The article examines the development of technical and operational requirements for a sample preparation unit for a sorption-capacitive water dew point temperature transmitter in natural gas. The research shows that avoiding an additional methodological bias in water dew point temperature measurement requires preservation of the sample moisture content and single-phase state during sampling, throttling, transportation, and delivery to the measuring chamber. The paper analyses existing stationary and mobile systems for gas sampling, filtration and sample conditioning, as well as probe-type devices installed directly into pipelines. The authors demonstrate that known solutions primarily provide filtration, pressure and flow rate regulation, removal of interfering components or representative sampling from the stream, but only partially address the problem of thermal stabilization of the sample after throttling.

   A distinctive feature of the under consideration is the integration of functions within a single structural assembly: extracting the sample from a representative zone of the flow, throttling, protecting the throttling elements and performing intra-pipe thermal stabilization.

   The article outlines requirements for the mounting plate, heat exchange fin, impulse tubes with enhanced heat transfer, throttle valve, measuring chamber and construction materials. The authors show that the geometry of the immersion section, the surface area of heat exchangers, the length of the thermal stabilization tubes and the thermophysical properties of materials must be treated as interdependent parameters. These factors collectively determine the preservation of the sample's single-phase state and prevent any additional methodological bias in the water dew point temperature measurement results.