Tisch Environmental TE-5170DV, Operation Manual

Page: 22 / 40

TE-5170DV-BL 22 Operations Manual
Once these actual flow rates have been determined for each of the five run points, they are recorded in
the column titled Qa, and are represented in cubic meters per minute. EPA guidelines state that at least
three of these calibrator flow rates should be between 1.1 to 1.7 m3/min (39 to 60 CFM). This is the
acceptable operating flow rate range of the sampler. If this condition is not met, the sampler should be
recalibrated. An air leak in the calibration system may be the source of this problem. In some cases, a
filter may have to be in place during the calibration to meet this condition.
The sampler H
2
O readings need to be converted to mm Hg and recorded in the column titled Pf. This is
done using the following equation:
Pf = 25.4 (in. H
2
O/13.6)
where: Pf is recorded in mm Hg
in. H
2
O = sampler side pressure reading during calibration.
Po/Pa is calculated next. This is used to locate the sampler calibration air flows found in the Look Up
Table. This is done using the following equation:
Po/Pa = 1 - Pf/Pa
where: Pa = ambient barometric pressure during calibration, mm Hg.
Using Po/Pa and the ambient temperature during the calibration, consult the Look Up Table to find the
actual flow rate. Record these flows in the column titled Look Up.
Calculate the percent difference between the calibrator flow rates and the sampler flow rates using the
following equation:
% Diff. = (Look Up Flow - Qa)/Qa * 100
where: Look Up Flow = Flow found in Look Up Table, m3/min
Qa = orifice flow during calibration, m3/min.
The EPA guidelines state that the percent difference should be or - 3 or 4%. If they are greater
than this a leak may have been present during calibration and the sampler should be recalibrated.
Example Calculations