{"id":38,"date":"2022-06-20T13:41:24","date_gmt":"2022-06-20T17:41:24","guid":{"rendered":"https:\/\/opentextbc.ca\/plumbing3a\/chapter\/size-pipe-for-sewers\/"},"modified":"2022-08-17T11:45:11","modified_gmt":"2022-08-17T15:45:11","slug":"size-pipe-for-sewers","status":"publish","type":"chapter","link":"https:\/\/opentextbc.ca\/plumbing3a\/chapter\/size-pipe-for-sewers\/","title":{"raw":"Learning Task 2","rendered":"Learning Task 2"},"content":{"raw":"The following explanations are a synopsis of the sizing steps for sanitary, storm and combined sewers. These steps were originally covered in greater detail in Learning Modules D-1: \u201cInstall Sanitary Drain, Waste and Vent Systems\u201d and D-3: \u201cInstall Storm Drainage Systems\u201d of the BC Apprenticeship Learning Guides for Plumber.\n

Code Requirements for Sewerage Systems<\/h1>\nMost provinces and territories in Canada have adopted the National Plumbing Code of Canada (NPC) as the accepted code for that jurisdiction. Provinces such as British Columbia and Ontario have chosen to create their own code by using the NPC as the base document and adding supplements to satisfy regional needs. For the purposes of explanations within this literature we will reference tables and clauses from the NPC; the same tables and clauses can be found in the BCPC, however the prefix \u201c2\u201d will be replaced by the prefix \u201c7\u201d where the BCPC is used.\n\nBoth codes have established a minimum acceptable standard for the design and installation of sanitary, storm and combined drainage systems on private property. The size of sewer is dependent on the hydraulic load on the pipe, the grade on the pipe and the Code table used for sizing. It is important to note that the NPC has no application on public property, although its clauses and tables can be used as guidelines. All aspects of sewer installations on public property are determined by engineers and their \u201cgood engineering practices\u201d.\n

Sanitary Building Sewer Sizing<\/h2>\nSanitary sewers systems use fixture units (FU) to determine the hydraulic load imposed on the sewer system by the upstream fixtures or appurtenances. \u00a0A fixture unit is not a flow rate unit but rather a design factor based on the rate of discharge, time of operation and frequency of use of a fixture. In original calculations arrived at by PDI (Plumbing and Drainage Institute) a fixture unit was equal to one cubic foot of water drained through a 1 \u00bc\u201d OD pipe over one minute.\n\nThe fixture unit values of individual fixtures can be found in NPC tables 2.4.9.3 and 2.4.10.2.\n\nThe sizing procedure for a sanitary sewer is fairly simple:\n
    \n \t
  1. Determine the total number of fixture units from fixtures found in tables 2.4.9.3 and 2.4.10.2<\/li>\n \t
  2. Add the flow from any semi-continuous or continuous flow appurtenances draining into it. These loads are normally expressed in L\/sec, so they have to be converted into FU by applying the conversion number given in 2.4.10.3 (1) of the NPC, which is 31.7 fixture units per litre\/second<\/strong>.<\/li>\n \t
  3. Once a total flow rate of fixture units has been calculated, it is applied to Table 2.4.10.6.-C to establish the minimum size of sanitary building sewer required at the chosen grade.<\/li>\n<\/ol>\nNote: See the explanation and illustrations in A-2.4.10 of the NPC for an example of these sizing methods.\n\nAdditional loads to be added when sizing a storm drainage system include:\n