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Advanced technologies for monitoring and analysis to help deliver reliable results over a wide range of gases and particulate concentrations
Depending on the type of gas and particulates targeted for monitoring and the data output desired, various technologies have been proven to effectively analyze ambient air and detect its components. We offer a wide range of products that utilize these technologies to help enable more reliable air quality monitoring for your operation.
Beta attenuation
When beta rays strike a material, they can be absorbed, reflected or pass directly through. The attenuation of intensity in beta rays is proportional to the amount of material present. The attenuation through most materials is relatively consistent and is based on the electron density of the material (calculated by dividing the atomic number by the atomic mass). The attenuation for most materials is about 0.5, except for hydrogen and heavy metals.
The principle behind beta attenuation particulate sampling instruments (beta gauge) is that energy is absorbed from beta particles as they pass through particulate matter (PM) collected on a filter media. Beta gauge instruments have been designed to take advantage of this scientific principle to monitor/measure particulate matter (PM) concentrations. The attenuation due to only the PM is measurable if a baseline beta count through just the filter can be established prior to sampling. The difference between the baseline beta count and the beta count after sampling is directly proportional to the mass of PM in the sample.
The two main components of a beta attenuation measuring system are the beta source and the detector. The beta source must be selected so that: it has an energy level high enough for the beta particles to pass through the air volume, collection media (i.e., the filter tape) and the particulate; it has enough source material so that a high count rate is present; it is stable over long periods of time; and it does not present a danger to the health of personnel that come into contact with the instrument. The source of choice has been carbon-14 because: it has a safe yet high enough energy level; it has a half-life of 5,568 years; and it is relatively abundant. Many different types of detectors can quantify beta particle counts, but the ones most widely used are the Geiger Mueller counter or a photodiode detector.
Chemiluminescence
When combined, certain gases produce high energy chemical reactions that emit light energy (photons), known as chemiluminescence. Specifically, light emission results when electronically excited molecules decay to lower energy states. These emissions are detected by photomultiplier tubes and, by measuring the intensity and characteristics of the light emitted, the presence and concentration of various gases can be accurately determined. Our analyzers that operate using this principle employ advanced optical technology for high sensitivity and reliable readings. Explore them here:
Gas Chromatography (GC)
Gas chromatography (GC) is a proven analytical tool that was initially developed in the 1950s and is now a widely applied technique for separating and analyzing compounds that can be vaporized without decomposition. Because GC is best used to measure volatile compounds and utilizes gas columns that are stable and long lasting, GC is ideal for certain gas measurement applications. Explore instruments that use GC here.
Gas Filter Correlation (GFC)
Gas Filter Correlation (GFC) is a form of Nondispersive Infrared detection. Like NDIR, GFC operates on the principle that carbon monoxide (CO) absorbs infrared radiation at a wavelength of 4.6 microns. Filtering isolates the detected wavelength range to that of the gas target. Because infrared absorption is a non-linear measurement technique, it is necessary to transform the basic analyzer signal into a linear output. The analyzer uses an exact calibration curve to accurately linearize the instrument output over any range up to a concentration of 10,000ppm.
Gas scrubbing
Gas scrubbing technology combines filtration, catalytic conversion, and oxidation to produce pollutant free air (Zero Air) from ambient air. Zero Air is then used for instrument calibration and as diluent air supply for spanning ambient air analyzers. Gas scrubbing technology removes NO, NO2, O3, SO2, CO, and hydrocarbons. Our gas scrubbing technology passes pressurized air into a column of Purafil (potassium permanganate on alumina) which oxidizes NO to NO2. From there the air passes through a column of activated charcoal which removes NO2, SO2, O3 and hydrocarbons. Lastly, the air is moved into the reactor where it is heated to 350°C over a catalytic surface which converts CO to CO2 and any remaining hydrocarbons, including methane, to water and CO2. This process results in a pollutant free stream of air.
Non-Dispersive Infrared (NDIR) technology
The relative simplicity of NDIR technology provides precise, long-term gas analysis while lowering operating cost throughout the life cycle of the instrument. NDIR analyzers operate on the principle that gases absorb radiation in specific infrared wavelength ranges. As infrared light passes through a container of gas, a non-dispersive infrared sensor detects how much of the filtered light wavelength the gas absorbs. A measurement of gas concentrations is obtained. Thermo Scientific analyzers combine this technology with advanced optical filters to enable even more precise measurements.
Optically Enhanced Fourier Transform Infrared (OE-FTIR)
Optically Enhanced Fourier Transform Infrared (OE-FTIR) using breakthrough StarBoost Technology enables commercial FTIR gas analysis that dramatically increases sensitivity, linearity and dynamic range over narrow spectral bands of interest. It utilizes specialized optics, electronics and analysis algorithms to go beyond traditional FTIR gas analysis capabilities.
This enhancement technology, proven in demanding applications such as ethylene oxide and formaldehyde measurement, enables users to achieve single-digit ppb detection limits for many applications. It can be supplied as a turnkey add-on to the Thermo Scientific MAX-iR Gas Analyzer and is compliant with several regulatory methods including US Environmental Protection Agency (EPA) method 320 and American Society for Testing and Materials (ASTM) D6348.
Gravimetric
Gravimetric technology is a quantitative method used to determine concentration or amount of a substance by measuring its mass. Our Partisol samplers uses this technique to accurately measure particulate matter in the ambient air for air quality assessment. Partisol samplers are specially designed instruments that capture airborne particles on filter media for subsequent analysis. This technique is widely used in environmental monitoring and regulatory compliance to measure concentrations of particulate matter, which can have significant health and environmental impacts.
Key components and functionality
- Sampler unit: The partisol sampler consists of a housing that contains the sampling components, including a pump, flow controller, and filter holder. The unit is typically placed in a fixed outdoor location to continuously sample ambient air.
- Filter media: Air is drawn through a filter, usually made of materials like Teflon, quartz, or glass fiber, which captures particulate matter. The filter can be designed to collect different sizes of particles, such as PM10 (particles with a diameter of 10 micrometers or less) or PM2.5 (particles with a diameter of 2.5 micrometers or less).
- Flow control: The sampler includes a flow control system to ensure a consistent and accurate flow rate of air through the filter. This is crucial for obtaining reliable data on particle concentrations.
- Data logging: Modern partisol samplers are equipped with data logging capabilities to record sampling conditions, such as flow rate, temperature, and humidity, ensuring accurate and comprehensive data collection.
Sampling process
The partisol sampler is set up at the monitoring site, with the filter installed in the filter holder. The sampler is programmed to operate at a specific flow rate and sampling schedule. Air is then drawn through the filter over a specified period, typically 24 hours, capturing particulate matter on the filter surface. After the sampling period, the filter is removed and sent to a laboratory for analysis. In the laboratory, the filter is weighed to determine the mass of particulate matter collected. Additional analyses, such as chemical composition or elemental analysis, can be performed to identify the types of particles present.
Pulsed Fluorescence technology
Our Pulsed Fluorescence analyzers operate on the principle that H2S can be converted to SO2. As the SO2 molecules absorb ultraviolet (UV) light and become excited at one wavelength, the molecules then decay to a lower energy state emitting UV light at a different wavelength. The pulsing of the UV source lamp serves to increase the optical intensity and a greater UV energy throughput and lower detectable SO2 concentrations are realized.
Because this technology uses reflective bandpass filters, which are less subject to photochemical degradation and are more selective in wavelength isolation than transmission filters, increased detection specificity and long-term stability are achieved.
SHARP technology
Thermo Fisher Scientific SHARP technology couples light scattering measurement with beta attenuation to provide precise and accurate data. It starts with the proven method of using beta attenuation to determine the mass of the collected sample and adds a nephelometer to increase the overall performance.
The nephelometer uses light scattering that is fast and precise in measuring the particle count, and the nephelometer count readings are converted to a “raw” mass concentration based on an internal algorithm and initial factory calibration using a standard aerosol. While this calibration allows the nephelometer to provide mass concentration results that are accurate for the specific calibration aerosol at the time of manufacture, the calibration aerosol may not represent the actual sampled aerosol which can result in a measurement bias compared to the true mass readings. To compensate for this potential bias, the SHARP compares the nephelometer concentration with the beta measured concentration and adjusts the nephelometer concentration to match the concentration reported using the beta attenuation technique. The adjustment is performed continuously and reported in real-time. This results in a reported SHARP value that has high accuracy and high precision.
Tapered element oscillating microbalances (TEOM)
Particulate matter monitoring systems that employ tapered element oscillating microbalances (TEOM) technology are “gravimetric” instruments that draw (then heat) ambient air through a filter at a constant flow rate, continuously weighing the filter and calculating near real-time mass concentrations of particulate matter.
The TEOM monitor technique relies upon an exchangeable filter cartridge seated on the end of a hollow tapered tube. The wider end of the tube is fixed. As the air passes through the filter, particulate is deposited. The filtered air then passes through the tapered tube to a flow controller. The tapered tube with the filter on its end is maintained in oscillation in a clamped-free mode. The frequency of oscillation is dependent upon the physical characteristics of the tapered tube and the mass on its free end.
As particulate deposits land on the filter, the filter mass change is detected as a frequency change in the oscillation of the tube. The mass of the particulate matter is thus determined inertially, i.e. directly. When this mass change is combined with the flow rate through the system, the monitor yields an accurate measurement of the particulate concentration in real time. The major advantage of this method is that any changes in aerosol characteristics will not influence the accuracy of the mass measurement.
1405 TEOM-D
UV photometry
UV photometric gas analyzers take advantage of the fact that certain gases exhibit a pronounced absorption band in the spectral range of 200nm to 400nm. Because of the high absorption behavior of the gases in specific bands, analyzers that use UV photometry can reliably detect very low concentrations of target gases. Additionally, results using this method are resistant to interference from the presence of water vapor and carbon dioxide. This technology is also advantageous in that additional optical spectrometers or filter elements are not required.
Explore analyzers that use UV photometry:
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