What is the difference between closed loop and open loop sampling?

Closed loop sampling keeps the process fluid in a sealed system from the process line to the sample cylinder, with zero atmospheric exposure. Open loop (grab) sampling involves opening a valve and collecting fluid in an open container, exposing both the operator and the sample to ambient air. Closed loop is required for hazardous, volatile, or moisture-sensitive fluids.

How often do sampling cylinder seals need replacement?

Under normal service, PTFE-based seals in 316L stainless steel sampling cylinders should be replaced every 2-3 years. In aggressive service (sour/H2S, high-temperature cyclic, or corrosive chemicals), annual seal replacement is recommended. Visual inspection of seals should be conducted monthly, with immediate replacement if any deformation, cracking, or chemical attack is observed.

Can closed loop samplers handle two-phase or slurry streams?

Yes, with proper engineering. Two-phase streams require modified panel designs with larger bore tubing (minimum 3/8 inch), specialized valve configurations, and potentially heated panels for high-viscosity service. Slurry applications may need purge protocols with flush solvent between samples to prevent cross-contamination and plugging.

What pressure ratings are available for sampling panels?

Standard Wanan sampling panels are available in Class 150 (2.0 MPa), Class 300 (5.0 MPa), and Class 400 (6.4 MPa) ratings. Custom designs for higher pressures (up to Class 600 / 10.0 MPa) are available for high-pressure process applications. All pressure-bearing components are hydrostatically tested at 1.5x design pressure before shipment.

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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.

主要技術規格

參數	Typical Range
Design Pressure	2.0 - 6.4 MPa (Class 150 - 400)
Design Temperature	-40 to +350 C
Wetted Material	316L Stainless Steel (standard); Hastelloy C-276 (corrosive service)
Cylinder Volume	150 mL - 4 L (standard: 500 mL, 1 L)
Connection Standard	ANSI B16.5 flange / NPT threaded / DIN
認證	ASME U-Stamp, PED 2014/68/EU, ATEX, GB/T 150

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.