
66
Standard Operating Procedures (SOPs)
readings to verify the actual volumetric or standardized flow rates.
5.2
Capture an averaged reading. When live flow readings are unstable,
on account of pump or flow controller
oscillations, take an averaged reading. Select
START AVG at the top right of the live display in
Standard Mode. The averages are updated live as
the measurement runs. While the measurement
is running, the timer displays the remaining
measurement time at the bottom right of the
screen.
»
The screen will display Final Avg at the top
when the averaged measurement has finished.
Select INST/MENU to resume live readings.
Note: The averaging function records averaged readings of all flow
data, including temperature and pressure readings.
5.3
Verification or audit: Compare the sampler and FP-25 readings.
Is the sampler’s displayed actual volumetric or standardized flow reading
within 2% of the flow rate displayed by the FP-25?
» If yes, flow verification is complete.
» If no, calibrate the sampler.
5.4
Calibration: Enter the FP-25 flow value into the sampler for each
calibration point. Many air samplers use a 3-point flow calibration with
readings at the nominal flow rate (
e.g.
16.7 lpm), 10% below the nominal
rate (
e.g.
15.0 lpm for a 16.7 lpm sampler) and 10% above the nominal rate
(
e.g.
18.4 lpm for a 16.7 lpm sampler). Some require 5 calibration points.
5.5
If you are auditing a SASS or SuperSASS, repeat Step 2.3 and all of
Steps 4 and 5 of this procedure for each canister you are verifying.
5.6
Record your data.
6. Tare the FP-25 before calibrating the next sampler. Ensure that no
air is flowing through the device, and one end is open to atmosphere. When
ready, select MENU > TARE.
LPM
Probe
Vol Flow Avg
+16.723
Final Avg
MENU
+15.457
SLPM
+16.723
LPM
INSTNT
DATA
#C
+24.38
BARO
+704.0
Verifying Flow Rates in Standard Mode