Staff responsible for health, safety and environmental monitoring often find that high value monitoring equipment is necessary for specific applications. However, if that equipment is only needed infrequently, the cost of the equipment can be preclusive so instrument hire is the obvious solution.
In applications where it is only necessary to monitor a single gas such as carbon monoxide or a specific solvent such as toluene, a relatively low cost analyser would suffice. However, many of Quantitech’s customers require the capability and flexibility of Gasmet FTIR (Fourier Transform InfraRed) gas analysis, but this comes with a heavier price tag, so the company has invested in small rental fleet of Gasmet FTIR analysers for both hot and ambient gas monitoring applications.
What’s so special about FTIR?
As a multigas monitoring technology, FTIR is generally preferable when two or more gases need to be monitored simultaneously. An FTIR spectrometer obtains infrared spectra by first collecting an ‘interferogram’ of a sample signal with an interferometer, which measures all infrared frequencies simultaneously to produce a spectrum.
Over a number of years, Gasmet has established a library of FTIR reference spectra that now extends to a collection of 5000+ gases and vapours. The instrument’s PC based software (Calcmet) provides the capability to simultaneously quantify up to 50 gases, re-analyse archived spectra and identify unknown gases (a major advantage of FTIR).
The development of portable FTIR has radically improved the ability to both identify unknown gases and easily add new components to the analytical model, which is a major advantage because of the inherent risks involved with only looking for known contaminants. In addition, by providing real-time data for multiple compounds simultaneously users are able to survey sites much more effectively, identifying hot spots and monitoring trends.
Gasmet FTIR analysis systems are able to monitor multiple gases simultaneously even in emissions that are hot, corrosive and high in moisture, so these analysers are ideal for a wide variety of process control and emissions monitoring applications. The Gasmet DX4000 is popular for renting because of its portability and flexibility; it has the same capability as a rack mounted CEMS, but provides users with the ability to measure almost any gas at multiple sites, so it can be used to verify fixed CEMS, and for research and investigative work.
The DX4000 is typically set up to measure H2O, CO2, CO, NO, NO2, N2O, SO2, NH3, CH4, HCl, HF and a variety of different VOC´s, but additional gases can be added without any hardware changes. Easy-to-use Calcmet™ software is supplied with the analyser and results can be displayed in ppm, mg/Nm3 or Vol-%. All measurement data and spectra can be stored for later analysis.
The Gasmet FTIR analyser is MCERTS approved for nine of the most important parameters. However, with such a vast array of measurable parameters possible, existing users are also able to take measurements that help improve process control.
In the hot applications outlined above, sample gas has to be maintained at a high temperature to prevent condensation, which may affect the readings and damage analyser components. However, this is not an issue in ambient applications such as occupational safety, leak detection, emergency response and odour investigation.
Traditionally, ambient assessments would be undertaken by gas sampling and laboratory analysis or by leaving sorbent tubes at strategic locations for a period of time and then later removing these for laboratory analysis, but both of these methods are flawed in a number of ways. Gas sampling merely provides a ‘snapshot’ of air quality at a single location at a single moment in time and is therefore unlikely to be truly representative, and sorbent tubes simply provide an average measurement over a period of time, often for a single location. Both of these methods are unlikley to identify potentially dangerous peaks, and both of them incur a significant delay before results are available.
Portable instruments that are able to provide real-time readings are therefore preferable. However, most portable instruments either only measure a single gas, or are unable to speciate different gases, which often causes false positive readings when the air sample contains more than one volatile organic compound for example.
The new Gasmet DX4040 portable FTIR multi-gas analyser is available for hire from Quantitech. This unit contains exactly the same analyser components as other Gasmet FTIR instruments, but is housed in a backpack and communicates wirelessly with a PDA.
The PDA enables users to measure up to 25 (user defined) gases simultaneously, but the DX4040 can also operate with a laptop or PC to analyse spectra for thousands of gases. This means that the technology can be employed for the investigation of unknown gases.
Once an FTIR instrument has been configured, monitoring can be extremely simple. However, Quantitech’s in-house experts are available to guide users through the process.
FTIR provides enormous capability in both ambient and hot gas applications, and with the development of portable instruments, this technology has become the mainstay of Quantitech’s rental activities; either as a ‘try before you buy’ option, or in short-term rental applications in which multiple gases are monitored simultaneously.
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