Have you ever sipped into your Romex Coveralls and walked the plant floor to locate an analyzer that needs servicing, only to open the access panel on the analyzer, and find a mess of wires and fiber optic cables?

Fiber Optic Cables Part of Total NIR or UV-VIS Analytical System

A complete Guided Wave system has three main components: 1) the analyzer, 2) the fiber optic cables, and 3) the sample interface. Optical grade fiber cables are used to carry the light from the analyzer to the sample and back. Using high performance fiber cables permits the sample interface to be located 100 meters, or more in some cases, from the analyzer for safety or convenience.

Additional Meter of Fiber Cable Allows for Easier Service and Repair

Guided Wave recommends an additional meter of fiber cable to allow for service and repair. Repairing a broken fiber termination is much preferred to replacing the entire cable. The Fiber Junction Box provides safe storage for this fiber cable. Consider installing a fiber junction box next to your NIRO analyzer.

• Provides a safe and clean storage solution for fiber service loops
• Improved Cable Management – Reduces cable clutter inside of the analyzer box
• Meets safety and care requirements per OEM instructions.

To learn more about how the Fiber Junction Box can help save you time and money during routine service, contact Guided Wave

Diisocyanates are a family of chemicals used to make a wide range of polyurethane products. The most widely used aromatic diisocyanates are toluene diisocyanate (TDI) and methylene diphenyl diisocyanate (MDI). Less widely used, but still important, are the aliphatic diisocyanates, including hexamethylene diisocyanate (HDI), hydrogenated MDI (H12MDI), and isophorone diisocyanate (IPDI).

• TDI is mainly used to make flexible polyurethane foam that can be found in a wide range of everyday products, including furniture, bedding, carpet underlay, and packaging.
• MDI is used primarily to make rigid polyurethane foams such as insulation boards.

Multiple process points during diisocyanate production can benefit from real-time monitoring with NIR analyzers. For example, the yield of TDI and MDI can be determined. Additionally, the concentration of water which can cause off-spec products to form in the reaction vessel can also be monitored. Once the reaction is complete, the acid number (polyol value) of the prepolymer can be monitored to ensure the product is on-spec. Determining the urethane yield can also be achieved by NIR.

During polyurethane synthesis, isocyanate is reacted with an alcohol to form a urethane. This reaction process creates the carbamate functional group which forms the links in polyurethane. Along with acid number (polyol value), NIR analyzers such as the ClearView db photometer can be used to monitor the conversion efficiency of isocyanate to urethane. By monitoring these properties with an NIR analyzer, problems can be quickly detected and corrected, and as a result reaction yields will improve.

Styrene acrylonitrile resin, known as SAN, is a copolymer plastic consisting of styrene and acrylonitrile. Due to its superior thermal resistance, it is widely used in place of polystyrene. By weight the relative composition is usually 70-80% styrene and 20-30% acrylonitrile. Mechanical properties and chemical resistance of SAN can be improved with a larger acrylonitrile content, but the compromise is a yellow tint to the normally transparent plastic. Product from this plastics family includes food containers, water bottles, kitchenware, computer products, packaging material, battery cases and plastic optical fibers. Styrene gives the plastic a nice glossy finish. Styrene revenue is projected to increase at a compound annual growth rate (CAGR) of over 9% from 2019 to 2025, according to the Global Newswire network. They report an increased demand in the manufacture of various products, using acrylonitrile butadiene styrene (ABS), expanded polystyrene, and polystyrene as the contributing factors.

Getting the correct blend of copolymers to achieve the desired physical properties can be a challenging task for process engineers in the polymer industry. Near-infrared (NIR) spectroscopy is a convenient and cost-effective tool for monitoring reaction processes in situ to ensure that the correct chemical ratios, average molecular weight, and physical properties are within specifications.

When transparency is a concern, the process engineer has several options. If polystyrene’s mechanical properties are insufficient, the process engineer can tailor a specific formulation of styrene-acrylonitrile copolymers or SANs (Figures 1 and 2). These copolymers typically contain between 20–30% acrylonitrile. Due to the polar structure of acrylonitrile, SANs copolymers have better resistance to breakdown in hydrocarbon streams than polystyrene. SAN copolymers also have a higher softening point, rigidity, and impact strength, yet maintain their transparency.

By incorporating a near-infrared (NIR) spectrometer and in situ process probe, a process engineer can quickly identify when the mixture of component concentrations are out of specification. The NIR region of the electromagnetic spectrum measures the overtone and combination bands of the C-H, O-H, and N-H fundamentals absorption bands. These spectra are unique to the molecule thus permitting the process engineer to make real-time corrections and ensure that product quality is maintained. In the case of SANs, NIR spectroscopy can be used to monitor the concentration of Styrene, Acrylonitrile, and MEK molecules

Today the use of DG-NIR analyzers continues to improve the accuracy and speed of measurements for polymer feed concentrations that can be achieved with both Guided Wave analyzers; the NIR-O full spectrum NIR analyzer or the ClearView db photometer. By collecting these data, process engineers in the polymer plant can make informed decisions on process optimization to ensure product quality.  

The proof of concept study presented in this application note illustrates that Guided Wave process analyzers can detect changes in concentration as little as 0.1 %wt.

The most important variable affecting the glycol production is properly managing the water-to-oxide ratio. In commercial plants, improvement in yields can occur with a large excess of water under controlled pH levels in the solution. Tim Felder, President of Felder Analytics, a thirty-five-year veteran in applied process analytical technologies (PAT) states, “The trick is to measure and control the level of water to prevent any uncontrolled exothermic reaction. When this is done, both safety and yields are improved in the process.” He continues, “Guide Wave’s technology was selected by a leading worldwide EG producer as the most achievable control technology for measuring this process.”

Many EG manufacturers prefer using Guided Wave’s NIR instruments, due to the state-of-the-art design, repeatability, stability and elimination of drift. Both analyzers, the full spectrum NIR-O spectrometer or the ClearView db photometer make managing this measurement efficient. Either analyzer can be used successfully, the choice depends on the complexity of the application (i.e., number of measurements, varying chemistries, number of sample points and measurements). View the Feasibility Study