BS ISO 23978:2020 pdf download.Natural gas — Upstream area — Determination of composition by Laser Raman spectroscopy
1 Scope
This document describes a laser Raman spectroscopy method for the quantitative determination of chemical composition of natural gas in upstream area.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 6142-1, Gas analysis — Preparation of calibration gas mixtures — Part 1: Gravimetric method for Class I mixtures
ISO 6144, Gas analysis — Preparation of calibration gas mixtures — Static volumetric method
ISO 6145, Gas analysis — Preparation of calibration gas mixtures using dynamic methods
ISO 10715, Natural gas — Sampling guidelines
ISO 11095, Linear calibration using reference materials
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at http://www.electropedia.org/
3.1 Raman
effect process, in which photons from a light source are absorbed by the electrons surrounding polyatomic molecules and result in a new photons being emitted at wavelengths higher or lower than the source photon wavelength
Note 1 to entry: The resulting wavelength changes are called Raman shifts. The Raman shifts are determined by the vibrational and rotational frequencies of the atomic bonds within each molecule.
3.2 multichannel
photodetector photosensitive semiconductor device that transports electric charge from one capacitor to another, allowing serial output of parallel data, typically used for digital image capture
Gas concentrations are calculated for a specified period. Because each discrete detector collects photons at one wavelength, one detector position is typically needed to detect each natural gas species. NOTE Currently, only analysers with 8 APD detector positions per module are available. 8 is sufficient for some natural gas applications, however, if more than 8 gases need to be measured, two or more detectors can be operated in parallel.
5 Instruments
5.1 Laser Raman gas analyser
The type of Raman gas analyser is selected according to the types of gases and the natural gas concentration ranges of interest. The base analyser unit contains a laser, optical path control, gas detection chamber, photon detection and processing, signal processing, and human/machine interface. The analyser should have sensitivity sufficient to detect the components in the analytical range given in Table 1. It should keep a stable state after zero calibration.
BS ISO 23978:2020 pdf download
