Plumbing, Sanitary, Gas and Swimming Pool Services by Ng Han Siong 20 Nov 2012

1. Plumbing, Sanitary, Gas and Swimming Pool ServicesbyNg Han Siong20 Nov 2012

2. Plumbing, Sanitary & Gas Services- Codes & Regulations The design and construction of the Plumbing, Sanitary, Gas and Swimming Pool Systems govern by the following codes: • Cold and Hot Water System • CP 48:2005 Code of Practice for Water Services. • Sanitary Plumbing and Drainage System • Code of Practice on Sewerage and Sanitary Works • Code of Practice of Environmental Health • Gas System • CP 51:2004 Code of Practice for Manufactured Gas Pipe Installation. • Swimming Pool System • Code of Practice of Environmental Health • Other Codes, Standards, Regulations referred to by the above codes. • Plumbing Engineering Services Design Guide published by The Institute of Plumbing

3. Plumbing Services • Mode of Supply: • Potable Water • Highest fitting below 125m RL – Direct • Highest fitting above 125m RL but below 137m RL – Indirect through high level storage tank • Highest fitting above 137m RL – Indirect via low level tank with pumping to high level tank • Newater • Highest fitting below 115m RL – Direct • Highest fitting above 115m RL - Indirect

4. Plumbing Services • Direct Feed • Highest fitting < 125m RL

5. Plumbing Services • Indirect Feed • 125m RL < Highest Fitting < 137m RL

6. Plumbing Service • Indirect Feed • Highest fitting > 137m RL

7. Plumbing Service • High rise buildings with multi-stage pumping

8. Plumbing Services • Water Storage Tank Sizing • High level storage tank – 1 day storage capacity • Low level transfer tank • Low Level tank inlet between 125m and 130m RL, min. 1/5 of the daily water requirement. • Low Level tank inlet above 130m RL, min. 1/3 of the daily water requirement.

9. Cold water storage Capacity • As a general guidance, use the following recommended figures to determine the domestic water storage tank capacity.

10. Recommended water consumption

11. Worked Example of Institution Water Storage Calculation

12. Estimated Water Requirement

13. Flow Determination For domestic usage, it rarely happens that all the appliances installed are in simultaneous use For economic reason, usual design practice is base on simultaneous usage that less than the maximum possible The simultaneous demand can be determined by using loading unit concept For industrial and process applications should be designed for their full flow rate

14. Plumbing Services Flow Determination From Loading Unit to get the flow rate. Chart D-1: Loading Units & Design Flow Rate

15. Plumbing Services Flow Rate Calculation – Use Loading Unit Say the water distributing pipe feeding 10 WC (water flushing cistern), 20 wash basins and 10 baths: 10 WCs - x 2 = 20 20 wash basin - x 1.5 = 30 10 baths - x 10 =100 Total Loading Unit =150 LU The flow rate for 150 LU read from chart D-1 is 1.8 l/s.

16. Plumbing Services – Flush Valves say 8 nos. • For premises under Group A: 3 x 1.5l/s = 4.5l/s. • For premises under Group B: 4 x 1.5 l/s = 6.0 l/s Flow rate calculation

17. Plumbing Services Pipe Sizing From the flow rate, determine pipe size from Chart 2 Assume velocity • Up to 2.4 m/s for flush valve • Up to 1.5 m/s for other fittings

18. Plumbing Services • Flush Valve Design Considerations • Use for WC and Urinal (a must for public toilet) • FV for WC c/w check valve • Every FV control by a stop valve • Direct feed up to 115m RL • Pipe serve WC shall be min. 25mm internal dia.

19. Water Pump Sizing • Ppump = Ps + Pp + Pf + Pd • Ps – Static Pressure • Pp – Friction Loss in Pipe • Pf – Friction Loss in Fittings • Pd – Discharge Pressure Loss (~ 1.5 bar) to drive water through final plumbing fixture • To allow pump redundancy (i.e. 2 x 100% or 3 x 50%) • To provide VSD for energy conservation

20. Water Pump Sizing • Transfer Pump must be able to fill up the roof tank in 4 hours Table F-4: Equivalent Pipe Length (Meter Run of Pipe)

21. Hydro-pneumatic Tank Sizing • Why hydro-pneumatic tank is needed? • to control pump cycle when the demand is significant lower than the pump capacity. Minimize pump start and stop • without it, pump will start and stop constantly even at low flow. It will produce pressure transient that will damage the pump and piping system • Typically located downstream from pump station

22. Pressure Vessel Sizing Vessel Size (litres ) = V / f V, vessel storage vol. (litres) By Boyle’s Law formula V = (15 x Q ) / i Q = Mean flow rate (litres/min) i = No. of pump cycle per hour Acceptance factor, f f = (Po – Pi) / Po Po = Cut – out pressure (abs/in bar) Pi = Cut – in pressure (abs/in bar) f -Volume of water a tank is design to hold. Acceptance volume for bladder tank is Smaller than the tank volume

23. Pressure Vessel Sizing • Sample calculation

26. Design Considerations 1) Do not conceal pipe in column, beam and floor slab, except for smaller size water pipe that allow to conceal in brick-wall. 2) PUB no longer approve the water fittings directly. All fittings used have to follow a stipulated standard. A water fitting is deemed to comply if it is certified or tested as complying by an approved body (such as PSB). For example: copper tube to BS EN 1057:1996, FRP/GRP sectional water tank panel to SS245: 1995. 3) Consult PUB on bulk meter position and existing water main pipe to be tapped from. 4) For risk and safety consideration, do not locate water pipe over any electrical transformer / switchgear or other water sensitive room such as computer room, etc. 5) Avoid laying potable pipe under any non potable pipe. Avoid non potable water pipe running above water tank. 6) Always locate the water tank manhole access cover above or near the ball float valve for inspection & maintenance purposes 7) Note the nuisance that might be caused by the operation of the transfer pump and water filling up noise in water tank especially for residential development. Locate the plant room away from apartment unit or provide adequate noise control measure. 8) Always consult your QP early on your preliminary design concept before proceeding full speed ahead (0%, 50% and 100% checks).

27. Design Considerations For Cold Water Supply System 9) Take note WEL requirement 10) Long bath/jacuzzi exceeding 250 litres shall have recycling facilities. 11) An air gap of minimum 150mm shall be provided for water inlet pipe to non-potable water usage such as fire tank, irrigation tank and water feature.

28. Sanitary Services - Terminology • Sanitary Drainage System • Underground pipework - drain-lines, branch drain lines, fittings and ICs to convey sewage to sewerage system • Sanitary Plumbing System • Aboveground pipework - discharge pipes/stacks, ventilating pipes/stacks and fittings to convey sewage to sanitary drainage system • Public Sewer • Sewer system maintain by Authority

29. Sanitary Services – Planning Requirements • To consult CBPU on connection to public sewer. Typically one connection. Large development may have more than one. Design flow calculation may require. • Provide last IC and connection point to Architect for their Development Control (DC) submission to CBPU • Design and submission of Internal house sewer is by M&E Engineer • Design and submission of minor sewer is by Structural Engineer

30. Sanitary Drainage System

31. Sanitary Drainage System Design parameters • Max. distance of branch line not exceed 20m (150mm dia.) or 10m (100 mm dia.) • Max. distance of main drain line between IC not exceed 50m (min 150mm dia.) • 1st IC at least 750mm depth • Last IC sited within 2.5m of the boundary • Main drain line between IC - straight run with constant gradient • 150mm dia. - 1 in 30 to 1 in 90 225mm dia. - 1 in 40 to 1 in 150 Min. velocity 0.9m/s, Max. velocity 2.4 m/s

32. Sanitary Drainage System • Nos. of connection into IC limited by physical size • Typically 4 branches to a 900 x 700mm IC • Max. 6 branches into 1350 x 700mm IC • First IC shall be vented unless serve discharge/vent stack of min. 100mm dia. • Condominium/Service Apt/Hotel - one discharge stack per toilet • Commercial/Office/Industrial - Individual stack for male & female toilet

33. Sanitary Drainage System Invert Level Calculation

34. Sanitary Drainage System How to determine IC Invert Level and Layout ? • Study the terrain to minimize the depth • Co-ordinate with structural ground beams, pile caps and drains where penetration is not allow • Co-ordinate with Architects on IC layout (no surprises) • Points to note: • TL of last IC should be higher than TL of Sewer MH • Main drain lines shall not sited within road and drainage reserve • Min. depth 2.4m if sited within planting strip/green buffer

35. Sanitary Drainage System • Case 1 • Ground top level is flat. IC depth are minimize by having the gentlest gradient of 1:90 slope

36. Sanitary Drainage System • Case 2 • Ground top level is sloping in the range of 1:30 to 1:90. to minimize the depth of IC, main drain line gradient should follow the gradient of the terrain

37. Sanitary Drainage System • Case 3 • Top level slopping in the gradient >1:30. depth of IC may be minimize by using tumbling bay or back drop at calculated interval. IC gradient should be 1:30 to avoid starting with a deep IC

38. Sanitary Plumbing Systems • Fully ventilated system for 6 storey or lower • Fully ventilated system for 7 storey or higher • Single stack residential up to 6 storey • Ventilated stack system for residential up to 25 storey

39. Sanitary Plumbing Systems • How does the venting system works? Allow building drains to flow freely by allowing air into the drain system, avoiding the vacuum and slow drainage issue. Imagine a full soda bottle with its cap off, turned upside down, the soda does not flow nicely out of the bottle. As some soda spills out, the spillage has to nearly stop to let some air into the bottle to fill the vacuum created by the soda leaving. Now perform the same experiment, but punch a hole in the bottom of your soda bottle just before you turn it upside down. Because air can easily enter the bottle the soda flows nicely out of the bottle mouth.

40. Sanitary Plumbing Systems • Why venting system is important? Allow sewer gases to be vented safely outdoors. Prevent sewer gases and foul smell flow back up into the building drain piping from sewer system. The plumbing vent system will carry these gases outside, usually above the building roof, where they are disposed-of safely and without leaving unpleasant, or possibly dangerous smells and gases inside the building. • Poor venting system Poor venting not just an annoyance, it can be unsafe since there is also the risk that the poorly-vented plumbing fixture will lose the water from its plumbing trap, then permitting sewer gases into the building.

41. Fully ventilated system for six-storey or lower

42. Fully ventilated system for seven-storey or higher

43. Single stack residential up to six-storey

44. Ventilated stack system for residential up to 25 storey

45. Sanitary Plumbing Systems • Sanitary shaft location preferable next to toilet/kitchen. Minimize horizontal pipe run. Typical size 600 x 300mm for 150mm SWS and 100mm VS. • Avoid sanitary pipe running above dry area (i.e. living, dining, bedroom) • Double slab is required if unavoidable. To consult QP and JD

46. Sanitary services Flow Rate and Pipe Sizing • Calculate discharge unit • Convert discharge loading unit to flow rate. • Pipe sizing based on flow rate.

47. Sanitary ServicesDischarging Unit

48. Sanitary Services-FromDU to flow rate

49. Sanitary Services Branch discharge pipe sizing Minimum waste pipe for commonly used sanitary appliance

50. Sanitary Services Vertical stack & vent stack sizing