Calibration
5.1 Overview
This section of the manual describes the calibration process and
issues relating to calibration. Next to sample system problems, calibration
is the single most important item relating to the proper performance of
your analyzer. A properly calibrated instrument will produce accurate and
repeatable measurements of the gas of interest across the entire instrument
range.
To calibrate the instrument, you will need:
•
A zero gas (preferably nitrogen)
•
A span gas which contains the gas of interest at a concentration
greater than 50% of the full instrument range (preferably 80%)
• A means of appropriately switching from sample gas to
calibration gas (2 solenoid valves if using the automatic
calibration feature).
5.2 Typical Sample System
Two typical piping diagrams for the IR7000 are shown in Figure 5-1.
The explosion proof models can use a similar sample system and can
control up to 3 solenoid valves. The sample system for the explosion proof
models is housed separately in an explosion proof housing with the
electronics and controls remotely located in the control section up to 300
feet away. A specific application is shown in Figure 3-3.
Either of these configurations allows the user to control the input
stream to the analyzer with only 2 3-way valves. When flowing calibration
gas, some means must be provided for bringing the zero or span gas to the
same pressure and flowrate as the sample gas to avoid any flow induced
variables which could affect the calibration. It is highly recommended that
the calibration gas sources use a regulator and flow control device (inline
needle valve or flow meter with integral needle valve).
Figure 5-1A & B: Flow Diagram for Manual Calibration