PGA 3510 Operations Manual
Super Systems Inc.
Page 17 of 42
Two types of calibrations can be performed on the NDIR sensor; Zero and Span. The Zero calibration
should be performed with a gas that has none of the measured gases in it. Ideally this would be pure
Nitrogen or Argon. The concentration of the Span calibration gas should closely resemble the gas that is
being measured. For a heat treating application measuring endothermic gas, the ideal composition
would be:
•
CO: 20%
•
CO
2
: 0.5%
•
CH
4
: 5.0%
•
H
2
: 40%
•
N
2
: Balance
Since the accuracy of the calibration gas directly influences the resulting accuracy of the instrument, the
highest possible accuracy grade should be obtained. Some gas suppliers refer to this as a “Certified
Primary Standard”. The high degree of accuracy is not required to obtain nominal values that exactly
match the values shown above. The accuracy is required to know the exact composition of the gas in the
cylinder. The actual composition will be shown on the bottle when it is delivered.
When flowing calibration gas is into the analyzer, turn the pump off. The amount of flow from the gas
cylinder should be approximately 1.5 SCFH at no pressure. The gas cylinders will be under high
pressure, so it is recommended that a two stage regulator with a low pressure secondary stage be used.
It is good practice to begin the flow of gas before attaching the calibration gas to the instrument. This will
prevent any high pressure bursts from entering the instrument.
Calibration gases can be obtained from Super Systems, however they can also be obtained from any
supplier of custom gases.
Hydrogen Cell Note:
It is recommended that the instrument be turned on for three hours prior to performing an H
2
calibration.
Performing a Zero Calibration
From the Sensor Calibration screen, be sure that the button at the upper left of the instrument is
selecting Zero Calibration and not Span Calibration.