| 1. Ambient |
| Refers to the normal conditions of the air around you. |
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| 2. Blowback |
| A periodic high pressure air pulse to clean the particulates out of the filter, to prevent it from clogging. |
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| 3. CEMS |
| Continuous emissions monitoring systems [generally refers to EPA compliant systems. |
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| 4. Chemiluminescence |
| Specific analyzer type often used for NOx measurements. |
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| 5. Combustibles |
| Materials that will burn [react with O2 to liberate heat] CO, CxHy, H2 and etc. |
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| 6. Control Panel |
| The Oldham-supplied receiver for detector output signals. Control Panels contain various features such as digital readings display, audible and visual alarms, etc. |
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| 7. Detector |
| Also called a "transmitter". The field-mounted (or hand-held) device consisting of an enclosure, the sensor, and electronics which converts the basic signal coming from the sensor into a usable analog output signal (typically 4-20 ma). May be used as a stand-alone instrument, or with an Oldham-supplied Control Panel, or with any customer-supplied device which is capable of accepting the detector’s analog output signal. |
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| 8. Dilution |
| System design where the sample is diluted with clean air to lower temperature and to lower water concentration below the dew point. |
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| 9. DIR |
| Dispersive infrared analyzer. It records an absorption spectra which can be saved, as well as analyzed for specific gases |
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| 10. Extractive |
| Syetem design where a sample is extracted from the process before measuring. |
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| 11. FID |
| Flame ionization detector for measuring VOCs and/or total hydrocarbons |
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| 12. Fluorescence |
| One of the measurement techniques used for analysis of SO2. |
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| 13. FTIR |
| Fourier transform infrared analyzer records the fourier transform of the absorption spectra, which can be mathematically converted to an absorption spectra, which can be saved as well as analyzed for specific gases. |
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| 14. In-Situ |
| System design where the measurment is made in place without extracting a sample. |
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| 15. Lower Explosive Limit (LEL) |
| The LEL of a flammable gas is the minimum concentration of that gas, at normal ambient conditions, at which it will burn if there is a source of ignition present. At a concentration below the LEL, the gas will not burn. Gas detectors for flammable gases are typically calibrated in the range 0-100% LEL. The term Lower Flammable Limit (LFL) is less commonly used, and means the same thing. The actual concentration of the LEL varies from one gas to the next and is determined empirically by laboratory experiment. |
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| 16. NBPF |
| Narriw band-pass filters. An optical device for NDIR wavelength selection. |
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| 17. NDIR |
| Non-dispersive infrared analyzer, tuned to measure one or more specific gases. |
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| 18. NDUV |
| Non-dispersive UV analyzer, tuned to measure one or more specific gases. |
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| 19. NEMA 12 |
| An encloseure designed for indoors location. |
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| 20. NEMA 4 |
| An encloseure designed for outdoors location. |
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| 21. NOx |
| Name given to the sum of NO and NO2. |
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| 22. Opacity |
| Generally measured only in North America; a measure of dust level by measuring the reduction in light transmission [80% transmission is 20% opacity] |
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| 23. Open-Path |
| An instrument that projects a beam through the open air [along the fenceline, across the-road, or in the workplace, for example] |
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| 24. Paramagnetic |
| Specific analyzer type often used for measuring oxygen [O2] |
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| 25. Permeation Dryer |
| A membrane that removes only the water vapor. |
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| 26. Quenching |
| A process that creates an interference to the chemiluminescence NOx measurement. |
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| 27. Remote |
| Measurement from a distance, such as remote sensing of vehicle exhausts. |
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| 28. Sensor |
| The actual device which "interacts" with the gas to initiate the measurement of its concentration. Many customer refer to a "sensor" when they really mean an instrument (detector, transmitter, etc.). Oldham does not sell sensors, except as spare parts. |
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| 29. Stratified |
| Many gas streams are not homogeneous in composition, but may contain concentration gradients or strata. |
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| 30. TDL |
| Tunable diode lasers used as a narrow line source for near IR measurements. |
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| 31. Thermal Conductivity |
| Specific analyzer type often used for measuring hydrogen [H2]. |
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| 32. Threshold Limit Value (TLV) |
| For a toxic gas, the TLV is the time-weighted eight-hour maximum exposure [in ppm] considered safe for humans. In other words, a worker can safely be exposed to the concentration of a toxic gas equal to the TLV for eight hours per day. |
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| 33. Upper Explosive (Flammable) Limit (UEL/ UFL) |
| The UEL is the maximum concentration of a flammable gas at ambient conditions at which the gas will burn if there is a source of ignition present. At a concentration above the UFL the gas will not burn. The UEL is of no direct concern in the field of gas detection. The detectors do not reach this range. |
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| 34. VOCs |
| Votatile organic compounds [generally referring to receiver compounds] . Requires FID & Zirconium oxide O2 analyzer. |
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