The following set of instructions outline how to use the Studor web-based and Airflow Calculator Apps. The input fields are highlighted in pink for the web-based version and are white in the App.
- Select the system tab: either System I or II
- 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.
- Select frequency factor of the drainage system
- 5 – intermittent use, e.g. in dwelling, guesthouse, office
- 7 – frequent use, e.g. in hospital, school, restaurant, hotel
- 0 – congested use, e.g. in toilets and/or showers open to public
- 2 – special use, e.g. laboratory
Note: For high rise buildings we tend to always use the 0.7 factor as an added safety factor and to cover mixed usage of the building.
- Enter number of fixtures on a typical branch
- Enter the total number of each type of appliance, leaving as 0 (zero) if there are none.
- To calculate the number of Discharge Units (DU) on the App press “Calculate” or on the web-based Calculator press Enter or Tab.
- On the App the branch airflow requirement is the same as Qtot.
- On the web-based Calculator enter the continuous flow rate (Qc) and pumped water flow rate (Qp) if necessary (this facility is not available on the App). The branch airflow requirement will be updated accordingly.
Note: 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 water flow rate.
- Enter stack levels
- Enter the number of floors of typical branches connected to the stack. The stack airflow requirement will be updated accordingly.
Note: 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.
- Email results
- To email the calculation results to yourself, which includes the total number of recommended Studor AAVs, click “Email” (App) or “Email results” (web-based version).
The Studor Airflow Calculator is based on European Standard EN 23056-2 – 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 0.7 (70%) and are connected to a single stack.
Control of pressure in the discharge stack is achieved by used 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 the 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 is the design flowrate in a part of in the whole of the drainage system where sanitary appliances, 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.
The pipe capacity (see below) shall be at least the larger of:
a) the calculated waste water flowrate or total flowrate; or
b) the flowrate of the appliance with the largest discharge unit.
Need more assistance? Then please speak to a member of our technical team
For further assistance or information regarding the Studor Airflow Calculator or any other drainage matters, please feel free to get in touch with a member of our technical team at email@example.com.