This test method is for the online determination of vapor phase moisture concentration in natural gas using a tunable diode laser absorption spectroscopy (TDLAS) analyzer also known as TDL analyzer. TDL absorption spectroscopy provides readings as a concentration of the moisture such as percent, part per million by volume (ppm) or milligrams per cubic meter. The concentration values are not dependant on pressure assuming the sample is always in gas phase. The moisture dew point is dependant on pressure; if dew point values are required, they are calculated according to ASTM D1142 or ISO 18453. Dew point conversions are not covered in this document.
Moisture content in pipeline gas is a concern of distributers and suppliers of natural gas and other gaseous fuels. Accurate moisture measurement is a critical parameter is assessing a fuels heating value and quality and is important in custody transfer transactions. TDL spectroscopy provides a method for rapid continous on-line measurement of moisture in natural gas and other gaseous fuels. This standard will provide a valuable tool to stakeholders such as gas companies, Public Utility Commissions, and users of pipeline gaseous fuels.
KeywordsPipeline, process pipe, NGL, LNG
The title and scope are in draft form and are under development within this ASTM Committee.Back to Top
Ballot Item Approved as D7904-2015 and Pending Publication