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Laminar Flow: Characterized by the gliding of concentric cylindrical layers past one another in orderly fashion. Velocity of the fluid is at its maximum at the pipe axis and decreases to zero at the pipe wall.
LASER: is an acronym for light amplification by stimulated emission of radiation. Lasers are devices that amplify light and produce coherent light beams, ranging from infrared to ultraviolet. A light beam is coherent when its waves, or photons, propagate in step with one another. Laser light, therefore, can be made extremely intense, highly directional, and very pure in color (frequency).
Laser Gas Detector: A gas detector that employs a laser diode attuned to the absorption curve of a specific gas such as methane. In a gas sample containing methane, a portion of the diode-emitted light wave will be absorbed and can be directly quantified as to the presence in PPM of methane gas.
L.E.L.: In terms of leak detection, this is the abbreviation for Lower Explosion Limit. For methane gas, 100% of the LEL would equal to a gas concentration of 5% gas volume in a given sample. In French, the term would be L.I.E. or Limit Inferior Explosive. The LEL is the smallest amount of gas that will support a self-propagating flame when mixed with air or oxygen and ignited. In gas detection systems, the amount of gas present is specified in terms of % LEL; 0% LEL is a combustible gas-free atmosphere, with 100% LEL being an atmosphere in which the gas is at its lower explosive limit. The relationship of % LEL and % by volume differs from gas to gas. Typical settings for an alarm circuit are 20% LEL for the low alarm and 50% for the high alarm. The LEL of a gas is affected by the temperature and pressure; as the temperature increases, the LEL decreases and hence the explosion hazard increases. Approximately 1 atmosphere of pressure increase usually lowers the LEL. The LEL of a gas is not significantly affected by the humidity fluctuations normally encountered in the operation of a gas detection system.
Localization: In leak detection, this term is used in connection with actually determining the location of a gas leak.
LOCK-O-RING® Flange: A special TDW flange designed for STOPPLE® plugging operations. It receives the LOCK-O-RING® plug and allows recovery of the valve and hot tapping and plugging equipment.
LOCK-O-RING® Plug: The "completion plug" that works with LOCK-O-RING® flanges. Installing the LOCK-O-RING® Plug allows recovery of valves and equipment.
LOCK-O-RING® with Guide Bar: Used in place of a LOCK-O-RING® Plug when product flow is desired through the plug, fitting and valve through the branch pipe. The valve will be left on the fitting.
AB - CD - EF - GH - IJ - KL - MN - OP - QR - ST - UV - WX - YZ
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