Form 37714 Rev 2002
Page 6 of 13
Low Flow Applications (Cont)
Using a CPC and Dual, Tri, or Quad Adjustable Low Flow Tube Holder (Figure 3)
Set/Calibrate Flow Rate for Multiple Tubes
• Requires Constant Pressure Controller (CPC) and Adjustable Low Flow Tube Holder (see Accessories). The low flow tube holder used with CPC
allows up to four tube samples to be taken simultaneously, each at different flow rates if desired.
• Allow pump to equilibrate after moving it from one temperature extreme to another.
• Charge pump battery completely before calibration and sampling.
• Calibrate/verify pump flow rate before and after each sampling operation using the tube holder and pump to be used for sampling.
• Set the flow rate through the pump first and then calibrate the flow rate through each representative sorbent tube.
Pump Flow Rate
Follow these important steps before proceeding.
1. Ensure that the battery is fully charged and that the pump has run for 5 minutes before calibrating. Leave pump running.
2. Prepare a calibrator
(see calibrator instructions)
. Using flexible tubing, connect the calibrator outlet (suction port) to the pump inlet.
3. Calculate the sum of all tube flow rates. The maximum flow rate through any one tube is 500 ml/min.*
a. If the sum is
≤
1000 ml/min, set the pump flow rate to 1.5 L/min.
b. If the sum is > 1000 ml/min, multiply that number by 0.15 and total the two numbers. Set the pump flow rate for the resulting
new sum. (
Example:
Sampling with three sorbent tubes, each with a flow rate of 500 ml/min.* The sum of the tube flow rates is
calculated as 3 x 500 = 1500. Determining a 15% higher flow rate is calculated as 1500 x 0.15 = 225. Calculating the final pump
flow setting would be 1500 + 225 = 1725 ml/min.)
* Back pressure across some sample tubes can be higher than average. In these instances, the maximum flow rate of 500 ml/min per tube may not
be achieved.
4. Using a small screwdriver, turn the flow adjustment screw on top of the pump
(Figure 1)
(
clockwise
to increase flow or
counterclockwise
to decrease flow) until the calibrator indicates the required flow rate.
5. Remove tubing from the pump inlet and calibrator outlet.
Figure 3.
Quad Adjustable Low Flow Tube Holder
Top view of flow
adjust screws
Anti-tamper cover
Low flow holder outlet
Sorbent sample tube
Rubber sleeve
Clothing clip
Flow adjust screws
Protective cover
