Gas Sensing Technologies

Hydrocarbon Dew Point Analyzer – Dark Spot

The hydrocarbon dew-point measurement cell uses a patented Dark Spot™ chilled mirror optical technique to measure hydrocarbon dewpoint. Sensitivity of better then 1mg/m3 of condensed hydrocarbons enables the sensor to detect the almost invisible films of condensate which occur at the hydrocarbon dew point.

The optical sensor comprises of a central conical shaped optical surface, specially treated to ensure it only becomes reflective when hydrocarbon condensate is present on its’ surface. This is temperature controlled by a 3-stage thermo-electric cooler, allowing measurements of hydrocarbon dew point up to 55K below the analysers’ operating temperature. The stainless-steel cell assembly allows measurements to be made at pressures of up to 100barg.

During a measurement cycle, hydrocarbon condensate is formed on the mirror, which becomes reflective due to the low surface tension of the condensate. A ring of light forms around the detector due to the conical shape, there is a dramatic reduction in the scattered light intensity within the central Dark Spot™ region. The changing light intensity is monitored and interpreted by the analyser so that When a predetermined layer of condensate has been detected, the instrument records the temperature of the optical surface as the hydrocarbon dew point.

Hydrocarbon Dew-Point Analyzers

Thermal conductivity for binary gas analysis

The thermal conductivity analyser uses the property of thermal conductivity (TC), meaning a gases ability to conduct heat, each gas has a different TC value. The analyser uses this property to measure a gas in another binary sample or pseudo-binary mix.

The analyser uses a pair of thermistors in a Wheatstone bridge configuration. One of the thermistors is in the sample cell while the other is in a sealed reference chamber, as gas enters the sample cell heat is transferred from the thermistor and imbalances the bridge circuit, a current is needed to keep the bridge balanced and from this the TC value of the gas can be determined and from that the proportion of the gas in a sample.

Chromatograph – PED

PST’s Chromatograph uses the Plasma Emission Detection technology that ionizes the sample gas which spectral rays are emitted and detected by an optical system including filter and photodiodes. The emissions vary for each substance allowing the detection of trace level impurities.

Plasma Emission Detector for GCs - LDetek PlasmaDetek 2

Infrared Gas Sensor

PST infrared sensors operate by using nondispersive infrared (NDIR) technology to monitor the presence of a target gas. The sensor contains a long-life tungsten filament infrared light source, an optical cavity into which gas diffuses, a dual temperature compensated pyroelectric infrared detector, an integral semiconductor temperature sensor and electronics to process the signals from the pyroelectric detector.

These NDIR sensors offer fast-response and high-resolution for the detection of hydrocarbons (including methane and propane), carbon dioxide, and nitrous oxide.

The Dynament sensor portfolio also includes a revolutionary Dual-Gas High Resolution Methane/Carbon Dioxide Sensor providing the capability to simultaneously monitor methane and carbon dioxide in a single sensor package while only consuming the power of a single infrared sensor.