Glossery

Term Main definition
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.
Pellistor LEL sensor
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
Personal protection
Any equipment, clothing, accessory or instrument that is designed for protection against safety hazards.
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.
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.
Poisoning
What happens when a poison is ingested, injected, absorbed or inhaled. In gas detection, the term refers to rendering a sensor useless by inhibiting its detection principle, without causing a sensor fault. Most sensors can be poisoned by a too high concentration of its target substance. Catalytic Bead LEL sensors are susceptible to poisoning through a too high concentration of combustible gas (e.g. by holding an extinguished lighter to it) and silicons, which coat the catalyst beads, preventing the combusting reaction.
Portable Gas Detection
Any gas detection solution that can be carried single handedly; usually, electronic gas detection monitors that can be held or worn on its user's clothing, belt or around its user's neck through clips and holsters.
Prevention
The action of stopping something from happening or arising. Gas detection can be seen as a preventive measure, in that correctly used gas detection solutions prevent injury, death and damage to process and property. The preferred method of gas detection is very much dependant on the risk that should be mitigated. 7Solutions can advise on the best preventive measures regarding any risk.
Pump
In gas detection, a device that draws an air sample into a detecting agent (colorimetic gas sampling tube or gas detector). Colorimetric gas sampling tubes require a pump, manual or electronic, to draw a sample through them. For electronic gas detectors, pumps can be integrated, clip-on or hand aspirators. Gas detectors with an integrated pump are suitable to sample confined spaces for gas hazards through a sampling hose. Photo Ionisation Detectors (PID) should always be equipped with a pump. A pump generally shortens the response time to gas hazards, but also consume electricity, shortening the battery life.