Chapter 6 - Additional Information; Calibration & Bump Test - Honeywell Midas S2 User Manual

CHAPTER
6
ADDITIONAL INFORMATION
Learn from about strategic information related to the Midas S2 Detector.
6.1 Calibration & Bump Test
All Midas S2 sensor cartridges are pre-calibrated by Honeywell Analytics using traceable gas
standards and approved calibration methods to a proven ISO 9000 quality controlled
procedure. The Midas S2 sensor cartridge design is very robust and resistant to long term drift;
in fact in a normal operating environment it is possible to extend the calibration interval with
Midas S2 up to 24 months (subject to local requirements concerning calibrations). This design
feature is another element that supports Midas S2 as a long term cost effective gas detection
solution. Honeywell recommends frequent bump testing to confirm performance.
NOTE: It is the sole responsibility of each user to determine their own calibration and bump test
schedule based on their own safety assessments and understanding of local requirements.
Just before commissioning, each Midas S2 unit should be zero calibrated to ensure accuracy. It
is recommended that the unit be powered with the cartridge installed for at least 30 minutes
prior to conducting a zero calibration. A second zero calibration may be required after a 24 hour
period which is dependent on the site conditions. O2 sensors are not zero calibrated but should
be span gas calibrated. See the Gas Table for span gas calibration details. If the ambient
condition in the area the detector is monitoring experiences a long-term change, it is necessary
to perform a zero calibration to allow the unit to adjust to the new conditions.
NOTE: When performing a zero calibration, be sure that the area is free of the target gas and
interfering gases (refer to the cartridge data sheets for further details), as the presence of a
background gas will affect the ability for the detector to properly calibrate to the correct levels.
If the sample area cannot be verified to be free of the target gas or cross-sensitive gases, use a
cylinder of zero air to perform the calibration
Calibration of an electrochemical sensor cartridge is a relatively complex discipline to master
and it is possible that in less ideal field conditions the calibration can be far less accurate than
under laboratory conditions and therefore substantial inaccuracies can be introduced. In the
absence of any formal calibration policy by the end user, it is preferable to retain the original
factory calibration.
Care must be taken to ensure that the correct materials for an extractive application are
obtained from reputable suppliers and are of proven quality and composition. Inappropriate
calibration equipment will lead to under - or over-presenting the wrong concentration of gas to
the sensor cartridge during the calibration period. Likewise contaminated or inadequately
flushed tubing and other gas-wet surfaces can also introduce errors into the calibration
process. Only qualified, trained personnel should attempt to perform gas calibrations; contact
Midas S2 43 User Manual