Versaperm Limited products

The mass spectrometry (MS) gas detection technique is an accurate and sensitive technique that can be used for any gas.  It is based on ionizing a gas or vapour to generate charged molecules which are excited in an electromagnetic field to determine their mass to charge ratios and identify each component of the gas.   The MS method is widely use due to its high precision and extreme versatility – though the equipment is comparatively expensive.

Semiconductor gas sensors are based around a metal oxide, normally SnO2. When a metal oxide crystal is heated to a certain high temperature, specific elemental molecules are adsorbed by the crystal surface with a negative charge. The sensor can be sensitised to different gases by the choice of operating temperature, microstructural modification and the use of dopants and catalysts. The donor electrons from the surface of the crystal are transferred to the adsorbed oxygen, leaving positive charges in a space charge layer and creating a potential barrier against electron flow. In the presence of a deoxidizing gas, the surface density of the negatively charged oxygen decreases, decreasing the barrier height in the grain boundary. New nanostructure materials are boosting the performance and sensitivity of semiconductor gas sensors due to their much higher surface-to-bulk ratio.

Gas chromatography involves vapourising a sample and injecting it onto the head of the chromatographic column.  A flow of an inert gas (such as nitrogen, helium, argon, or carbon dioxide) carries the sample through the column which contains a stationary liquid phase which is adsorbed onto the surface of an inert solid. An extremely wide variety of gas chromatography detectors can be used depending on the specific case. Non-selective detectors respond to all compounds (except the carrier) and selective detectors respond to individual chemicals or ranges of physical or chemical characteristics. At Versaperm we are not tied to any specific sensor types or manufacturer and so we can always select exactly the right sensor for an application. Versaperm is a world technology leader in the measurement of gas permeability. We offer not only instruments but also comprehensive testing and consultancy services.

Pressure based gas sensor systems use two chambers with the sample under test mounted between. Initially, one chamber is evacuated and the sample gas permeates through from the other chamber. A simple measurement of the gradual pressure change in the evacuated chamber determines the rate of flow across the sample and thus directly measures its permeability. At Versaperm we are not tied to any specific sensor types or manufacturer and so we can always select exactly the right sensor for an application. Versaperm is a world technology leader in the measurement of gas permeability. We offer not only instruments but also comprehensive testing and consultancy services

Electrolytic water vapour sensors are based on a glass capillary tube containing two spiral wire electrodes coated with a thin layer of phosphorous pentoxide. As the gas flows along the tube moisture is absorbed by the phosphorous pentoxide (P2O5) and converted into phosphoric acid. An electrical potential is applied to electrolyze the water, producing hydrogen and oxygen and regenerating the phosphorous pentoxide. The current required by this gives a direct measurement of the mass of the water vapor. At Versaperm we are not tied to any specific sensor types or manufacturer and so we can always select exactly the right sensor for an application. Versaperm is a world technology leader in the measurement of gas permeability. We offer not only instruments but also comprehensive testing and consultancy services.

Infrared gas sensors work by beaming infrared light through a gas sample and measuring the absorption spectrum produced. Many gases, such as water vapour, hydrocarbons and CO2 absorb strongly in the infrared and the frequency of the spectral peak characterises the gas. Typically, the signal produced is compared to reference spectra to identify the gas molecules. However, only one specific absorption region is normally used to determine, quantitatively, the gas concentration. The wavelengths in the infra red region range between 750 nm and 100 µm. At Versaperm we are not tied to any specific sensor types or manufacturer and so we can always select exactly the right sensor for an application. Versaperm is a world technology leader in the measurement of gas permeability. We offer not only instruments but also comprehensive testing and consultancy services.

Capacitive water vapour sensors measure relative humidity (RH) by observing changes in capacitance between conductive electrodes. The sensor works like a plate capacitor with the bottom plate under a thin polymer hygroscopic dielectric. The plate above this allows water vapour to pass throughout polymer until it reaches equilibrium with the gas under measurement. The dielectric strength of the polymer is proportional to the water vapour content and this directly controls its capacitance. A simple temperature measurement allows the absolute humidity to be deduced. At Versaperm we are not tied to any specific sensor types or manufacturer and so we can always select exactly the right sensor for an application. Versaperm is a world technology leader in the measurement of gas permeability. We offer not only instruments but also comprehensive testing and consultancy services.

Impedance water vapour sensors depend upon the absorption of water vapour by a porous non-conducting layer, (the material sample under test), sandwiched between two plate-type conductors. The active sensor layer can be extremely thin and the porous top conductor allows water vapour to flow into the sensor. Simply measuring the impedance of the resulting capacitor gives a measurement of Relative Humidity (RH) which, when combined with the temperature, determines the absolute humidity and thus the number of water vapour atoms in the gas. At Versaperm we are not tied to any specific sensor types or manufacturer and so we can always select exactly the right sensor for an application. Versaperm is a world technology leader in the measurement of gas permeability. We offer not only instruments but also comprehensive testing and consultancy services.

Thermal conductivity gas analysers are based on measuring the thermal conductivity of a gas such as hydrogen, helium or carbon dioxide and comparing it to a known reference sample using an identical thermal conductivity sensor. The sensors incorporate an extremely sensitive element with low thermal capacity. The difference in the two conductivities is a direct function of the number of atoms of the gas in the sample. Thermal conductivity sensors are highly reliable, accurate, maintenance free and little, or no, calibration is required.

Flame Ionization detectors can be extremely accurate and are used to measure concentrations of hydrocarbons and other solvents within a gas. They are detected by burning them in an air-hydrogen flame - which creates high and precisely measurable levels of Ionization. The ionization occurs as a result of heating the carbon atoms present in the sampled gas and its level is directly proportional to the number of carbon atoms in the sample. An electrostatic field is set up around the burner making the ions flow to the collector, and the electrons flow towards the burner. The current created provides a direct measurement of the Ionization. At Versaperm we are not tied to any specific sensor types or manufacturer and so we can always select exactly the right sensor for an application. Versaperm is a world technology leader in the measurement of gas permeability. We offer not only instruments but also comprehensive testing and consultancy services.