Hydrogen Sulfide (H2S) is a flammable, poisonous gas with characteristic odor of rotten eggs,perceptible in air at concentrations of 0.001 to 0.1ppm, with a sweetish taste. It burns in airwith a pale blue flame, ignites at 260°C. Its explosive limits when mixed in air are: lower limitLEL = 4.3% upper limit UEL = 46%. The gas which is abundant in oil & gas explorations,particularly in crude oil cuts, is processed at various refineries and petrochemical facilities wherededicated "desulphurization" processes produce it from organic sulfur compounds. The H2S gasis heavier than air and accumulates in low places, thus posing major health hazard to humans.
TLV = 10 ppm (14mg/m3).
The most advanced and reliable H2S gas detection method is the optical open path remotesensing technique. The method relies on the specific "finger print" absorption characteristicof H2S in various spectral bands. In the UV band H2S gas has a typical strong absorption inthe solar blind range of 189 nm up to 270 nm that enables its fast and reliable detection at lowconcentrations of 1-5 ppm. In the IR band the H2S gas has additional typical absorption peaks at1-2 µ, 3.72µ and 3.83µ however at high concentrations of gas and "noisy" spectral background,facts that make it not advantageous for fast and reliable detection.
The Safeye Open Path Gas Detector model specifically designed for detecting H2S at very lowconcentrations in the air features a unique UV channel .
The early detection of H2S at concentrations of up to 10 ppm is essential in order to prevent itstoxic influence on humans. The optical open path detection method is the latest development formonitoring low concentration of hydrogen H2S in the air.
Ethylene is a highly flammable hydrocarbon gas employed in many industrial processes. Thegas is produced by refining crude oils. The plastics and polymer industry use ethylene as theirmain "building-block" for producing longer polymers with special characteristics due to thefunctional groups attached to the ethylene backbone.
Ethylene has a unique infrared spectral absorption, due to its "double-bond" chemical structure,which when compared to standard linear hydrocarbons (paraffin and olefin) exhibits a spectralshift that requires a special filter.
A specially designed Safeye open path gas detector model is capable of detecting the ethylenegas in air at concentrations well below its flammable limit, at 0-2 LEL*m.
The building block of many plastics and polymers, ethylene gas, has a unique spectral finger printthat requires a special spectral analysis in order to detect it by optical gas detectors.
