Accumulation of gaseous substances at the surface of substrates.

Is air taken from the engine or auxiliary power unit to maintain a constant air pressure in the cabin, supply the cabin with fresh air and as a de-icing medium.

In connection to the pattern recognition, it seeks to assign a pattern to one or more measurements. The categorization can be of arbitrary nature, also possible are concentration groups or patterns from known substances or mixtures.

Chemical warfare (CW) involves using the toxic properties of chemical substances as weapons to kill, injure, or incapacitate an enemy. The offensive use of living organisms or their toxic products is not considered chemical warfare but biological warfare. (source: en.wikipedia)

Opposite procedure to Adsorption, i.e. the accumulated materials are released e.g. by heating (thermal Desorption).

It indicates the lowest limit concentration to which a determined measurement instrument is still able to retrieve a signal. The instrument PEN is able to measure substances in the ppm range and through the complementary use of an EDU it is able to increase the detection to the ppb range.

The Electrochemical Cell sensor measures the electric current changes within an electrolyte. These changes in the electric current are caused by the depositing or releasing of certain substances on the surface of the sensor. Since only determined substances can provoke this electric current alteration, it is easy to understand which substance was detected.

Enrichment and Desorption Unit, also named as Thermal Trap and Desorption (TTD). The EDU will help adsorbing substances on a substrate and then releasing them by thermal desorption. Since desorption and/or release takes place in a very short period, it originates a brief increase of the concentration which is used to increase the detection limit from the measuring instruments.

ETW is the abbreviation for the german word "Einsatztoleranzwerte" and it concerns a list of chemical substances and the related concentration limits regarding the maximum exposure concentration that a human being can withstand for a period of 4 hours without having any injury or long-lasting health impairments.

Gas Detector Array, a portable gas detector system for monitoring the environmental air. A gas detector detects and analyses the composition of the air.

An ion mobility spectrometer is equipment which, roughly explained, measures the acceleration behavior of ions through an electrical field. To carry out such a measurement, ions are accelerated and measured along the electrical field, and it is observed how much time each ion needs to travel a defined path. Since ions of different materials are differently heavy, they exhibit also a different acceleration behavior. Based on the flight time it is possible to take conclusions on the detected substances.

The Metal Oxide Sensor is a solid sensor, which - as the name already says – uses a metal oxide as sensor material. From the contact of substances with the surface of the sensor results oxidation and/or reduction procedures which on its turn leads to a measurable change of the sensors’ conductance. Depending on the base material and the working temperature, different sensors react differently to different substances.

Oil smell from the engines during normal air traffic or during startup which is transported in the bleed air into the cabin. This leads often to an excessive exposure of passengers and crew. The oil odor often contains harmful Tricresyl phosphate (TCP).

Pattern recognition – First of all a determined pattern from a determined substance is taken. Afterwards, the measurement is compared with the obtained pattern and the “similarity” is established by using different methods. Therefore it is possible to match the respective measurement with the corresponding pattern.

Portable Electronic Nose - also known as E-Nose.
An electronic nose is a device intended to detect odors or flavors.

The Photo Ionization Detector ionizes the atoms of a gaseous substance by means of a strong UV light. The ions carry directly a measurable electric current, which allows taking conclusions on the substance. Aside from the substance’ identification, the photo ionization detectors are also particularly interesting for the determination of the concentration, since they work within a wider linear range.

Parts per million express, how many parts of a substance can be found in one million particles within a total mixture. It is thus a measurement unit for the concentration of a substance. Derived units are ppb (parts per billion), ppt (parts per trillion), percent (one hundred) and Parts per Thousand (1 thousand).

Determination of the quantity of a substance. With gases the portion of a substance is often determined from the total mixture. (like ppm), being that also other definition of portioning are possible, like for example, smell units.

RS232 is a standard for serial communication which allows two different instruments exchanging their data. Data will be transmitted through two serial lines. RS232 is standard in many measuring’ instruments, however it is increasingly being replaced by the USB which is faster.

Describes the response characteristics of a sensor related to different compounds. The higher the selectivity the smaller is the number of compounds that a sensor can generate signals for. The smaller the selectivity the wider is the spectrum of compounds that a sensor reacts to.

Describes the composition of different sensors integrated in a single module, able to carry out simultaneous measurements, for example, from a gas. The different signals from the sensors are used, for example, to better distinguish substances and to increase the detection range of the system.

TCP (Tricresyl phosphate) are a group of chemical compounds, which occur in a number of different isomeric forms and are used as additives in airplane oils. They are phosphate esters of cresols. Many isomers are neurotoxins. Exposure to these substances often leads to health problems.

Toxic Industrial Chemicals are toxic compounds usually used in (chemical) industries.

Standard interface which allows data exchange from instrument to computer. Differently from the RS232, the USB cable allows that more instruments exchange their information. Besides the USB is significantly faster than the RS232.

Wireless local area network is a network through which different instruments are able to communicate with each other. Depending on the actual environment, the distance for data tranmission can surpass 150 meters. WLAN is already standard delivered in portable devices such as notebooks or mobile phones/Smartphones.