When measuring gases online by spectroscopy, a longer pathlength is usually required due to the low density of gaseous streams. Longer path length transmission probes for gas measurements are extremely effective, but more difficult to design due to several factors. These probes must be aligned over a greater distance and must permit easy servicing without upsetting the optical focus of the cell. Since many gas streams are considered hazardous, both a reliable and durable sealing mechanism is also critical.
Gas Probe
To ensure successful gas phase process stream measurements with the minimum amount of risk and downtime select the gas probe. Available in a variety of alloys and matched with several elastomeric o-ring types, it meets or beats most standards for use found in chemical plants, refineries, food, and food supplement processing facilities, semiconductor or electrical component fabrication shops, and pharmaceutical manufacturing plants.
Wide Operating Range
Because of its versatility and ruggedness, the Gas Probe is the leading option for online spectral analysis in phosgene, HCl, and hydrocarbon gas service. The sturdy design guarantees years of continuous use at high temperatures and pressures. An option to include 6mm thickness windows increases the maximum operating pressure to 1000 psig. Standard 316L stainless steel construction inhibits corrosion due to the elements. However, if harsh chemicals are a concern, a material upgrade to Hastalloy C-276 offers superior resistance to erosion.
Sealed Optics for Safety
Perhaps the most crucial aspect of any online probe design is the sealing approach. Since most gas streams will be under pressure and the composition is often hazardous, leaks are most undesirable. Additionally, moisture infiltration from the external environment adversely affects performance. The Gas Probe implements a multiple o-ring seal that effectively addresses both issues. See illustration below.
Gas Probe Design Features
- Clean out ports at each window
- Reproducible optical path length permits servicing in the field
- Rugged design translates to longer service life
- 25mm diameter optics minimize divergence losses and vignetting
- High optical throughput for low noise spectroscopy
- Compatible with most fiber optic based analyzers, according to fiber diameter and spectral range
Gas Probe Pathlengths and Operating Ranges
- Standard pathlengths: 25, 50, 75,100 cm (other lengths available)
- Temperature Ranges: -20 to 170 °C (o-ring dependent)
- Pressure Ranges:
0-500 psi (2mm Sapphire windows)
0-1000 psi (6mm Sapphire windows)
0-500 psi (6 mm Fused Silica (Deep UV))