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There is a need for a faster and easier way to find pipe diameter in gravity flow drainage pipe sizing when pipe % filled and flow design criteria are given. In BS EN 12056-2, sanitary drainage pipe shall be designed with a filling degree of 50% for System I, 70% for System II and 100% for System III.

The traditional way of finding pipe diameter is to use various charts. This process is too tedious and time consuming. Thus this gravity flow drainage pipe sizing software is specially designed in a simple yet effective way to find pipe diameter.

Built-in features:

• calculation in imperial or metric system via the selection of flow units (l/s, m3/s, gpm and ft3/s) for gravity flow drainage pipe sizing.

• find pipe diameter option for a given pipe % filled and flow criteria. 

• find pipe % filled option for a given pipe diameter and flow criteria.

• pipe flow full and partial capacities for a given/selected pipe diameter.

• calculate sanitary waste discharge unit (DU) flowrate as per EN 12056 Standard.

• find vertical stack pipe size as per EN 12056 Standard.

The popular Manning formula (see Wikipedia) for gravity flow hydraulic design is used to do the tedious hydraulic calculations. Iterative approximation methods have been used to find some solutions.

Design & Check Exercise 1: Determine Pipe Size for a Given Waste Discharge Flow From A Building . 

Design conditions: 

Waste discharge flow = 550 gpm

Degree of pipe filled = 50%

Pipe gradient = 1: 100 (i.e. Slope = 1%)

Pipe material = PVC (Manning coeff. = 0.009)

Answers:

Pipe diameter = 10 inch

Actual pipe % filled = 43.2

Flow depth = 4.32 inch

Flow area = 0.2256 ft2

Flow velocity = 5.4 ft/s

Design & Check Exercise 2: Determine Pipe % Filled for a Given Pipe Diameter . 

Design conditions: 

Waste discharge flow =50 l/s

Pipe diameter = 225 mm

Pipe gradient = 1: 90 (i.e. Slope = 1.11%)

Pipe material = Vetrified C lay (Manning coeff. = 0.013)

Answers:

Pipe % filled = 88.3

Flow depth = 198.76 mm

Flow area = 0.04 m2

Flow Velocity = 1.35 m/s

Final Thought: I thought this will provide solutions to meet your deliverables at anytime. 

Note: 

(1) For Android OS: see aPipeSizer.

(2) For classic water pipe sizing with gravity-fed flow, see Classic Water PiperSizer (Windows OS).