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Future-proofing with multigas monitors

28 January 2014

The popularity of multiparameter gas monitors that employ fourier transform infra-red technology has grown in recent years. Antti Heikkilä, from Gasmet, explains more about the technology and its increasing popularity.

As the quality of ambient air, engine and industrial emissions has improved, the monitoring instrumentation has needed to become more sensitive and to operate with lower detection limits. At the same time, the requirement to monitor has grown significantly, driven by regulations designed to protect both the environment and health, and to mitigate the effects of climate change. 

Gas monitoring instruments are, therefore, being continually being updated and improved to incorporate new technological developments and in response to new requirements. 

The general trend is towards smaller instruments which are lighter, easier to operate and require less power. However, the main improvements have been higher measurement precision, reduced drift and reduced cross-sensitivity from the gas matrix. At the same time there has been a move away from single gas instruments to multiparameter instruments, either employing a range of technologies or a multiparameter technology such as fourier transform infra-red (FTIR) FTIR.

As instrument reliability has improved, maintenance and calibration requirements have been reduced and service intervals have been extended. The tools of a service engineer have also changed; electronic circuit boards are no longer populated with potentiometers that require regular adjustment and software now adjusts the circuits digitally and reports any malfunction automatically.

Chemical test tubes and single gas monitors have lost market share because they risk failing to detect a dangerous leak. In contrast, multiparameter analysers enable operators to test for a wide range of gases simultaneously in the workplace, in stack emissions and in the ambient environment. 

Although these multi-parameter analysers are generally more expensive than single parameter analysers the cost comparison moves in favour of multi-parameter as more gases are measured, because the purchase cost of several individual analysers is likely to exceed the cost of a single multiparameter FTIR. In addition, the cost of ownership for FTIR is much lower because it does not need expensive re-calibration and the requirement for consumables is minimal.

Future-proofing monitoring capability
Many process operators have chosen multi-parameter FTIR because it offers the flexibility to add further gases at a later stage, helping to future-proof monitoring capability. This is one of the major reasons for the widespread adoption of FTIR technology. 

The flexibility of FTIR to analyse new gases without the need for additional hardware is particularly advantageous for manufactured products and processes which often change and necessitate an adjustment to the monitoring strategy. A further benefit of continuous process monitoring is that it provides an opportunity for feedback control of the process and/or the creation of alarms.

A variety of factors will affect the choice of analyser, but regulatory requirements are, of course, the most significant. A coal fired power station, for example, may only be required to monitor SO2, NOx and CO emissions, whereas a municipal waste incineration plant will have to monitor other parameters, such as organic compounds, HCl, HF and dioxins and heavy metals.

A recent development in multigas monitoring is the transfer of FTIR technology to the portable instrument sector. This has resulted in a portable analyser that is able to produce laboratory levels of accuracy in the field, for almost any gas. 

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