Calibration Procedure
 
testo 350 M/XL
 
Calibration of Gas Sensors
 
! CAUTION !
• Observe safety regulation/accident prevention regulations
when handling test gases.
 
• Use test gases in well ventilated room only.
 
Note:
• Calibration can only be performed with calibration gas of a known composition
and concentration. Gas that has exceeded its certification date should not be used.
 
• For most accurate results, the value of the calibration gas should be between
75% to 125% of expected value. Calibrations below 50% of the expected stack
gas concentration are suspect because of multiplication of errors.
 
Required equipment:
Calibration gas, non-reactive regulators, non-reactive/non-absorbing tubing, a by-pass
vent for excess calibration gas, flow regulating needle valve.
 

Stainless Steel Flow Controlled
Regulator with Overflow Vent

 
Calibration Kit With Regulator

Click here for more information about portable calibration gas kits.
 
! CAUTION !
DO NOT PRESSURIZE THE ANALYZER GREATER THAN 12" H2O (0.5 PSI)
WITH CALIBRATION GAS AS FAULTY READINGS AND DAMAGE MAY OCCUR.
USE A BYPASS VENT.
 
Note:
• Hydrocarbons gas should be in a carrier of O2 to facilitate calibration.
 
• Gases like NO2 and SO2 should only be used with non-reactive,
non-absorbent materials such as stainless steel, Teflon and C-Flex.
 
• Use single component gases to eliminate and/or identify cross interference.
 
• Calibration time should not need to exceed 5 minutes per gas exposure
to reach stability
 

 
 

 

Calibration Procedure
 
Preparation
 
1. Ensure the analyzer is fully charged or operating on AC current
2. Ensure the ambient air is free from background gas contaminants.
 
Warm-up
 
3. Start analyzer and operate pump for 15 minutes to purge residual gases from
sensors and to fully achieve operating stability
 
4. Zero the analyzer by pressing the function key
"Zero" (here the second on the left).
 
5. Press to enter the menu.
 
6. Press to highlight "Sensors" and press
 
7. Highlight "Calibrate" and press
 
8. Select the sensor to calibrate with and
(here CO) and press to accept.
 
9. Input the indicated value of the calibration gas
(e.g. 100) Connect to calibration gas
 
10. Connect the sample probe to the calibration apparatus.
11. Ensure the needle valve to the calibration gas is closed.
12. Press the "Start" function key
 
Note: The total calibration gas flow will be approximately 2 liters/minute. 1 liter/minute
to the analyzer; less than 1 liter/minute vented to assure adequate supply.
 
Adjust gas flow
 
13. Start the flow of the calibration gas to the analyzer by adjusting the needle valve.
14. Carefully adjust the flow to provide 1-2 liters/minute flow through the
bypass vent.
15. When the sensor reading indicates a change, time the process for 3-5 minutes
 
16. During the calibration this screen appears
and shows the values.
 
Note: Accept values At the end of the 3-5 minutes, press the "OK" function key to
adjust the sensor and to save the values into the memory. Escape will not calibrate
(adjust) the sensor. Memory will save the values but not calibrate (adjust) the sensor.
 
Prepare to calibrate other sensors
 
17. Purge the analyzer on fresh air for 5 minutes before beginning the next gas
 
Printing calibration data
 
Note: If there is no calibration data in the sensor (e.g. sensors with a manufacturing
date before January 2003) dashes are printed instead of the target and actual values.
Only the serial number and date of adjustment are printed.