Retrotec Multi-Fan Blower Door - Manual (Page 9)

Page 9 of 37
©Retrotec Inc. 2015
2.2 Zone-to-Zone Leakage Test
Zone-to-Zone Leakage tests are the only way to measure the leakage through a particular surface, such
as a partition wall between two apartments, or the leakage from a hallway into an apartment.
Zone to zone leakage is more complicated than total zone leakage – it involves pressure neutralization
between two zones. How to set up your fans is based on the fundamental concept of Pressure
Neutralization, described in the next section.
2.2.1. Pressure Neutralization
Flow is caused by a pressure differential across a hole. The idea behind Pressure Neutralization
(sometimes confusingly called “guarded testing” even though nothing is actually guarded) is that if
you pressurize both sides of any hole to the same pressure, there will be no flow (hence, no leakage
measured) through the hole since there is no pressure differential. The magnitude of this pressure
can be large or small, but as long as the pressure on both sides is the same, there will be no flow.
2.2.2. Measure Leakage between floors using pressure neutralization
The procedure below describes how leakage between floors of a high rise building is measured by
Pressure Neutralization.
To measure the leakage between the 10th floor and
the 9th floor, you would set up Door Fans on both
floors.
1. Pressurizing only the 10th floor, the gauge on the
10th floor will be measuring the flow (or leakage)
across all barriers of that floor.
In Figure 5, 1000 CFM is measured as the flow
across all barriers of the 10th floor.
Figure 5: Measure the flow across all barriers on the top
floor
2. Pressurizing both 10th and 9th floors, the gauge
on the 10th floor will now be measuring the flow
(or leakage) across all barriers except the slab
between floors - there is no flow between the
10th and 9th floor due to Pressure Neutralization.
In Figure 6, 800 CFM was measured as the flow;
This means that the flow between the 10th and
9th floor must be 200 CFM, by subtraction from
the result of step 1.
1000 CFM – 800 CFM = 200 CFM
Figure 6: Measure the flow from the top floors combined
The order of steps 1 and 2 can be interchanged. To test the leakage of the other floors, you would
move the Door Fan from the 10th floor to the 8th floor and repeat the procedure.