Koehler FK39990 LPG Copper Strip Corrosion Tester (ASTM D1838 Compliant)

Overview

The Koehler FK39990 LPG Copper Strip Corrosion Tester is a precision-engineered laboratory instrument designed to evaluate the corrosivity of liquefied petroleum gas (LPG) toward copper, in strict accordance with ASTM D1838, GPA 2140, and ISO 6251. This test method relies on the qualitative assessment of surface discoloration and tarnish formation on standardized copper strips after controlled exposure to vapor-phase LPG under defined thermal and pressure conditions. The apparatus implements a closed-system, vapor-phase immersion protocol where conditioned LPG samples are introduced into sealed stainless-steel test tubes containing polished copper strips; these tubes are then immersed in a thermally stabilized water bath maintained at 37.8 ± 0.5°C for a specified duration (typically 1 hour). Post-exposure, strips are cleaned and compared visually against the official ASTM D1838 color chart to assign a corrosion rating from 1a (bright, uncorroded) to 4c (heavily tarnished or blackened). The FK39990 delivers reproducible, auditable results essential for refinery quality control, pipeline specification compliance, and regulatory submission workflows.

Key Features

• Four-position parallel testing configuration enables simultaneous evaluation of multiple LPG batches or formulation variants—enhancing throughput without compromising inter-test consistency.
• Stainless-steel LPG test tubes rated to 1000 psi (6895 kPa) static pressure, each fitted with a precision 1/4″ needle valve for safe, metered sample introduction and venting.
• Microprocessor-controlled water bath with PID temperature regulation ensures sustained stability of ±0.5°C at the critical test setpoint of 37.8°C—meeting the tight thermal tolerance mandated by ASTM D1838.
• Dual-wall stainless-steel bath construction with optimized insulation minimizes ambient heat loss and improves energy efficiency during extended operation.
• Integrated Soxhlet-style reflux condenser and constant-level water reservoir maintain uniform thermal distribution across all four tube positions and prevent evaporation-induced drift.
• Compact footprint (30 × 25 × 61 cm) and lightweight design (8.6 kg) facilitate placement in fume hoods or dedicated QC laboratories without requiring structural reinforcement.

Sample Compatibility & Compliance

The FK39990 is validated for use with commercial-grade propane, butane, and propane/butane blends meeting ASTM D1835 or GPA 2140 specifications. It accommodates both field-collected cylinder samples and laboratory-prepared synthetic mixtures. All components—including copper strip dimensions (75 mm × 12.5 mm × 1.5 mm), polishing protocol, cleaning solvents (e.g., ASTM D129-compliant carbon tetrachloride or approved alternatives), and visual assessment methodology—are fully aligned with the procedural requirements of ASTM D1838. The system supports GLP-compliant documentation practices through traceable calibration records, operator logs, and environmental monitoring. Its design inherently satisfies mechanical and safety provisions referenced in OSHA 1910.106 and NFPA 58 for handling pressurized hydrocarbon vapors in analytical settings.

Software & Data Management

While the FK39990 operates as a benchtop analog instrument without embedded firmware or digital interface, it is fully compatible with external laboratory information management systems (LIMS) via manual data entry or barcode-assisted logging. Temperature setpoints, dwell times, and operator IDs can be recorded in structured electronic lab notebooks (ELN) compliant with 21 CFR Part 11 when paired with audit-trail-enabled software platforms. Calibration certificates for the integrated platinum resistance thermometer (PRT) and pressure-rated tubing assemblies are supplied with each unit, supporting IQ/OQ documentation for GMP-regulated environments. Routine verification per ASTM E74 or ISO/IEC 17025 is recommended every six months or after 100 test cycles.

Applications

• Refinery final product release testing for LPG shipments destined for domestic and export markets.
• Monitoring sulfur compound carryover (e.g., mercaptans, sulfides) in amine-treated streams prior to LPG fractionation.
• Validation of desulfurization catalyst performance across operating cycles.
• Investigation of storage tank corrosion mechanisms linked to trace contaminants such as hydrogen sulfide or elemental sulfur.
• Supporting technical service responses to customer-reported discoloration complaints in LPG-fueled appliances.
• Method transfer and interlaboratory comparison studies within API RP 4210-certified testing networks.

FAQ

What is the required copper strip preparation procedure before testing?
Copper strips must be polished sequentially with 120-grit, then 240-grit silicon carbide paper under running water, followed by thorough rinsing in acetone and drying with lint-free tissue—per Section 6.2 of ASTM D1838.
Can the FK39990 be used for testing gasoline or diesel fuels?
No—this instrument is specifically configured for vapor-phase LPG corrosion assessment. Liquid-phase fuels require distinct apparatus per ASTM D130 or D2670 and are not compatible with the FK39990’s pressure-rated tube geometry or thermal profile.
Is the water bath equipped with a drain valve for maintenance?
Yes—a bottom-mounted brass drain valve allows complete fluid evacuation without disassembly, facilitating periodic replacement of deionized water to prevent mineral buildup.
How often should the needle valves be serviced?
Valves should be inspected for leakage and smooth actuation prior to each test series; fluoropolymer-sealed units are rated for ≥5,000 cycles under typical laboratory usage.
Does Koehler provide certified reference copper strips?
Yes—Koehler supplies NIST-traceable, ASTM D1838-certified copper strips (Lot-coded, individually packaged) with full CoA, available under separate catalog number K-STRIP-LPG.