Retrotec USACE - Manual (Page 322)

F28 ENERGY & PROCESS ASSESSMENT PROTOCOL
suspended ceiling can withstand without tearing it down in depressurize mode
or blowing the tiles out in pressurize mode.
A sensitivity analysis was done on the sixth fl oor of an offi ce building. Data
was gathered in no-wind conditions and in conditions with a 10 to 15 mph wind
blowing. Six test points were taken per test except for tests in both directions
where six points were taken in each direction. Results were measured in L/s at
75 Pa. Twenty-three tests were performed under low wind conditions and an-
other 26 tests were performed under windy conditions. All low wind tests were
averaged and that average was used as the true result. The deviation result
shown in Table 4 was the average deviation from the true result. The “Error
range” shows the maximum and minimum error values measured from true.
TABLE F4. RESULTS OF SENSITIVITY ANALYSIS OF TEST DIRECTION AND
WIND CONDITIONS ON TEST ERROR RANGE
No wind Windy
Direction Pressure range
Deviation
(%)
Error range
(%)
Deviation
(%)
Error range
(%)
Depressurize with
Bias –60 to –12.5 Pa 2 –2.5 to + 1.5 17 –24 to –10
Depressurize with
Bias –50 to –25 Pa 2 –2.5 to + 1.5 10 –13 to –6
Depressurize with
Bias –75 to –50 Pa 1.4 –2 to + 0.5 5.3 –7 to –3
Both Directions
with Bias +/–75 to +/–50 Pa 1.1 –1.1 to + 1.5 4.9 –6 to –3
Both Directions
without Bias +/–75 to +/–50 Pa 1.5 –1.8 to + 1.5 3 –6 to –1
Both Directions
without Bias +/–50 to +/–25 Pa 1.5 –1.8 to + 1.9 4.9 –8 to –3
F.12.2 Observations
Under windy conditions, the classic ASTM test procedure (measuring 1.
the before and after bias pressure and only testing in one direction from
60 to 12.5 Pa) produced the most unacceptable results. Variations in fl ow
readings from 1 minute to the next, even with time averaging in place,
varied as much as 25 percent for one reading.
If testing was to be completed in only one direction, reasonable results
2.
could be achieved by measuring the before and after bias pressures and
testing at higher test pressures, from 75 to 50 Pa.
Testing in both directions and averaging the results always yielded results
3.
with less deviation than only testing in one direction.
The best results were obtained from testing in both directions
4. with-
out taking the bias pressure into account. It was observed that any bias