface. At periodic Grease Traps intervals, the tray is lifted out of the Fig ( U-6) U- trap, which at the same time collects the grease. Ref [3]
  30. 30. Flow under gravity conditions ( Manning Formula ) 59 Manning , after carrying out a series of experiments , deduced the following equation which is the most commonly used for open channel flow and for water, sewer flows freely in pipes and conduits when both ends are open to atmospheric pressure . Calculations : 1.486 2 1 V = R 3 . S 2 (U .S units ) n 1.486 Q = A× × R2 / 3 × S 1/ 2 n Where Q= flow rate ft3/sec. A = Wetted area ft2, (half pipe cross sectional area) N= roughness of surface from table( ). R = Hydraulics radius (Area/wetted perimeter). S= Slope 0.5 -1 % from Chezy formula The determination of the hydraulics radius R for flow not running full 60 was explained before (chap-10 Dr. Hammoud lecture notes). (chap- In an open channel , the slope S can be determined as follows : Since the flow velocity is the same and the depth pressure does not change , the general energy equation becomes : P1 V12 P V2 + γ 2. g + Z1 − hL = 2 + 2 + Z 2 γ 2. g Z1 − Z 2 = hL We can express this equation on a unit of length basis by dividing both dividing sides by the length of the channel under consideration . Change in elevation divided by change in distance yields the slope : S = ( Z1 − Z2 ) / L = ( hL / L ) ( ft / ft ) or dimensionless dimensionless From the above formula , it is clear that the flow down is caused by caused the difference in potential energy or gravity . On the other hand the hand variable n known as Manning s , is a measure of the roughness of the channel . Table (U-1) lists the values of n for some of the more common (U- materials .
  31. 31. 61 The following procedure should be used in designing a the underground sewer pipe system: (1) Lay out should be drawn (2) The total DFU connected to the sewer pipe should be calculate. (3) From load tables convert the DFU to gpm or L/s, (4) Select the value “n” based on the pipe material. “n (5) Select a value of “S” , recommended underground slope “S” S=0.5-1 % . S=0.5- (6) Use Manning formula to determine the pipe diameter. Note : PVC pipe is used where n = 0.01 , flow Running half full & recommended slope is 1% . 62 Values of Manning’s n Table (U-1) (U-
  32. 32. Example 63 Water at the rate of 0.1 m3 /s flows through a 1 m pipe diameter vitrified sewer when the sewer pipe is half- full . Find the slope of the water , if half- Manning’s n is 0.013 . Solution : Given discharge , Q = 0.1 m3 /s Diameter of pipe D = 1 m Area of flow , A = ( 3.14/8) (0.5)2 =0.2777 m2 Wet Perimeter P = 3.14× D/2 = 3.14/2= 1.57m A 0. 393 D Hydraulic radius RH = = = = 0. 25 m P 1. 57 4 Manning s constant n = 0.013 Find the slope S: 1 2 1 0.2777 2 1 Q= A.R 3 . S 2 = (0.25) 3 . S 2 = 0.1 S.I. unit n 0.013 S = ( 0.1 / 8.477 )2 = 1 /7186 64
  33. 33. 65 66
  34. 34. 67 Manholes Usually constructed of brickwork, precast concrete or plastic. Shallow manholes, which sometimes called inspection chamber built in 113 mm of brickwork, providing that they are not in a road or waterlogged ground. Fig. (U-7) shows a detail of brick (U- manhole whereas Fig. (U-8) (U- shows A detail of a precast concrete manhole. Fig. (U-7) (U- Ref [3] 68 Fig. (U-8) (U-
  35. 35. 69 Dimensions of Brick Manholes Cover sizes for depths up to 2.7 m are 600 mm. x 600 mm, and for depths up to 3.3 m are 900 mm x 600 mm. For depths above 3.3 man access shaft may be constructed above the main chamber. 70 Precast Concrete Manhole
  36. 36. 71 Sitting of Access Points The Building Regulations 1992 require access to drains at the following points: 1. at a bend or change of direction; 2. at a junction, unless each run can be cleared from an access point. 3. On or near the head of each drain run; 4. on long runs; 5. at a change of pipe size. Figs (U-9), and (U-11) show the positions of access points. (U- (U- The distances marked “A” depend on the type of access, see Table R-. R- 72 Fig ( U-9) U- Ref [3]
  37. 37. 73 Fig ( U-10) U- Figure (R ) Junctions between drains and sewers. Note: 1,2,3 and 4 are alternative positions of the inspection chambers. 74 Ref [1]
  38. 38. Chap-5 Chap- 75 Septic Tank calculation The Septic tank capacity is calculated as follows: 76 The type of building & the number of persons is first calculated and then multiply by the average waste-water( table waste- S-1& S-2) per person a day . {Rain water is not included} S- {Rain For example : Suppose we decide to determine the septic tank capacity for a luxury home having 10 persons . From table (S-1) the daily (S- waste water per person is between 75-150 gpm /person/day . 75 - If we select 110 gpm as an average value Then the daily waste water flow is: 110 gpm x 10= 1100 gpm /day . The volume of the septic tank should be sized for at least 10-15 days (if no city 10- sewer net work is available ) & for 2 days [if a city sewer net work is available + pump (electricity cut -off)]. The vent pipe size for the septic tank is shown in table (S-3) (S- Practically for ordinary buildings a value of 200L-250 200L- L/Person/day is satisfactory.
  39. 39. 77 S-1 78 S-2
  40. 40. 79 S-3 80 1/3 L 2/3 L S-4 Length and structure of a septic tank Ref [1]
  41. 41. S-5 81 Septic Tank Capacity Ref [1] 82 S-6 Ref [1]
  42. 42. 83 84 Water -Drainage Pumping (Fig.) Wherever possible, drains should be laid so that the liquid flows by gravity to the sewer, or other point of disposal. In some cases, however, the water pipe or point of disposal is above the drain, and pumping is therefore required. For the pumping of surface water, a pumping installation as shown in Fig. ( S-7) may be used. S- For larger installations, two pumps should be installed, so that one of the pumps may be used for Stand –by purposes. This type of installation is used for basements and boiler rooms to deal with seepage of water, floor washing or the draining down of the boilers and Fig. ( S-7) S- heating pipe work, Ref [3]
  43. 43. Sump pumps (For waste water 85 drainage): The sewer pipes are located below the city network; in this case, a submersible pump will be used where the motor and the pump section are submersed in the liquid. Usually, two parallel sump pumps accompanied with automatic switches are used. Figure (S-8) shows the operation (S- principle of the pumps set .When the liquid reaches a certain level, pump (No 1) will start first, next to the second level, pump (No 2) starts according to the position of the level switches. For further safety, the system is accompanied with an alarm signal. Fig. ( S-8) S- 86 Fig. ( S-9) S-
  44. 44. Example: 87 Estimate the sump pump power required to evacuate a tank of 10 m3 in 30 minutes to the city network pipe. The height is 8 m and the total effective length L = 20 m. the material is smooth pipe type L. Take the unit head loss for 6 ft/100ft. Assuming an overall pump efficiency η =52% Solution: 10 m3 /30 min.= 333 L/min= 88 gpm Select the pipe size that can transfer 88 gpm at the recommended pressure drop. From the pipe flow chart of smooth pipe, the diameter is about 2.5” and corresponding 2.5” flow velocity is about 6.2 ft/s. From the general energy equation we get: hL = h1x L = (6/100) x20 = 1.2 m hA = Z1 – Z2 + hL hA = 8 + 1.2 ≅ 9.2 m Pout = γ x QV x hA = 9.2 x 9.81x 0.00555 = 0.5 Kw ≅ 0.68 hp 9.81x Pelec = 0.68/η = 0.68/0.52 = 1.3 hp. 0.68/η Chap-6 Chap- 88 General Example problem
  45. 45. 89 Example 3. Determine the diameter of the main waste and soil stack for a five-storey Motel, having 6 W.C.s (flash valve), 8 bathtub, 3 urinals –wall lip and 2 Lavatories (1.1/2”)on each floor connected to one single S.S. riser. From Table 1 ,2 & 3 Each floor 6 W.c.s, × 6 = 36 DFU , 8 Bathtub × 3 = 24 DFU 3 urinals × 4= 12 DFU , 2 Lav × 2 = 4 DFU Total = 76 DFU in each floor . From table (4) horizontal fixture branch for the 76 DFU ,the 4” is selected because it can handle up to 160 DFU. The same table shows that the vertical S.S diameter can be 4” since it can handle up to 90DFU per floor which is sufficient for the 76 DFU that connected in at each T-Y connection. 90 Number Fixtures DFU Total Diamet DFU er 8 Bathtub 3 24 2” 3 urinals – 4 12 2.1/2” wall lip 2 Lavatory 2 4 1.1/2” 6 W.C.s 6 36 4” (flash valve), 76 DFU Per floor =76x The Total for five floors =76x 5= 380 DFU
  46. 46. 91 Horizontal Vertical for per floor each floor At Basement floor connection Table 4 The total DFU for the whole Motel is 380 DFU: 92 30 W.c.s, × 6 = 180 DFU , 40 Bathtub × 3 = 120 DFU W.c.s, 15 urinals × 4= 60 DFU , 10 sinks × 2 = 20 DFU The Total for five floors = 380 DFU According to table (4) the horizontal branch connection at ¼ in 1 inch ft ( basement connection at high level) should be 5” .Since the 4” branch pipe can only handle 216 @ ¼ in per 1 ft whereas our requirement is 380 DFU @ ¼ in per 1 ft slope. The slope. 5” branch pipe can handle 480 DFU @ ¼ in per ft which is enough. As a Summary: The horizontal branch in each floor is 4 inch The vertical riser for the whole Motel pipe is 4 inch. The horizontal connection at the ground floor or basement is 5 inch.
  47. 47. Size the vent pipe 93 From table(5) four values of DFU is available for the 4” S.S 4” that is, 43, 140, 320 & 540 DFU . Our values is 380 which is between 320 & 540 DFU The higher value is selected (540 DFU ). The pipe diameter of the vent pipe handling 540 DFU at a 50- 50- 150 ft effective height is between 2.1/2” & 3”. The 2.1/2” 3” higher value is selected (3inch) Refer to the following schematic drawing Table 5 94 For 4” S.S. pipe the max. Roof FU 2" V.pipe is 500 76 DFU each floor 5 x76 =380 DFU less than 500 D Vertical 4" S.S. is enough 3" V.S. 4" SS. Total @ 1 story or 1 branch interval For 4" pipe ( maximum) 90 DFU 2" V.pipe 4" SS. Any Horizontal short fixture branch For 4" pipe ( maximum) 160 DFU 5" SS. Building drain or sewer connection pipe For 5" pipe ( maximum) 480 DFU @1/4 in per ft
  48. 48. 95 Now it is required to size the underground pipe diameter, S=1% ,flow half full, L= 100 m . As mentioned previously the total DFU = 380 ,the corresponding flow rate is 105 gpm = 6.63 L/s (from load table for flash tank) = 0.01 m3/s . The value of n =0.01 1 2 1 Q= A. R 3 . S 2 = 0.01 n 2 n × Q 0.01 × 0.01 A ×R 3 = = = 0.001 S 1/ 2 (0.01) 0.5 D= 0.15 m (6”) → This is the minimum diameter for the out flow of the building. 96
  49. 49. Chap-7 Chap- 97 Sanitary Appliances & Arrangements 98 Types of Sanitary Appliance WC Two-trap Siphonic WC Two- pan Single Siphonic WC (most Ref [3] popular)
  50. 50. 99 Urinals-types Ref [3] 100
  51. 51. 101 Baths Ref [3] There is a large variety of bath shapes Kitchen sink 102 There is a large variety of kitchen shapes Ref [3]
  52. 52. Kitchen sink 103 Ref [3] Chap-8 Chap- 104 Applications Fixture Connection & Pipe sizing From Reference [4]
  53. 53. 105 106
  54. 54. 107 108
  55. 55. 109 110
  56. 56. 111 Ref [4] 112 Ref [4]
  57. 57. 113 114 Ref [4]
  58. 58. 115 116
  59. 59. 117 Ref [4] 118 2” 2”
  60. 60. 119 H.W. 120 n 875 washer dish fridge 950 1425 fridge dish washer 338 500 338 1175 25 575 Draw & size the drain pipes The location of the Sewer Stack are shown
  61. 61. 121 H.W. Example 1. Find the internal diameters of the soil stack for 1. an eight-storey office, having five WC.s, and five basins on eight- WC.s, each floor, assuming public use of fittings. Example 2 Find the internal diameter (If the soil and waste stack for a four storey office having four W.c.s, and four W.c.s, basins on each floor, assuming public use of fittings. 122 Example 3. Find the internal diameters of the Rain water 3. riser pipe serving eight-balconies 10 m2 each . eight- Example 4. Find the septic tank capacity for Motel serving 4. 100 persons ( no sewer net work). Size the pump , and the corresponding vent pipe. Knowing that the septic tank must be recovered weekly. Project. The drawing entitled “taher” consist of 7 floors Project. taher” building . It required to: 1) Draw & size sewerage layout for each bathroom include the location and the size of the vent pipe. 2) Draw & size the drainage riser . 3) Draw & size the rain water pipes 4) Draw and size the underground septic tank
  62. 62. 123 References 1- Mechanical & electrical equipment for buildings –by Stein/Reynolds, Ninth edition ,John Wiley, 2000. 2-Practical Plumbing Engineering , Cyril M.Harris,ASPE,1998. 3- Building Services & equipment , F. Hall, Third edition, 1994. 4- Upland engineering , Mechanical consulting office, Dr. Ali hammoud.

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