Sanitary and sewerage piping work

Discharge unit

• When the number and type of sanitary appliances are known , the diameter and gradient of a foul water drain may be found by a discharge unit method . 
• Each sanitary appliance is given a discharge unit value , which represents the rate of discharge , capactiy and frequency of use of the appliance . 
• The sum of a ll the sidcharge units of the sanitray appliances connected to the stack is found and the BS 5572 gves a list of discharge units allowed on vertical stacks and horizontal branches . 
• Example 1

E-5-a. Given a five sotrey office building with 6W.C.s , 8 wash basins , 2 sins on each floor , determine the sizes of the main waste and soil stack .