Optimizing Performance of Model 42i Gas Analyzers
Volume II, Edition 5
Consider these 5 tips and tricks when measuring NO, NO2, and NOx:
Say goodbye to desiccante
Avoid maintenance chores associated with an external desiccant column such as refilling the desiccant column and proper disposal of the desiccant. A low-maintenance, high-performance alternative is the permeation dryer method. The permeation dryer uses a membrane dryer to remove water from the air for the generation process of ozone. This method offers better linearity, variability in moisture removal, very low maintenance requirements, and consistent performance. To upgrade your existing instrument, contact Technical Support by email or by calling (866) 282-0430, option 2.
Ensure you have the latest perm dryer design
Design enhancements have been made to the perm dryer assembly, allowing for a smaller, more compact design. The new design is optimized to eliminate friction so tubing is less susceptible to tears, holes and other damage. To order the new design, contact Customer Service by email or by calling (866) 282-0430, option 1. If the analyzer doesn't have a perm dryer installed already, you need to purchase the perm dryer, part number 113982-00 plus additional parts. If the analyzer already has a perm dryer and you want to replace the perm dryer you can just order the perm dryer, part number 113982-00.
Take care of the ozone cleanser
The ozone cleanser has 4 purposes:
- The cleanser acts as a particulate barrier to protect the ozone capillary from becoming clogged, especially in units with an external desiccant column.
- The internal media removes trace amounts of acids generated in the process of creating ozone by the internal ozonator. The removal of the acids protects the surface area of the gold coated reaction chamber where the chemiluminescence reaction takes place to measure Nitric Oxide (NO).
- In the event the desiccant column becomes “Spent” and the desiccant turns pink, the ozone cleanser acts to dry the air and prevent additional moist air from entering the reaction chamber.
- US EPA reference method designation status is achieved with the ozone cleanser installed on the 42C series and Thermo Scientific™ Model 42i series of gas analyzers
Replacing the ozone cleanser should be part of annual maintenance. To replace the ozone cleanser, disconnect the tubing from the top and bottom of the cleanser. Remove the cleanser from the mounting clips and then install the replacement cleanser on the mounting clips. Reattach the tubing to the top and bottom of the ozone cleanser and your instrument is up and running! To order an ozone cleanser, email or call customer service at (866) 282-0430 option 1 and request part number 101016-00.
Optimize performance with the proper converter
When choosing between a stainless steel converter and a molybdenum converter, consider application, process environment, and accuracy demands. As a rule of thumb, coal-fired, ambient, and dilution applications should run molybdenum (also known as moly) converters, and gas turbines should use a stainless steel converter.
Determining the appropriate converter also depends on specific factors in the process. To achieve best results for low level concise accuracy, opt for a moly converter. When high levels of NO2 are present, a stainless steel converter is longer lasting and a more economical alternative. If ammonia slip is suspected and you’re using stainless steel converter, add an ammonia scrubber since ammonia might be present in the sample. Contact Tech Support for additional recommendations.
Additional resources for converter efficiency
A procedure for performing converter efficiency tests may be regulated in order to document the analyzer is collecting data of known quality. If this is the case for your process, an approved method for conducting a converter efficiency test is required. For ambient applications, refer to National Primary and Secondary Ambient Air Quality Standards, 40 CFR Part 50, Appendix F or refer to the instruction manual for your instrument. For the measurement of nitrogen oxides (NOX) operators of stationary sources, refer to METHOD 7E—Determination of Nitrogen Oxides Emissions from stationary sources (Instrumental Analyzer Procedure).