The airflow calculator allows you to work out the branch and stack airflow requirement for your project.  Simply pick your system (I, II or III) based on the European Standard EN 12056-2 and fill in the relevant details that apply to your project in the fields below.  If you wish you can then email a copy of the results to yourself.

 

Please read the instructions carefully before using the calculator. You will find the calculator underneath the below instructions. 

 

1. First select the system tab (either I, II or III)

System I (50%) – For single discharge stack system with partly filled branch discharge pipes.  Designed with a filling degree of 0.5 (50%) with a single stack.

System II (70%) – For single discharge stack system with partly filled branch discharge pipes.  Designed with a filling degree of 0.7 (70%) with a single stack.

System III (100%) - For single discharge stack system with full bore branch discharge pipes.  Designed with a filling degree of 1.0 (100%) with a single stack.

 

2. Next select the frequency factor of the drainage system (drop down multi choice field)

0.5 - Intermittent use (For example in a single dwelling or a guesthouse or office)

0.7 - Frequent use (For example in a hospital, school, restaurant or hotel) We tend to always use this for high rise buildings as an added safety factor and to cover mixed usage of the building.

1.0 - Congested use (For example in toilets or showers open to the public)

1.2 - Special use (For example in a laboratory)

 

3. Enter the number of fixtures on a typical branch

Enter the total number of each type of appliance, leaving the units field as ‘0’ if there are none.  Then underneath the appliance list enter the continuous flow rate (QC) and pumped water flow rate (Qp) if necessary.  The branch airflow requirement (Qtot) will be updated accordingly.

Qtot = Total water flow rate requirement for the branch and should be less than the hydraulic capacity (Qmax) detailed in Table 7 of EN12056-2 (see below). This is the minimum branch pipe size for the given total flow rate.

 

 

4. Under Stack Calculation enter the number of floors of typical branches connected to the stack. The stack airflow requirements will be updated accordingly. QWW = total water flow rate requirement for the stack, and should be less than the hydraulic capacity (Qmax) detailed in Table 12 of EN12056-2 (see below) This is the minimum stack pipe size for the given total water flow rate.

 

 

5. If you would like to email the results to yourself, which includes the total number of recommended Terrain Pleura Vents click the ‘email results’ button.

 

EN 12056 SYSTEM I - Filling Degree of 0.5 (50%)
Single Discharge System with Secondary Ventilated System

Branch Frequency Factor (K)
ApplianceUnitsDU (l/s) Total DU
Wash basin0.5
0
Bidet0.5
0
Shower without plug0.6
0
Shower with plug0.8
0
Single urinal with cistern0.8
0
Urinal with flushing vlave0.5
0
Slab urinal0.2
0
Bath0.8
0
Kitchen sink0.8
0
Dishwasher (household)0.8
0
Washing machine 6kg0.8
0
Washing machine 12kg1.5
0
WC with 4.0 l cisternNANA NA
WC with 6.0 l cistern2
0
WC with 7.5 l cistern2
0
WC with 9.0 l cistern2.5
0
Floor Gully DN 500.8
0
Floor Gully DN 701.5
0
Floor Gully DN 1002.0
0
BranchTotal DU
0
Total DU required
Qww
0.00
Qww = (l/s)
Qc Continuous flow rate (l/s)
Qp Pumped water flow rate (l/s)
Qtot
0.00
Total water flow rate (l/s)
Branch Airflow requirement
0.00
SYS I: 1X Qtot
Terrain Pleura 50 Valve
7.5
l/s

 

Stack CalculationLevels DU (l/s)
Stack
0.00
Total
0.00
Qww = (l/s)
Stack Airflow requirement
0.00
l/s SYS I: 8X Qtot
     
The Terrain SystemAirflow (l/s)UnitsTotalInstall Location
Terrain Pleura 100 Valve321
0
Top of stack
Terrain Pleura 50 Valve7.5
0
From each branch
0
l/s (total air from Terrain System)
Email Results

EN 12056 SYSTEM II - Filling Degree of 0.7 (70%)
Single Discharge System with Secondary Ventilated System

Branch Frequency Factor (K)
ApplianceUnitsDU (l/s) Total DU
Wash basin0.3
0
Bidet0.3
0
Shower without plug0.4
0
Shower with plug0.5
0
Single urinal with cistern0.5
0
Urinal with flushing vlave0.3
0
Slab urinal0.2
0
Bath0.6
0
Kitchen sink0.6
0
Dishwasher (household)0.6
0
Washing machine 6kg0.6
0
Washing machine 12kg1.2
0
WC with 4.0 l cistern1.8
0
WC with 6.0 l cistern1.8
0
WC with 7.5 l cistern1.8
0
WC with 9.0 l cistern2
0
Floor Gully DN 500.9
0
Floor Gully DN 700.9
0
Floor Gully DN 1001.2
0
BranchTotal DU
0
Total DU required
Qww
0.00
Qww = (l/s)
Qc Continuous flow rate (l/s)
Qp Pumped water flow rate (l/s)
Qtot
0.00
Total water flow rate
Branch Airflow requirement
0.00
SYS II: 2X Qtot
Terrain Pleura 50 Valve
7.5
l/s

 

Stack CalculationLevels DU (l/s)
Stack
0.00
Total
0.00
Qww = (l/s)
Stack Airflow requirement
0.00
l/s SYS II: 8X Qtot
     
The Terrain SystemAirflow (l/s)UnitsTotalInstall Location
Terrain Pleura 100 Valve321
0
Top of stack
Terrain Pleura 50 Valve7.5
0
From each branch
0
l/s (total air from Terrain System)
Email Results

EN 12056 SYSTEM III - Filling Degree of 1.0 (100%)
Single Discharge System with Secondary Ventilated System

Branch Frequency Factor (K)
ApplianceUnitsDU (l/s) Total DU
Wash basin0.3
0
Bidet0.3
0
Shower without plug0.4
0
Shower with plug1.3
0
Single urinal with cistern0.4
0
Urinal with flushing vlave0.3
0
Slab urinal0.2
0
Bath1.3
0
Kitchen sink1.3
0
Dishwasher (household)0.2
0
Washing machine 6kg0.6
0
Washing machine 12kg1.2
0
WC with 4.0 l cisternNANA NA
WC with 6.0 l cistern1.7
0
WC with 7.5 l cistern1.8
0
WC with 9.0 l cistern2.0
0
Floor Gully DN 500.9
0
Floor Gully DN 700.9
0
Floor Gully DN 1001.2
0
BranchTotal DU
0
Total DU required
Qww
0.00
Qww = (l/s)
Qc Continuous flow rate (l/s)
Qp Pumped water flow rate (l/s)
Qtot
0.00
Total water flow rate (l/s)
Branch Airflow requirement
0.00
SYS III: 1X Qtot
Terrain Pleura 50 Valve
7.5
l/s

 

Stack CalculationLevels DU (l/s)
Stack
0.00
Total
0.00
Qww = (l/s)
Stack Airflow requirement
0.00
l/s SYS I: 8X Qtot
     
The Terrain SystemAirflow (l/s)UnitsTotalInstall Location
Terrain Pleura 100 Valve321
0
Top of stack
Terrain Pleura 50 Valve7.5
0
From each branch
0
l/s (total air from Terrain System)
Email Results

Additional information

NB This airflow calculator is designed to provide an indication of branch and stack airflow requirements for your project.  For detailed system requirements please contact our Technical Support team on +44 (0) 1622 795412  or email commercialenquiries@polypipe.com

 

This Airflow Calculator is based on European Standard EN12056-2 – Gravity Drainage Systems Inside Buildings.

Sanitary appliances are connected to small bore branch discharge pipes.  The small bore branch discharge pipes are designed with a filling degree of 0.5 (50%) for system I, 0.7 (70%) for system II and 1.0 (100%) for system III and are connected to a single stack.

Control of pressure in the discharge stack is achieved by use of separate ventilating stacks and/or secondary branch ventilating pipes in connection with stack vent. Alternatively, Air Admittance Valves (AAVs) may be used.

Control of pressure in the discharge branch is achieved by ventilation of the discharge branch.  Alternatively, AAVs may be used.

 

Waste water flowrate

The total waste water flowrate is the expected flowrate of waste water in a part or in the whole drainage system where only domestic sanitary appliances are connected to the system.  This is calculated as a frequency factor (K) x the square root of the sum of the discharge units.

 

 

 

Discharge units (DUs) of a variety of sanitary appliances are given values for the purpose of calculation and are not related to discharge rates of sanitary appliances quoted in the standard.

 

Total flowrate

Total flowrate is the design flowrate in a part of, or in the whole of, the drainage system where sanitary appliances with continuous flow and/or waste pumps are connected to the system.

Continuous flows and pump discharge rates shall be added to the waste water flowrate without any reduction.

The total flowrate is calculated by adding together the waste water flowrate, the continuous flowrate and the pumped water flowrate.

 

Calculation rules

The pipe capacity (See table 11 below) shall be at least the larger of:

  1. The calculated waste water flowrate or total flowrate: or
  2. The flowrate of the appliance with the largest discharge unit.