SKC 224-52 AirChek 52 - Manual (Page 15)

13
Setting or Verifying Flow Rate - Multiple Tube
When performing multiple-tube sampling using an
adjustable low fl ow holder (dual, tri, or quad), ensure 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.
Set pump fl ow rate to 1.5 L/min. Connect a constant pressure
controller (CPC) (Figure 2, page 10) to the pump intake
(Figure 2, #1) using 1/4-inch Tygon tubing.
Using 1/4-inch tubing, connect the intake of a CPC (Figure
2, #3) to the outlet of a multiple-tube adjustable low fl ow
holder (Figure 3, #7).
Insert an opened sorbent tube into each rubber sleeve of the
low fl ow holder (Figure 3, #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 CPC to pump
intake, holder to CPC,
and tube inlet to
calibrator.
continued on page 14
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