AS2290.3 has been revised for 2018.
The following provides a guide to help those using gases for testing and calibration in Australian coal mines. This is a guide and you should purchase the standard to be fully knowledgeable in all aspects of the requirements.
Calibration – Key sections and definitions:
Section: 1.3.4 and 1.3.4 reference calibration – ISO 17025
Section: 1.3.6 defines certified test gas
“Certified test gas” for calibration:
One of the main differences between the two standards is in the definitions of terms. The most important change is the definition of “Certified test gas:”
|Mixture of a test gas and diluent in which the true content of the test gas, with a confidence level, is accepted by the relevant Regulatory Authority.||Mixture of a test gas and diluents, in which the true content of the test gas is known, with a
confidence level and with a certificate from a laboratory or reference material producer that
meets the requirements of AS ISO/IEC 17025 or AS ISO 17034 respectively.
The term ‘test gas’ must be taken as an industry term, interchangeable with ‘calibration gas.’ Both versions allow the use of diluents, so long as the content of the ‘test gas’ is known. Diluents could be used to dilute a single gas mixture into multiple mixtures for use in multi-point calibrations.
In the previous standard, any ‘test gas’ was acceptable so long as the Regulatory Authority approves it for use. The Regulatory Authority in this case is NATA. It is generally understood that most gases were acceptable so long as they were manufactured in such as a way as to be traceable to a recognised national metrological authority, such as N.I.S.T. (USA) or NPL (UK).
In the new standard, the new wording means that gases require a certificate related to the accreditation on the gas mixture. These certificates can be produced by facilities accredited to ISO17205 Testing, ISO17025 Gas Calibration, or ISO17034 Reference Material Producer, where the scope of accreditation covers the required compounds and amounts (mixture composition). The facility must also be accredited by a signatory to the ILAC MRA, which are regulatory authorities (like NATA) from other countries.
Certified test gas (ISO 17025) for calibration would be used for the six monthly calibrations under Section 4.7. This would include hand held instruments, machine mounted and fixed & transportable. Section 5.7 references Tube Bundle Systems.
“Span Gas”- Key Sections and definitions
1.3.36 Span Gas
1.3.17 Span Test
4.4 Span Test
4.5 Response Time Test
A new definition, “Span gas,” has been added. Span Gas is defined as a:
“test gas that enables a gas detector to be exercised at a concentration exceeding the uppermost alarm setpoint of the gas detection system.
1 A test gas can be a certified gas mix, or a dilution of pure gases made using suitable mixing equipment. It is not mandatory that span gas is a certified gas.
It would be up to the end user to prove that reasonable steps were taken to ensure accuracy in test gas. CAC Gas recommends that only gravimetrically produced traceable gas mixtures are used for any test or calibration.
Span test (4.4)
Application of a span gas to the detector without adjustments to zero, sensitivity, or alarm level to verify the correct operation of the detector.
Response time test (4.5)
A span gas shall be presented to the detector using the manufacturers supplied or recommended fitting to the sensor or sensor head
Span gas is used for testing instruments prior to use, daily, weekly and monthly.
For complete details outlining the requirements for testing or calibrating gas measurement equipment before use, daily, weekly, monthly and six monthly, purchase the standard AS/NZS 2290.3:2018 from SIA Global.
CAC GAS can provide all gas mixtures for all coal mining applications.