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D5305-23 – Standard Test Method Technical Guide
📋 Scope and Significance
ASTM D5305-23 provides a field method for measuring ethyl mercaptan in LP-gas vapor using length-of-stain tubes, with detection from 0.5 to 120 ppm by volume, specifically reliable at 5 ppm or more. This standard is important because LP-gas is colorless and odorless; ethyl mercaptan is added as an odorant to warn users of leaks. The test enables rapid on-site verification of odorant levels.
🔬 Test Method and Procedure
The test uses a manually-operated vacuum pump to draw vapor from an LP-gas cylinder or tank through a detector tube. The stain length indicates concentration, read from a manufacturer scale. The method is simple and does not require complex equipment. However, interferences such as methyl mercaptan can affect results, so tube selectivity should be verified.
| 🟦 Parameter | 📏 Specification |
|---|---|
| Detection Range | 0.5 – 120 ppm by volume |
| Reliable Range | ≥ 5 ppm by volume |
| Detection Technique | Length-of-stain tube |
| Sample Source | Vapor space of LP-gas containment |
Tip: Ensure the vacuum pump is properly calibrated per manufacturer instructions for accurate volume measurement. Store detector tubes in a cool, dark place and use before expiration.
Warning: Methyl mercaptan is a known interference that can produce false results. Always confirm the tube specificity for ethyl mercaptan.
❓ Frequently Asked Questions
🔍 What is the detection range of the test?
It can detect ethyl mercaptan from 0.5 to 120 ppm by volume, with reliable application for concentrations of 5 ppm or more.
💡 Why is this method used?
It allows quick field measurement of odorant levels in LP-gas without lab equipment, ensuring safety by confirming adequate odorization.
⚡ What equipment is needed?
A manually-operated vacuum pump and a detector tube designed for ethyl mercaptan are required. The pump draws a measured vapor sample through the tube.
📌 What substances interfere with the test?
Methyl mercaptan can interfere with detector tubes for ethyl mercaptan. Users should review manufacturer data on cross-sensitivity.