Laboratory Analyst Training Curriculum
Mod 1 - Sampling
Module from the Laboratory Analyst Training Curriculum curriculum.
Module 1 — Sampling Procedures · Learning Objectives · 1. Identify appropriate sampling methods for liquid, gas, and solid refinery streams. · 2. Execute grab, composite, and online analyzer sampling per ASTM D4057 and D4177. · 3. Apply correct container selection, labeling, and chain-of-custody for routine and dispute samples. · 4. Correlate online analyzer readings with periodic grab-sample lab results. · 5. Recognize and control common sampling errors (flashing, stratification, contamination). · Sampling Methods — ASTM Reference
| Method | Title | Typical Use |
|---|---|---|
| ASTM D4057 | Manual Sampling of Petroleum Products | General liquid grab and composite sampling |
| ASTM D4177 | Automatic Sampling of Petroleum Products | Pipeline composite sampling, custody transfer |
| ASTM D5842 | Sampling for Vapor Pressure Determination | Gasoline RVP per D323/D5191 |
| ASTM D5854 | Mixing and Handling of Liquid Samples | Container handling, subsample homogenization |
| ASTM D1265 | Sampling LPG (Manual Method) | Propane, butane, LPG cylinders |
| ASTM D1145 | Sampling Natural Gas | Flare gas, fuel gas, vent streams |
| ASTM D4840 | Sampling Chain of Custody | Dispute / environmental / regulatory samples |
| Sample Container Selection | ||
| Stream | Container | Cap / Seal |
| Gasoline / MoGas | 1-qt epoxy-lined metal or amber glass | Foil-lined, tight-seal |
| Jet Fuel / Kerosene | 1-L amber glass, clean and dry | PTFE-lined cap |
| Diesel / ULSD | 1-L amber glass or epoxy-lined metal | PTFE-lined |
| Crude Oil | 1-L wide-mouth amber glass | PTFE-lined |
| LPG / Light Ends | Stainless floating-piston cylinder | DOT-approved valve |
| H2S-bearing Gas | Tedlar bag or stainless cylinder | Septum or stainless valve |
| Lube Oil | Clear glass, low-metals rinsed | PTFE-lined |
| Naphtha / NGL | Stainless cylinder, chilled receiver | DOT cylinder valve |
| Sampling Point Types & Best Practice | ||
| Point Type | Guidance | Common Issues |
| Tap sample (cooler) | Purge 5× line volume; chill to <100 °F | Flashing if stream >200 °F at sample tap |
| Line-mounted probe | Use mid-stream probe; avoid dead leg | Stratified sample, wall deposits |
| Tank bottom/middle/top | Composite at 1/6, 1/2, 5/6 tank level | Water/sediment phase at bottom |
| Autosampler composite | Flow-proportional per D4177 | Pacing failure during rate swings |
| Online analyzer | Filter; maintain fast loop <60 s response | Drift vs. lab grab correlation |
| Drum / tote | Top, middle, bottom grab via thief | Stratification, water bottoms |
| Online Analyzer Correlation | ||
| Analyzer | Property | Grab Correlation Frequency |
| NIR / FTIR | RON, MON, RVP, distillation | 1× per shift vs. D2699/D2700/D86 |
| Process GC | C1–C10 composition | Daily vs. D2163 / D5134 |
| Sulfur analyzer (UV fl.) | Total S on diesel/gasoline | 2× daily vs. D5453 |
| Density meter | API gravity | Each batch vs. D1298 / D4052 |
| Cloud / pour analyzer | Cloud, CFPP | Daily vs. D2500 / D6371 |
| Common Sampling Errors | ||
| Error | Cause | Prevention |
| Light-ends flash loss | Sample >100 °F; loose cap | Chill sampler; tight PTFE seal |
| Water entrainment | Sample drawn from line bottom | Probe at pipe centerline |
| Contamination | Reused uncleaned container | Dedicated, labeled containers |
| Cross-contamination | Insufficient line purge | Purge 3–5× line volume |
| Composite imbalance | Flow-rate pacing loss | Verify pacing each shift |
| ◄ Return to Instructions |
Source: Laboratory_Analyst_Training_Curriculum_v1.xlsx · Sheet: Mod 1 - Sampling
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