AS 26142 pdf download

AS 26142 pdf download

AS 26142 pdf download.Hydrogen detection apparatus — Stationary applications (ISO 26142:2010 (ED 1.0) MOD)
1  Scope
This International Standard defines the performance requirements and test methods of hydrogen detection apparatus that is designed to measure and monitor hydrogen concentrations in stationary applications. The provisions in this International Standard cover the hydrogen detection apparatus used to achieve the single and/or multilevel safety operations, such as nitrogen purging or ventilation and/or system shut-off corresponding to the hydrogen concentration. The requirements applicable to the overall safety system, as well as the installation requirements of such apparatus, are excluded. This International Standard sets out only the requirements applicable to a product standard for hydrogen detection apparatus, such as precision, response time, stability, measuring range, selectivity and poisoning. This International Standard is intended to be used for certification purposes.
3  Terms and definitions
For the purposes of this document, the following terms and definitions apply. 3.1 alarm set point fixed or adjustable setting of the hydrogen detection apparatus that is intended to select the hydrogen volume fraction at which an indication, an alarm or another output function will automatically be activated 3.2 ambient air normal atmosphere surrounding the hydrogen detection apparatus 3.3 aspirated hydrogen detection apparatus hydrogen detection apparatus that samples the gas to be detected by introducing it to the hydrogen sensor(s) in a forced manner (e.g. use of a gas sampling pump or induction of a flow through a pressure differential) 3.4 clean air air that is free of flammable gases, interfering or contaminating substances, and dust 3.5 control unit part of hydrogen detection apparatus that is commonly referred to as the apparatus body and which excludes its remote sensor(s) and connections, if any 3.6 data collecting interval time interval between the time when an indication data is collected and the time when the next indication data is corrected 3.7 diffusion chamber chamber that can be sealed with controlled conditions of temperature, humidity and test-gas volume fraction, used for performing the test on the hydrogen detection apparatus 3.8 fault signal audible, visible or other type of signal different from the alarm signal, providing, directly or indirectly, a warning or an indication that the hydrogen detection apparatus is not working satisfactorily 3.9 final indication indication given by the hydrogen detection apparatus after stabilization 3.10 hydrogen detection apparatus assembly with an integrated or a remote hydrogen sensor that is intended to detect and measure the hydrogen volume fraction over a declared measuring range Note 1 to entry: The hydrogen detection apparatus may be provided with a single or multiple alarm set points. Note 2 to entry: The hydrogen detection apparatus may include one or more built-in alarm indications, output contacts for alarm and/or electrical signals for alarm. 3.11 hydrogen sensing element component that provides a measurable, continuously changing physical quantity in correlation to the surrounding hydrogen volume fraction 3.12 hydrogen sensor assembly, which contains one or more hydrogen sensing elements and may also contain circuit components associated with the hydrogen sensing elements, that provides a continuously changing physical quantity or signal in correlation to the physical quantity provided by the hydrogen sensing element(s) 3.13 hydrogen volume fraction hydrogen content expressed as the ratio of the volume of hydrogen to the total volume of all components in the gas mixture under standard conditions of temperature and pressure of 20 °C and 101,325 kPa 3.14 interferant any substance that affects the sensitivity of a hydrogen sensing element by contacting or adhering to it 3.15 latching alarm alarm that, once activated, requires deliberate manual action to be deactivated 3.16 measuring range range, defined by the lowest and highest hydrogen volume fractions, within which a hydrogen detection apparatus can measure hydrogen volume fractions within the specified accuracy 3.17 multi-level detection continuous detection and monitoring of hydrogen volume fraction with multiple alarm set points 3.18 nominal supply voltage voltage corresponding to the manufacturer-recommended operating voltage for the hydrogen detection apparatus 3.19 poisoning phenomenon caused by any interferant that permanently affects the sensitivity of a hydrogen sensing element

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