Term Main definition
Photo Ionization Detector (PID)
A detection principle for volatile organic compounds that is based on the ionization of substances by ultra violet light. The lamp's ability to ionize compounds is expressed in electronvolts (eV), just as the ionizing potential of a compound. A compound is detectable by the PID sensor if its ionizing potential is lower than the ionizing ability of the lamp. Just like a LEL sensor, a PID sensor is a wideband monitor, meaning that it doesn't identify substances, just the presence of one or more of a group of substances. This ability can still hold tremendous value for workers that know it's limitations and idiosyncracies, for which 7Solutions gives many training courses. Many PID instruments and multi gas instruments with PID options are available. 7Solutions can advise the optimal PID instrument for every situation.
Phosphine, (PH3)
A highly toxic, flammable gas that is odorless in its purest form, although the usual presence of substituted phosphine and diphosphane give it a highly unpleasant odor, while the presence of diphosphane may make it spontaneously flammable in air in sufficient quantities. Phosphine is used in pest control, especially in transportation, where it is the only fumigant that is allowed, cost-effective, rapidly acting and does not leave residues in the stored product. Phosphine is detectable with colorimetric gas sampling tubes, while many manufacturers carry electrochemical phosphine sensors.
Personal protection
Any equipment, clothing, accessory or instrument that is designed for protection against safety hazards.
Permissible Exposure Limit (PEL)
A legal limit for exposure of an employee to a chemical substance or physical agent, such as high level noise. For chemical substances, usually expressed in TWA (time-weighted average, usually for 8 hours), STEL (short-term exposure limit (usually a 15-minutes average) and ceiling values that may not be exceeded at any time. The unit of measurement is usually ppm (parts per million) or
Pellistor LEL sensor
Parts per Million (ppm)
One of two common units of measurement for small concentrations of substances in another substance, the other being mg/m3. When the molecular mass of a substance is known, a threshold expressed in mg/m3 relatively easy to convert. In some science settings, mg/m3 is preferred, while almost all gas detection equipment's measurement values are expressed in ppm by default.
Oxygen, (O2)
A highly reactive nonmetal, oxidizing agent that readily forms oxides with most elements as well as with other compunds. Oxygen accounts for approximately 20.9% of the volume of the atmosphere. While essential to aerobic (oxygen-depending) life forms, a high concentration of oxygen constitutes a severe fire and explosion hazard of even normally non-burning materials. This is the reason that instruments that contain an oxygen sensor warn for lower concentrations (as these present a choking hazard) and higher concentrations (as these present a fire hazard). Apart from dedicated sensors, oxygen is detectable with a vast range of colorimetric gas sampling tubes.
Oxidizing Agent
A substance with the ability to oxidize other substances. Common oxidizing agents include oxygen, hydrogen peroxide and the halogens.
Organic Compound
Generally, a substance that includes carbohydrates.
Occupational Safety and Health Administration (OSHA)
A US Department of Labor agency that sets the standards for safe and healthy work environments. It also enforces these statutes and regulations in the US and provides education, training and assistance to companies and organizations.
Nanometer (nm)
A measurement of length that equals 1 x 10-9 meters, or 1/1,000,000th of a millimeter.
Multi gas detection
Any electronic system that can monitor and alarm for more than one target gas simultaneously. Usually, Multi gas detectors can be equipped with many combinations of different sensors, of which oxygen and LEL sensors are usually two. Some multi gas detectors can also contain a Photo Ionisation Detection (PID) sensor, a CO2 sensor or some other specialty sensor. They are equipped with a battery, alarm functions and communication, either to transfer detected values to a computer or to transfer real-time readings to a central monitoring location. A tendency is taking place to miniaturize "simple" multi gas detectors and to add ever more functions to more complex and costly multi gas detectors. 7Solutions has mixed experiences with most of these devices and can give you a great advice for what to look for in your next gas detector.
To observe and check progress or quality of something over a period of time, to keep under systematic review. In gas detection, this pertains to a device that monitors the concentration of its target substance in real-time, notifying its user when the detected concentration falls outside preset thresholds. All portable gas detectors with few exceptions fall into this category, which means the number of gas monitors is vast. Monitors can have subtly different characteristics as to their monitoring specifications, making it important to obtain expert advice as to which monitor to use in specific situations. 7Solutions, with its decades of experience in every gas detection situation imaginable, is ideally placed to provide this advice.
Molecular Mass
The mass of a given molecule, expressed in Daltons, the unified atomic mass unit. The unit is chosen so that a mole of a substance (6.02214076
The SI unit for amount of substance, defined as 6.02214076
Micrometer (
A measurement of length that equals 1 x 10-6 meters, or 1/1,000th of a millimeter.
Methane, (CH4)
Geiger counters and X Ray Fluorescence detectors make use of methane when used in combination with argon. Methane, (CH4) CAS #74-82-8 UN1971; UN1972, can also be put into a mixture with hydrocarbons when looking for the PCI of coal or hydrocarbons. In this use, it is a reference point for measurements that are calorimetric. Other uses of methane include calibration, monitoring, and analyzing in various petrochemical and environmental industries.
Measuring heads
In gas detection, sensor units.
Measuring cases
Any system in a case that forms an integrated solution for a fixed set of circumstances or a fixed measurement need.
Measurement and control technology
Any piece of equipment that is designed to measure certain parameters and to take action upon the measurement results, usually when controlling (production) processes. Gas detection, in various degrees of specialty, form an important group of measurement instruments on which control actions are based.


7Solutions has its own service and maintenance department where we can service any gas detection instrument, no matter what brand or age.

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