Geotech G110 - Calibration; User Calibration; Calibration Gases; Calibration Set-Up

Page 30 of 48
Operating Manual
www.geotechuk.com
OMG100N Iss.02
© QED Environmental Systems Ltd.
G 1 0 0 R A N G E
CALIBRATION
User Calibration
The G100 range of instruments is fully calibrated during manufacture and when returned for service.
However, to improve accuracy between services a user/field calibration can be performed.
This section sets out the correct procedures to achieve an accurate user calibration.
Note: If the calibration is completed incorrectly it may decrease the accuracy of the instrument.
Two important terms that are used within this section are “Zero” and “Span”.
Zero: The point at which the instrument is calibrated when there is none of the target gas present.
Span: The point at which the instrument is calibrated when a known quantity of the target gas is
present.
Calibration Gases
User calibration of the instrument will improve the data accuracy in the range of the calibration gases
used. However, it may cause less accurate readings of concentrations outside this calibrated range.
Users should select the correct calibration gas for the expected gas levels on their particular
application. Only use gases with a known certified gas concentration.
Note: Certified calibration gases can be supplied by QED.
For each gas used the appropriate material safety data sheet must be read and understood
before proceeding. Calibration gases and the use of pressure regulators can be dangerous.
Calibration Set-up
The regulator supplied with the calibration kit has been configured to deliver a fixed flow. It only
requires a few turns to open and no adjustment is necessary.
Exhaust Port
When the instrument is being calibrated, there are two possible exits for the gas; via the
usual manner out of the exhaust port of the instrument or in cases of over-pressurisation
the 1/16” port on the pressure relief valve.
It is recommended that both ports have exhaust tubing attached. The exhaust tubing must
emerge in a well-vented area. Ensure there are no leaks in the tubing and connections.
The calibration should always be carried out in a safe area with all necessary precautions
taken as all pressurised gases are potentially dangerous.