Retrotec FanTestic (ATTMA) - Manual (Page 27)

rev-2014-10-27
Page 27 of 58
©Retrotec Inc. 2011-2014
Data readings from each fan are specific to the range configuration installed on the fan when the
pressure or flow is read from the gauge. A Fan Pressure Line must be included in the set for each
fan/range combination used during the test (if ranges have to be changed during a test to reach the
required induced pressure).
If fan pressure (or flow values) are too low to be in the valid calibrated region of the fan for the induced
pressure point being measured, the digits will turn red at the row/column of the fan pressure line
affected.
Test standards also require recording the state of the building pressure as it is without any fan running.
This is variously called baseline, or bias pressure. Space is provided in the data set for readings taken
when the fan is not running before the test commences. If the Standard requires measuring the
baseline after the test is complete, there is space for that too.
Pressurization/depressurization depends on the location of the blue pressure pickup on the gauge with
respect to the building, since building induced pressure is measured between the red and blue
connections, and the red tube always goes through the panel. The location of the operator (blue pickup
on the gauge) as well as the sign (plus or minus) of the induced pressures are thus used to choose the
label on the data set – “Pressurization Set” or “Depressurization Set”.