The right sensors for gas analysis
Gas Analysers and their sensors
MAT1100 | MAT1200 | MAT1400 | MAT1500 | |
---|---|---|---|---|
AREA OF APPLICATION | Sporadic
O2-sample check | Combined
O2- and CO2-measurement | High sample throughput
High O2-concentration | High sample throughput
High O2-concentration Combined O2- and CO2-measurement |
ADVANTAGES | Cost-effective option
Fast operational readiness Low drift | Cost-effective option
Low drift Environmentally compensated CO2 measurement | Long service life
Fast measurement High precision with the lowest O2-concentrations Wide measurement range Drift-free | Long service life
Fast measurement High precision with the lowest O2-concentrations Wide measurement range ZrO2: drift-free, NDIR: low drift Environmentally compensated CO2-measurement |
O2-SENSOR | EC | EC | ZrO2 | ZrO2 |
CO²-SENSOR | NDIR | NDIR | ||
N² | Arithmetic determination | Arithmetic determination |
Electrochemical oxygen cell (EC)
The measurement range of the electrochemical oxygen cell between 0.5 and 35 volume per cent O2 makes it especially interesting for products such as fresh fruit, raw, low-fat fish or sea food, which are packaged neither under an oxygen-free nor particularly oxygen-rich modified atmosphere. Since this low-cost measuring cell is quickly ready for use, it is recommended for sporadic sample checks or if only a few samples are measured every day. The low-drift long-life cell in our MAT1100 and MAT1200 devices boasts an above- average service life of up to six years. Unlike conventional alkaline cells, it uses an acidic electrolyte (formic acid), which is why its cross-sensitivity toward acidic gas components such as carbon dioxide is low (< 0,002 vol.-% O2 with a load of 100 vol.-% CO2) , and a measured value correction as a functionan of the CO2 concentration is not required. Carbon monoxide from coffee packaging or flammable gas components such as alcohol also have no influence on the specified accuracy.
Design and functionality of the zirconium dioxide sensor (ZrO2)
Because of its excellent accuracy of ±0.001 volume per cent with the lowest O2 concentrations, the zirconium dioxide sensor is primarily used to test oxygen-free modified atmospheres for sterilised finished products or electronic, pharmaceutical or cosmetic products. Thanks to its wide measurement range between 0 and 100 volume per cent, it can also be used for high oxygen concentrations as required for red fresh meat. The investment in the zirconium dioxide sensor of the MAT1400 and MAT1500 devices will quickly pay off if many samples are measured every day due to the long service life of up to 15 years. Thanks to the fast response time of 0.3 seconds, only very little sample gas is required – an advantage especially in case of a small headspace volume as it is common with sachets and cosmetics products. The cross-sensitivity of the sensor toward humidity and temperature is low. A regular adjustment is not necessary because it is free of drift. We simply recommend an occasional calibration with synthetic air.
Inside the sensor, a ZrO2membrane heated to 750 °C separates the sample gas from the ambient air. Due to the Yttrium oxide stabilisation of the membrane, oxygen ions diffuse in the direction of the lower oxygen partial pressure and hence to the lower oxygen concentration. Both sides of the membrane are coated with a platinum film permeable to gas. These electrodes allow you to measure an electrical potential difference between the sides of the membrane from which the oxygen concentration of the sample gas can be calculated.
Non-dispersive Infrared sensor (NDIR)
From poultry with skin to cut cheese to cakes and pasties – the non-dispersive infrared sensor, with its wide measuring range of 0 to 100 vol%, is suitable for most applications of carbon dioxide in protective atmospheres. Its high accuracy of ± 0.5 Vol .-% always ensures accurate measurement results. The NDIR sensor operates according to a patented process that uses two wavelengths of the infrared spectrum in order to automatically compensate for temperature, humidity and other environmental influences. Since it does not have any moving parts, it is very reliable, and no additional maintenance work is required. The NDIR sensor of the MAT1200 and MAT1500 models can be very easily adjusted via the intuitive user interface, but thanks to the low drift this is rarely necessary.
Flow rate monitoring and temperature control
In support of the sensor technology, our gas analysers measure further values in order to ensure the absolute reliability of the measured values related to the protective gases. For example, the flow rate of the sample is determined so that optimum measurement results are always guaranteed regardless of tube length, contaminations in the filter and similar application conditions. If the additional automatic monitoring of the gas flow is activated, a warning will appear if the flow rate does not reach the value set by the user. The temperature of the zirconium dioxide sensor of the MAT1400 and MAT1500 models is kept at 750 °C regardless of the sample temperature as it operates most efficiently by this means.