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H25-IR Calibration
Instruction 3015-4342 25
3.4 CAL Factor
The factory default CAL Factor of 1.000 will provide the level of accuracy as stated in Section 7
Specifications for all gases.
The CAL Factor can be changed for the following two reasons:
• Allow the instrument’s internal leak source to be used to calibrate the instrument,
regardless of the gas being measured
• Improve the accuracy of ppm measurements
Leak-rate accuracy can be maintained by periodically calibrating the instrument on the gas being
measured. If the instrument’s internal calibration gas is the same as the gas being measured, then it is a
simple matter of calibrating the instrument using the internal leak source. When measuring a gas that is
not the same as the instrument’s internal calibration gas, then there are two options for maintaining
accuracy. The instrument can either be calibrated using an external leak source, or the CAL Factor can be
adjusted to make the internal leak source simulate the gas being measured as described in Section 3.4.1.
The CAL Factor can also be used to improve the accuracy of ppm measurements as described in
Section 3.4.2.
3.4.1 Simulating Other Internal Leak Source Gas Types
Using the CAL Factor
When measuring the leak rate of a gas that is not the same as the instrument’s internal calibration gas,
the CAL Factor can be adjusted make the instrument’s internal calibration gas simulate the gas being
measured. This allows the operator to calibrate the instrument using the internal leak source, regardless
of the gas contained in the leak source. Note that this procedure is not necessary for single-gas
instruments.
Material Required:
• Calibrated External Leak Source set up for 5 to 10 times the leak rate
that the instrument is expected to detect
IMPORTANT! Remember that the accuracy will not be better than that of the
external leak source used for calibration.
Procedure:
1. Turn ON the instrument and allow it to warm up for 30 minutes before proceeding.
2. Program the instrument for the Gas Type contained in the external leak source (refer to Section
2.4.1 Gas Type).
3. Verify that the current CAL Factor is set to 1.000 by selecting the Main Menu > CAL DATA > CAL
FACTOR function. If necessary, reset the CAL Factor to 1.000. Refer to Section 3.4.3 Adjusting the
CAL Factor.
4. Perform an internal calibration in the normal way using the internal leak source (refer to Section
3.2 Internal Calibration). Note that it doesn’t matter that the gas in the internal leak source
doesn't match the Gas Type entered in Step 2.
5. Press the MODE key to place the instrument into its Measure mode.
6. Measure the leak rate of the external leak source and record the displayed reading.