Shielded, Fiber-Optic Transmission Probe for Demanding Near-IR Process Analysis Applications

Axiom Analytical, Inc. has announced the FPT-850RG “Rock Guard” Near-Infrared Transmission Probe. The new probe facilitates chemical composition monitoring of process streams containing large pieces of hard particulate matter – often called “Bricks” or “Rocks” in the chemical industry. It includes a robust shielding structure – fabricated from either stainless steel or Hastelloy – which effectively protects the probe optics while allowing unimpeded chemical analysis of the circulating liquid stream.

In common with the Company’s existing FPT-850N Near-IR and FPT-850V Visible Transmission Probes, the Rock Guard probe has been developed to provide maximum long term reliability under the extreme conditions of high temperature, thermal shock, and aggressive chemistries encountered in many on-line process applications. The probe design has two key elements. The first is a proprietary sealing technique involving a direct sapphire to metal welded pressure seal (U.S. Patent 6,587,195 B1). This approach provides significant advantages over other sealing techniques. A high degree of chemical resistance is assured by the fact that the only materials in contact with the process are sapphire, high nickel alloys, and a thin flash of either gold or PTFE (application dependant). The compliance required to withstand extreme temperature cycling is provided by the high nickel alloy seal which is compressed at high pressure prior to welding. This approach eliminates fatigue and stress failures common with brazed seals as well as the limited lifetime characteristic of elastomeric seals.

The second key element of the FPT-850 design is the elimination of optical fibers within the probe (U.S. Patent 5,418,615). This insures excellent optical stability and long term reliability. The elimination of both internal optical fibers and elastomeric seals provides for reliable long term operation at temperatures as high as to 400ºC. FPT-850N Near-infrared Transmission Probes are widely used for on-line process analysis in the chemical, petroleum, and pharmaceutical industries as well as in process development and related PAT (Process Analytical Technology) applications.