PROGRAMMING
4-9
4.4.2
Span Calibration
This procedure determines the second point of the sensor
calibration curve for the sensor. A cylinder of standard
reference gas (span gas) fitted with a 500 cc/min. flow-
limiting regulator or a flow-matching regulator is the
simplest way to perform this procedure. Choose the 500
cc/min. regulator only if the flow rate matches or slightly
exceeds the flow rate of the instrument pump .
Alternatively, the span gas can first be filled into a Tedlar
Bag, or delivered through a demand-flow regulator.
Connect the calibration adapter to the inlet port of the
MiniRAE 2000 Monitor, and connect the tubing to the
regulator or Tedlar bag.
Another alternative is to use a regulator with >500 cc/min
flow but allow the excess flow to escape through a T or an
open tube. In the latter method, the span gas flows out
through an open tube slightly wider than the probe, and
the probe is inserted into the calibration tube.
Before executing a span calibration, make sure the span
value has been set correctly (see next sub-menu).
1.
Make sure the monitor is connected to one of the span
gas sources described above.
2.
Press the
[Y/+]
key at the “Span Cal?” to start the
calibration. The display shows the gas name and the
span value of the corresponding gas.
3.
The display shows “Apply gas now!” Turn on the
valve of the span gas supply.
