Terms starting with L

The number of operating hours until an LED product's light output falls to 70 percent of its initial value.

To connect the air hoses between cars and open the angle cocks so the brake pipe runs through. Shop talk

Weld metal that failed to fuse with the base metal or a previous pass at some boundary.

The soft, chalky skin of fines that bleed water leaves on top of concrete, too weak to bond to.

A weak, powdery skin of cement and fines on the surface of concrete that sealants and membranes cannot hold onto.

A single wavelength channel on a fiber, named after the Greek letter used for wavelength. Shop talk

Shorthand for an optic flat to one tenth of a wavelength, used to mean good-quality laser optics. Shop talk

Oil film thickness divided by combined surface roughness, showing how well the lubricant separates the teeth.

Oil film thickness divided by the combined roughness of the two surfaces, used to judge the lubrication regime.

Sheet of reinforced resin, usually clad with copper foil, that rigid printed circuit boards are built from.

Joining a nonwoven to film, another nonwoven or other material to make one multilayer product.

The trade word for a replaceable light source, what consumers call a bulb, as distinct from the fixture it goes in.

To terminate a conductor on a breaker, lug, terminal or device. Shop talk

Shop word for the flat root face left at the bottom of a bevel, called the root face in codes. Shop talk

A bonded joint where two parts overlap face to face, loading the adhesive mainly in shear.

The standard strength test for adhesives, pulling apart a single overlap joint and reporting load over bond area.

Running a matched bevel or hypoid pair together with abrasive compound after heat treat to refine contact.

To produce laser light, as in the cavity is lasing or it won't lase below 2 amps. Shop talk

A semiconductor laser driven by electric current, used as a light source in its own right and to pump other lasers.

Shop clipping of backlash, the free play between mating gear teeth, as in set the lash or check lash. Shop talk

The pump level at which gain exactly balances resonator losses and laser output begins.

Lowest Astronomical Tide: the lowest level that tide predictions reach when the weather is held at average.

A time delay between when a sensor measures something and when that measurement gets its time stamp.

Heat tied up in moisture, added or removed when water evaporates or condenses without changing air temperature.

Water-based polymer dispersion used as the binder in chemically bonded nonwovens.

A long reference fiber placed between the OTDR and the cable under test so the first connector can be measured.

The first-order formula that combines input standard uncertainties, weighted by sensitivity coefficients, into the output uncertainty.

Protecting an idle boiler from internal corrosion during an outage or the off season.

How far astern of its tow point a towed sensor actually rides, measured horizontally.

A long, soft, yellowish flame that drifts and licks the furnace walls instead of burning crisp and compact. Shop talk

L-shaped conduit body with its outlet on the back, used to turn a conduit run straight through a wall.

Lucent Connector: the small latching connector with a 1.25 mm ferrule used on most transceivers and data center panels.

Limiting condition for operation: a technical specification requirement for equipment or conditions needed to run the plant.

The distance a thread advances along its axis in one full turn, equal to pitch times the number of starts.

A marked line with a lead weight on the end, used to measure depth by hand and to check echo sounders.

To test a system or a joint for leaks, usually with a helium leak detector, after any break of vacuum. Shop talk

Drainage layer between the primary and secondary liners of a double liner that collects and reveals leakage.

Quantity of gas entering a vacuum system through a leak per unit time, usually in mbar·L/s.

Any window, joint or unit that is letting water in, as tracked on a leak investigation punch list. Shop talk

The shallowest depth over a wreck, rock or other feature, which is the value that gets charted.

Light-Emitting Diode: a semiconductor light source, made white for lighting by coating a blue chip with phosphor.

A thread that tightens counterclockwise, used where normal rotation would loosen a right-hand fastener.

A tool that does not exist, which new apprentices are sent to fetch as a rite of initiation. Shop talk

How far a fillet weld reaches along each member from the corner, the dimension used to call out fillet size.

Theater slang for an ellipsoidal reflector spotlight, the hard-edged fixture with shutters and a gobo slot. Shop talk

Precise measurement of height differences between bench marks and the gauge or staff using a level and rods.

The measured distances between sensors on a survey vessel, used to carry positions and motion to each sonar.

Measure of how far a data point's input values sit from the rest, which gives it outsized pull on a fitted model.

One layer of mix placed and compacted in a single pass of the paver.

One layer of concrete placed in a wall, column or mass pour, or the height cast between horizontal joints.

One layer of fill placed and compacted at a time, the unit by which walls, slopes and embankments are built.

Shop word for coating peeling up at an edge, often after tape removal, grinding or machining. Shop talk

Per-grammage measure of how much light a paper absorbs, written k and given in square meters per kilogram.

A locomotive or set of locomotives running without any cars attached. Shop talk

The transmit and receive optical power readings on a transceiver, read from a meter or the switch's optic diagnostics. Shop talk

A multiplier, usually 0.7 to 0.9, applied to initial light levels to predict what the system delivers after aging and dirt.

The moment a burner ignites, and also the verb for lighting it. Shop talk

To ignite the spray gun, whether striking a plasma arc or lighting an HVOF or flame torch. Shop talk

Per-grammage measure of how strongly a paper redirects light, written s and given in square meters per kilogram.

Unwanted light that crosses a property line or falls where it is not needed, such as into a neighbor's window.

A calibration covering only some ranges or functions of an instrument, flagged with a special sticker. Shop talk

To throw a switch so it routes a train or car onto the intended track. Shop talk

The straight path along which the point of tooth contact travels, tangent to both base circles.

The limit that thermal spray coats only surfaces the gun can point at directly.

The set of pre-planned survey lines, with spacing and orientation, that a vessel follows to achieve the required coverage.

The pair of copper refrigerant lines, one insulated suction line and one smaller liquid line, linking indoor and outdoor units. Shop talk

How fast the conveyor moves, in feet per minute, which sets washer time, spray time and oven time all at once.

Everyday site name for a geomembrane, or for the whole barrier system it belongs to. Shop talk

The spectral width of a single-frequency laser's output, usually given in Hz, kHz or MHz at half maximum.

Loose fibers and fragments a fabric sheds during handling, flexing or use.

Describes a fiber that is carrying live traffic from active equipment, as opposed to dark. Shop talk

A single pane or unit of glass in a window, door or curtain wall opening.

Grease thickener made from a lithium soap plus a complexing acid, the all-purpose bearing workhorse.

Connected to a source of voltage, or describing a conductor meant to be energised in normal use.

A haul trailer with a conveyor floor that unloads mix out the back without raising the bed. Shop talk

Spot in a circulating system where oil is moving and well mixed, the right place to pull a sample. Shop talk

Linear low-density polyethylene: a softer, more flexible geomembrane polymer that follows uneven ground better than HDPE.

The standard method for measuring a complete LED luminaire's light output, power, efficacy, color and distribution.

The test method for tracking how LED packages lose light over time, the basis of lifetime claims.

Large Mode Area: fiber with an enlarged core that spreads light out to raise nonlinear and damage limits.

Linear no-threshold model: the assumption that cancer risk rises in direct proportion to dose, with no safe threshold.

Shop name for low-melt polyester binder fiber, usually a copolyester sheath on a standard PET core. Shop talk

Small chamber that is pumped and vented to pass parts in and out without venting the main process chamber.

Deliberate disconnection of blocks of customer load to stop frequency or voltage from collapsing.

The printed slip that travels with every truck showing mix type, tonnage, time and plant data for that load.

Buildup of fiber and finish residue in card clothing, which clogs the teeth and spoils the web. Shop talk

Loss of coolant accident: a break or leak in the reactor coolant system that lets coolant escape faster than it can be replaced.

A freight train that works the industries along a line, setting out and picking up cars at each customer. Shop talk

The stable locked state of a laser, either mode-locked pulsing or frequency-locked to a reference. Shop talk

A safety shutdown that holds the burner off until someone presses a manual reset.

Thickness and springiness of a nonwoven, especially its ability to recover thickness after being compressed.

Running a road locomotive with its long engine hood leading and the short hood trailing. Shop talk

The seam running lengthwise between two adjacent paving passes, the usual weak spot in an asphalt road.

One of the discrete frequencies at which a standing wave fits a whole number of half-wavelengths into the resonator.

Visual check of formation made by holding a sheet up to a light and judging how even or cloudy it looks. Shop talk

Outside plant cable whose fibers float inside gel-filled or dry tubes, protecting them from strain and temperature changes.

The calculated total loss a fiber link should have, built from fiber length, connectors and splices.

Said when an echo sounder stops tracking the real seabed and reports noise, a second echo or nothing. Shop talk

CP tech shorthand for a potential that is not negative enough to meet the protection criterion. Shop talk

Dense castable with 1 to 2.5 percent lime from cement, using micro-fines and dispersants for strength and low porosity.

Powder formulated to cure at lower oven temperatures, used to save energy or coat heat-sensitive parts.

The rule that a burner must light off at its minimum firing position, proven by a switch, before increasing rate.

Shorthand for the lower low water of the day in places with mixed tides. Shop talk

A safety control that shuts the burner off when the boiler water level drops below a safe point.

Linear polarization resistance: an electrochemical method that reads corrosion rate in minutes in conductive liquids.

Locked rotor amps: the current a motor draws at the instant of starting, before it turns, listed on the nameplate.

Low surface energy, describing plastics and coatings that most adhesives cannot wet or bond without help.

Long-term design strength: reinforcement strength left after reductions for creep, installation damage and aging.

Lot tolerance percent defective: the poor quality level that a sampling plan should reject with high probability.

Cable pulling lubricant applied to fiber cable and duct to cut friction and keep pulling tension down. Shop talk

Scheduled walk through the plant to grease, top off and inspect a set list of lubrication points. Shop talk

Color- or shape-coded label at a fill point that tells techs exactly which lubricant goes in. Shop talk

Lubrication technician, the person who owns the lube routes, oil sampling and lube room in a plant. Shop talk

The unit of total visible light leaving a source, with each wavelength counted by how bright it looks to the eye.

Designer and rep shorthand for the delivered lumen output option of a luminaire, chosen from a catalog range. Shop talk

The whole light fixture as one product: light source, optics, housing, driver or ballast and power connection.

The brightness of a surface or source as seen from a particular direction, measured in candelas per square meter.

Tristimulus Y: the overall lightness of a sample as the eye sees it under a given illuminant and observer.

How many lumens a light source or luminaire produces for each watt of electric power, in lm/W.

The total amount of visible light a source emits in all directions, weighted for the eye's sensitivity and measured in lumens.

How much light a source sends out in one specific direction, measured in candelas.

The time for the Moon to return to the same meridian, about 24 hours 50 minutes, which sets the daily tide rhythm.

How long a place waits after the Moon crosses its meridian before the next high or low water arrives.

A flat-bladed rake used by paving crews to move, level and smooth hot mix by hand.

The metric measure of light landing on a surface: one lumen falling evenly on each square meter.