As the vapor passes through the tube, the chemical reagent inside changes color (typically from white/light blue to dark brown or black). The length of the color stain corresponds directly to a scale printed on the tube, providing the H2Scap H sub 2 cap S concentration in ppm v/v. ASTM D5705 vs. Alternative Methods
The core of the test method can be summarized in a few steps: astm d5705 pdf
ASTM D5705 is a critical standard used in the natural gas industry for the rapid, on-site measurement of hydrogen sulfide (H₂S) content. This method employs a color indicator tube (often referred to as a “length-of-stain” tube) to determine H₂S concentrations ranging from approximately 0.5 to 100 ppm by volume. It is widely adopted for field quality control, pipeline integrity monitoring, and regulatory compliance because it requires no laboratory equipment or complex sample conditioning. As the vapor passes through the tube, the
The document is protected by copyright, and downloading it from unauthorized file-sharing websites may expose you to incomplete, outdated, or incorrect versions that do not carry the full legal weight of the official ASTM standard. Alternative Methods The core of the test method
[Sample Collection] ➔ [Heating & Agitation] ➔ [Vapor Extraction] ➔ [Colorimetric Analysis] 1. Apparatus and Material Preparation
Read the detector tube immediately after drawing the sample. The color boundary can fade or bleed if left sitting, leading to inaccurate readings. Conclusion
The standard is detailed and specific. For a test to be considered compliant, the following technical parameters must be met: