How Closed Loop Sampling Systems Work

A closed loop sampling system creates a sealed circuit between your process line and the sample container, ensuring that the process fluid never contacts ambient air during extraction. The system typically consists of a sampling panel with isolation valves, a purge/vent circuit, and a sample cylinder connection point.

The operational sequence follows four steps: (1) Connection — the sampling assembly connects to a process tap via flange or threaded fitting; (2) Purging — process fluid flushes through the entire circuit to displace residual material; (3) Filling — the sample flows into the cylinder under controlled pressure; (4) Isolation — all valves close and the sealed cylinder is disconnected for lab analysis. The entire cycle takes 3-8 minutes depending on fluid properties and purge volume requirements.

For volatile streams (LPG, naphtha, gasoline), constant-pressure piston cylinders maintain the sample at process pressure, preventing light-end flash vaporization that would corrupt RVP and distillation analysis. For stable liquids (diesel, lubricants), standard stainless steel cylinders provide reliable service at lower cost.

Key Technical Specifications

Common Applications

• Oil Refineries: Crude feed sampling, gasoline blend stock, diesel, jet fuel, LPG, naphtha
• Petrochemical Plants: Ethylene/propylene feedstocks, aromatics (BTX), polymer intermediates
• Natural Gas Processing: NGL, condensate, rich/lean glycol, amine solutions
• Pharmaceutical: Solvents, reaction intermediates, API precursors (GMP compliant)

Certifications & Standards Compliance

All Wanan sampling systems are manufactured under ASME U-Stamp certification at our Honghu, Hubei facility. Material traceability per EN 10204 3.1 is maintained throughout. For European installations, PED 2014/68/EU compliance is available. For explosive atmosphere installations, ATEX/IECEx certification is provided. Sour service (H2S) applications use NACE MR0175/ISO 15156 compliant materials.