This document discusses the cold water supply system in construction technology and hydraulics. It covers topics such as water storage requirements, pipework layout, pipe sizing, and the drainage system. It also provides information on the sanitary plumbing and branch determination in the construction industry.
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Construction Technology 6 – Hydraulics1 CONSTRUCTION TECHNOLOGY 6 – HYDRAULICS Student’s Name Course Professor’s Name Institutional Affiliation City Date
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Construction Technology 6 – Hydraulics2 1)Cold Water Supply System In an office development, water storage requirement is based on the occupancy per net floor area. Occupancy is based on the floor area. In this proposed office block, the total lettable areas are as shown in table 1 below. Table 1: Floor areas for the proposed office building Office levelTenant (Lettable) floor area (SQM) Ground floor1083 Level 1869 Level 2700 Level 3496 Total3148 Water consumption is assumed to be 900 litres per day for an office space per 100m2 lettable area. Coldwaterrequirementperday=3148 100×900litres ¿28,8332litres Table 2: Water consumption for different buildings On the roof of the office block, above the staircase and lift lobby, 30 m3(5mx3mx2m high). Glass Reinforced Plastic water tank will be erected to store water for office use.
Construction Technology 6 – Hydraulics3 Since the water from the local authority supply is at 210 kPa (2.1 bar), there is a need for an underground water storage tank. This is because the pressure is low to pressurize to the roof storage tank and to the faucets and appliances in the office block. The underground tank is located in basement 2 and its capacity allows for 3 days storage. The tank is GRP type of capacity 80 m3(8mx5mx2m high) a)The pipework layout has been shown in the plan layout with mains from the authority supplying to the underground tank from where the booster pumps pressurize to the roof storage tank as well as branching to the office wet areas and kitchenettes. From the roof tank, the water flows via gravity to the office spaces. The main riser pipe from the underground water tank is made from Galvanized Mild Steel (GMS). These pipes are efficient in high pressure application. Internal reticulation to the office wet areas and kitchenettes is done in PPR pipes which are more flexible in use. b)Line diagram is as shown in the attached PDF document. The loading units and flow rates for different appliances in the development is as shown in table 2 below. Table 3: Loading units for different sanitary ware fixtures Sanitary appliance QuantityFlow rate (l/s)Loading unitsTotal loading units WC cistern250.12250 Urinal50.12210 Wash Basins240.12124 Kitchen sink40.22312 Total96 Along the pipe, the total flow rate is calculated from the below relation. Q=0.06(Lu)d Where Q= Flow rate in l/s Lu=Loading units
Construction Technology 6 – Hydraulics4 d=Diversity factor (63.5%) Therefore; Q=0.06(96)0.635 ¿1.07l/s Pipe sizing is dependent of the velocity of water flow as well as the flow rate as given in the relation below. InternalDiameter(ID)=35.68√Q V Where; Q= Flow rate (l/s) V= Velocity of flow (Usually 1.6 m/s) Therefore; ID=35.68√1.07 1.6 ID=29.17mm From class B copper tube chart extract shown in the figure below, 32 mm nominal diameter pipe is sufficient to supply water. Table 4: Nominal pipe sizes
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Construction Technology 6 – Hydraulics5 Water supply to individual sanitary appliance will be done in 25mm nominal diameter as this will be efficient for each appliance flow and velocity requirements. c)Pressure set capacity This is attributed by head losses due to friction, losses in fittings, elevation changes, and head gains due to pumps. Friction head loss hf=f[(LV2)/(2gd)] where; hf= head loss due to friction (m) f=friction factor (0.075) L=eeffective length (m) V=velocity (m/s) g=gravity (9.81 m/s/s d= internal diameter (m) hf=0.075[(50×1.62)/(2×9.81×0.032)] hf=15m Head Loss Due to Fittings hf=k(V2/2g) where; hf= head loss due to fittings (m) k=fitting loss coefficient (1) V=velocity (m/s) g=gravity (9.81 m/s/s hf=1(1.62/2×9.81) hf=0.1m
Construction Technology 6 – Hydraulics6 Head Loss Due to height of the building Vertical height of the building=25m Total head is given by the sum of the above; Friction head loss + Head Loss Due to Fittings + Head Loss Due to height of the building ¿15m+0.1m+25m ¿40.1m(410kPa) Pressure set capacity should be at least 1.07 l/s (3.85 m3/hr.) at 40.1 m head. 2)Roof Areas Drainage a)Assumptions Storm Intensity Calculations Roof drainage design is a function of roof area and rainfall intensity. In Maitland, rainfall intensity is estimated to be 50mm/hr. Flow rate is calculated from the following relation; Q=(RoofArea×Rainfallintensity×Runoffcoefficient/3600) Q=¿ Q=77l/s This flow rate will be drained by 17Nos 100mm PVC downpipes each of flow capacity of 4.6l/s. b)Sigle line diagram The line diagram is shown in the PDF document attached. c)The OSD size is based on an hour’s downpour at a rate of 80l/s per ha. Therefore, for 0.154 ha, the amount of water to be collected will be given by the following relation; Capacity=0.154×80l/s×3600sec
Construction Technology 6 – Hydraulics7 Capacity=44,352litres The approximate capacity of the OSD pit is 48 cubic metres (6mx4mx2m high) 3)Sanitary Plumbing and Drainage System a)Pipework sizing. The drainage stack pipe sizing is based on the discharge units from sanitary fixtures. Table 5: Discharge units for sanitary fixtures Sanitary fixtureQuantityDischarge unitTotal discharge units WC2414336 Urinal Bowls50.31.5 Wash Basins24372 Kitchen Sink41456 Total465.5 Branch determination is based on the type of drainage system used. In this case, single stack system is used with one stack and soil vent pipe. Branch pipes are as per the Australian Standard AS 3500 part two as shown in the figure below.
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