Manual

14
Setting or Verifying Flow Rate
When performing multiple-tube sampling using an adjustable
low fl ow holder (dual, tri, or quad), ensure the regulator has been
activated and the pump fl ow rate is set at 1.5 L/min. The maximum
fl ow rate through any one tube is 500 ml/min*. Calculate the sum
of all tube fl ow rates. If the sum is ≤1000 ml/min, proceed with
calibration and sampling without any further adjustment to the
pump fl ow rate. If the sum is >1000 ml/min, set the pump fl ow rate
15% higher than the sum of tube fl ow rates.
* Back pressure across some sample tubes can be higher than average. In
these instances, the maximum fl ow rate of 500 ml/min per tube may not be
achieved.
Before use, allow pump to equilibrate after moving it from one
temperature extreme to another.
Ensure pump has run for five minutes before proceeding with
calibration.
Ensure the pump is set for low fl ow. See Activating the Regulator,
page 9.
Connect the adjustable low flow holder (Figure 4, page 13)
to the pump intake (Figure 2, #9) using 1/4-inch Tygon tubing.
Insert an opened sorbent tube into each rubber sleeve of the low
fl ow holder (Figure 4, #3 and 4) with the arrow on the tube pointing
toward the holder.
If sampling with fewer tubes than number of ports, insert
unopened sorbent tubes in the empty ports to seal them.
Note the fl ow rates specifi ed by each sampling method and
add them together. If the sum is ≤1000 ml/min, proceed to
the next step. If the sum is >1000 ml/min, multiply the total
tube fl ow rate by 1.15 and set the pump for that fl ow rate.
Connect a calibrator to the exposed end of a sorbent tube,
loosen the brass fl ow adjust screw on the low fl ow holder, and
activate the pump by pressing Flow and Battery Check.
Connect holder to
pump intake and tube
inlet to calibrator.
continued on page 15
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