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A measure having as its zero point or base the complete absence of the entity being measured.

Absolute pressure:
The pressure above zero absolute, i.e., the sum of atmospheric and gauge pressure.  In vacuum related work it is usually expressed in millimeters, or inches, of mercury.

Acceptance sampling:
A statistical quality control method that seeks to determine the quality of a product by sampling a small portion of it.  It does not assure that 100 percent of the product is acceptable, but reduces the likelihood of acceptance of a defective product.

A container in which fluid (generally nitrogen) is stored under pressure as a source of fluid power.

Acre (a):
A unit of area used in English-speaking countries, equal to 4,840 square yards (0.405 hectares).

A device for converting pneumatic or hydraulic energy into mechanical energy.  A motor or cylinder.

A substance capable of holding materials together by surface attachment. It is a general term and includes cements, mucilage, and paste, as well as glue.

Agricultural Residue:
Plant parts, primarily stalks and leaves, not removed from the fields with the primary food or fiber product. Examples include corn stover (stalks, leaves, husks, and cobs); wheat straw; and rice straw.

A device for amplifying the error signal sufficiently to cause actuation of the stroke control.  Several types of servo amplifiers are used at the present time: electronic (DC, AC, phase sensitive, and magnetic) and mechanical.

Amplitude of sound:
The loudness of a sound.

Anaerobic digestion:
Decomposition of biological wastes by micro-organisms, usually under wet conditions, in the absence of air (oxygen), to produce a gas comprising mostly methane and carbon dioxide.

A continuous range of numbers or values.

Exhibiting different properties when measured along different axes.  In general, fibrous materials such as wood are anisotropic.

Annular area:
A ring shaped area - often refers to the net effective area of the rod side of a cylinder piston, i.e., the piston area minus the cross-sectional area of the rod.

Aquatic Plants:
The wide variety of aquatic biomass resources, such as algae, giant kelp, other seaweed, and water hyacinth. Certain microalgae can produce hydrogen and oxygen while others manufacture hydrocarbons and a host of other products. Microalgae examples include Chlorella, Dunaliella, and Euglena.

Atmospheric pressure:
Pressure exerted by the atmosphere at any specific location.  (Sea level pressure is approximately 14.7 pounds per square inch absolute.)

Axial force:
A push (compression) or pull (tension) acting along the length of a member, expressed in kilonewtons (pounds).

Axial stress:
The axial force acting at a point along the length of a member divided by the cross-sectional area of a member, expressed in kilopascals (pounds per square inch).

A mixture of 20% biodiesel and 80% petroleum diesel based on volume.

Back connected:
A condition where pipe connections are on normally unexposed surfaces of hydraulic equipment.  (Gasket mounted units are back connected.)

Back pressure:
A pressure in series.  Usually refers to pressure existing on the discharge side of a load.  It adds to the pressure required to move the load.

A small single-cell organism. Bacteria do not have an organized nucleus, but they do have a cell membrane and protective cell wall. Bacteria can be used to ferment sugars to ethanol.

An air pollution control device that captures particulate in filter bags.

Barrel of oil equivalent (boe):
The amount of energy contained in a barrel of crude oil, i.e. approximately 6.1 GJ (5.8 million Btu), equivalent to 1,700 kWh. A "petroleum barrel" is a liquid measure equal to 42 U.S. gallons (35 Imperial gallons or 159 liters); about 7.2 barrels are equivalent to one tonne of oil (metric).

A part on which the arbor, pivot, pin, or the like, turns or revolves.

Part of the conveyor on which pieces of wood are displaced.

A work area made hazardous by a line or equipment under tension.

Biochemical conversion:
The use of fermentation or anaerobic digestion to produce fuels and chemicals from organic sources.

Something that breaks down to its component parts in the environment.

Useful, renewable energy produced from organic matter. The conversion of the complex carbohydrates in organic matter to energy. Organic matter may either be used directly as a fuel or processed into liquids and gases.

A combustible gas derived from decomposing biological waste under anaerobic conditions.

The quantity of biological matter of one or more species present on a unit area.  With respect to trees, biomass can be expressed in terms of various components (wood, bark, foliage, roots, etc.) of all trees on a unit area or of a single tree; biomass quantities of trees are commonly expressed on an oven-dry weight basis.

Biomass boiler:
Biomass boilers burn bark, sander dust and other wood-related scrap not usable in product production. Also called "hogged fuel" boilers, biomass boilers make steam and heat for mill use.

Biomass fuel:
Liquid, solid, or gaseous fuel produced by conversion of biomass. Examples include bioethanol from sugar cane or corn, charcoal or woodchips, and biogas from anaerobic decomposition of wastes.

Biomass Processing Residues:
Byproducts from processing all forms of biomass that have significant energy potential. Because these residues are already collected at the point of processing, they can be convenient and relatively inexpensive sources of biomass for energy.

The smallest unit of memory in a computer.  A bit is a single digit and can only have the values 0 or 1.  Bits are combined into words of memory.

To divert a specific controllable portion of hydraulic pump delivery directly to reservoir.

Steam generation equipment.

Bond strength:
The unit load applied in tension, compression, flexure, cleavage, or shear, required to break an adhesive assembly, with failure occurring in or near the plane of the bond.

Bone-dry ton (BDT):
Material that weighs 2,000 pounds at zero percent moisture content. Also known as an Ovendry ton or Bone Dry Metric Ton.

Bone-dry unit (BDU):
A quantity of wood residue that would weigh 2,400 pounds at zero percent moisture content.

Bottoming cycle:
A cogeneration system in which steam is used first for process heat and then for electric power production.

As in welding, a method of adhering or soldering carbide or other hard metal teeth inserts, or joining pieces of metal.

A device which permits air to move in and out of a container or component to maintain atmospheric pressure.

British thermal unit (Btu):
The quantity of heat required to raise the temperature of one pound of water by one degree Fahrenheit.

1.  Adjusting the control or recording equipment to reflect the actual control or recording
2.  Procedures that involve scanning an object of known size.  Calibration is used to adjust
     scanner readings for greater accuracy.

Calorific value:
The potential heat-production value of a wood source.  Depends on the cellulose-lignin ratio, the percentage of extractives, and the moisture content.

Can velocity:
The velocity of the gas in the passages between the filter units in the filter house of a gas filter.

Capillary action:
The combination of solid-liquid adhesion and surface tension by which liquid moves through a cellular structure.

Capital cost:
The total investment needed to complete a project and bring it to a commercially operable status. The cost of construction of a new plant or the expenditures for the purchase/acquisition of existing facilities.

Carbon dioxide (CO2):
A colorless, odorless gas produced by respiration and combustion of carbon-containing fuels. Plants use it as a food in the photosynthesis process.

Carbon monoxide (CO):
A colorless, odorless, poisonous gas produced by incomplete combustion.

1.  The replaceable element of a fluid filter.
2.  The pumping unit from a vane pump, composed of the rotor, ring, vanes and one or both side

A substance that increases the rate of a chemical reaction, without being consumed or produced by the reaction. Enzymes are catalysts for many biochemical reactions.

A localized gaseous condition within a liquid stream which occurs where the pressure is reduced to the vapor pressure.

A family of enzymes that break down cellulose into glucose molecules.

One of the major structural materials in the plant cell walls that can be utilized by microorganisms in the rumen.

Celsius (C):
The international temperature scale in which water freezes at 0 and boils at 100 under normal atmospheric conditions.   °C = (°F - 32) ÷ 1.8.

Centimetre (cm):
A metric unit of length equal to one hundredth of a metre.  2.54 cm is equal to one inch.

Centrifugal force:
The force which impels a thing, or parts of a thing, outward from a center of rotation.

A fluid passage, the length of which is large with respect to its cross-sectional dimension.

The remains of solid biomass that has been incompletely combusted, such as charcoal if wood is incompletely burned.

Charge pressure:
The pressure at which replenishing fluid is forced into the hydraulic system (above atmospheric pressure).

Charge (supercharge):
1.  To replenish a hydraulic system above atmospheric pressure.
2.  To fill an accumulator with fluid under pressure. (See Precharge pressure)

Check valve:
A valve which permits flow of fluid in one direction only.

Device used to transform pieces of wood to chips by knife action.

Thin, short pieces of wood used as a raw material for biomass fuel, pulping and fiberboard production. The product of chippers. Chips are larger and coarser than sawdust.

An arrangement of components interconnected to perform a specific function within a system.

Closed center valve:
One in which all ports are blocked in the center or neutral position.

Closed loop:
A system in which the output of one or more elements is compared to some other signal to provide an actuating signal to control the output of the loop.

The process of burning fuel to produce electricity and usable steam.

Co-gen operation:
Refers to the production of usable steam and electricity using a particular kind of fuel (for example, woodchips, oil, coal, hydro).

A free standing axially loaded compression member, usually vertical.

Combined cycle:
Two or more generation processes in series or in parallel, configured to optimize the energy output of the system.

Combustion air:
The air fed to a fire to provide oxygen for combustion of fuel. It may be preheated before injection into a furnace.

Combustion (Burning):
The transformation of biomass fuel into heat, chemicals, and gases through chemical combination of hydrogen and carbon in the fuel with oxygen in the air.

Combustion efficiency:
(actual heat produced by combustion) divided by (total heat potential of the fuel consumed)

Command signal (or input signal):
An external signal to which the servo must respond.

Compensator control:
A displacement control for variable pumps and motors which alters displacement in response to pressure changes in the system as related to its adjusted pressure setting.

Built-up, bonded products consisting wholly of natural wood, or in combination with metals, plastics, etc.

The change in volume of a unit volume of a fluid when it is subjected to a unit change in pressure.

Computer simulations:
Computer software that models actions or occurrences in the real world.

A device used to regulate the function of a unit (See Hydraulic control, Manual control, Mechanical control, and Compensator control).

Control console:
Fabricated metal cabinet housing buttons and switches for the control of a machine center.

Control valve:
A device that controls the flow of liquids or gases.

A stack of wood consisting of 128 cubic feet (3.62 cubic meters). A cord has standard dimensions of 4 x 4 x 8 feet, including air space and bark.

Counterbalance valve:
A pressure control valve which maintains back pressure to prevent a load from falling.

Cracking pressure:
The pressure at which a pressure actuated valve begins to pass fluid.

To change the properties of an adhesive by chemical reaction (which may be condensation, polymerization, or vulcanization) and thereby develop maximum strength.  Usually accomplished by the action of heat or a catalyst with or without pressure.

A device sometimes built into the ends of a hydraulic or pneumatic cylinder which restricts the flow of fluid at the outlet port, thereby arresting the motion of the piston rod.

A device which converts fluid power or air into linear mechanical force and motion.  It usually consists of a movable element such as a piston and piston rod, plunger rod, plunger or ram, operating within a cylindrical bore.

The region or band of no response where an error signal will not cause a corresponding actuation of the controlled variable.

The slow release of confined fluid to gradually reduce pressure on the fluid.

The amount of change in a number, size or position.

When applied to feed rations, describes the amount of nutrients within a measurement unit of the total ration.

A device for removing the excess heat in steam as its pressure is reduced.

To close the vent connection of a pressure control valve permitting the valve to function at its adjusted pressure setting.

Differential current:
The algebraic summation of the current in the torque motor; measured in MA (milliamperes).

Differential cylinder:
Any cylinder in which the two opposed piston areas are not equal.

Movement of moisture from areas of high to low concentration or temperature.

An airtight vessel or enclosure in which bacteria decomposes biomass in water to produce biogas.

Directional valve:
A valve which selectively directs or prevents fluid flow to desired channels.

The quantity of fluid which can pass through a pump, motor or cylinder in a single revolution or stroke.

A low amplitude, relatively high frequency periodic electrical signal, sometimes superimposed on the servo valve input to improve system resolution.  Dither is expressed by the dither frequency (Hz) and the peak-to-peak dither current amplitude (ma).

Double sheave:
A pulley block with two grooved wheels.

Downdraft gasifier:
A gasifier in which the product gases pass through a combustion zone at the bottom of the gasifier.

A passage in, or a line from, a hydraulic component which returns leakage fluid independently to reservoir or to a vented manifold.

Drive pulley:
The first of a train of wheels, giving motion to the rest.

A mixture of 10% ethanol and 90% gasoline based on volume.

A mixture of 85% ethanol and 15% gasoline based on volume.

The ratio of output to input.  Volumetric efficiency of a pump is the actual output in gpm divided by the theoretical or design output.  The overall efficiency of a hydraulic system is the output power divided by the input power.  Efficiency is usually expressed as a percent.

The liquid or gas discharged from a process or chemical reactor, usually containing residues from that process.

Electro-hydraulic servo valve:
A directional type valve which receives a variable or controlled electrical signal and which controls or meters hydraulic flow.

Device attached to a moving chain that produces an electrical signal each time the chain moves a fixed distance.  The encoder is attached to the chain and used to track the movement of the pieces through a scanner.

The ability or capacity to do work.  Measured in units of work.

Energy crops (Bioenergy crops):
Are fast-growing crops that are grown for the specific purpose of producing energy (electricity, thermal energy, solid or liquid fuels) from all or part of the resulting plant.


The aggregate of physical, chemical and biological factors that act upon an organism or an ecological community and ultimately determine its form and survival.

A protein or protein-based molecule that speeds up chemical reactions occurring in living things. Enzymes act as catalysts for a single reaction, converting a specific set of reactants into specific products.

Error (signal):
The signal which is the albraic summation of an input signal and a feedback signal.

A colorless, flammable liquid produced by fermentation of sugars. Ethanol is used as a fuel oxygenate. Ethanol is the alcohol found in alcoholic beverages.

Changing water from a liquid to a vapor form.

Excess air:
Refers to the quantity of air supplied that exceeds the minimum necessary to support the combustion chemistry.

A cost or benefit not accounted for in the price of goods or services. Often refers to the cost of pollution and other environmental impacts.

Fahrenheit (F):
The temperature scale in which water freezes at 32 degrees F and boils at 212 degrees F under normal atmospheric conditions.  F = (C x 1.8) + 32.

Fan pitch:
The angle of the fan blades measured one-third of the fan radius in from the tip.

Fans, variable-speed:
Fans whose motors turn at infinitely variable speeds by varying the line frequency of the power source.

Feedback loop:
Any closed circuit consisting of one or more forward elements and one or more feedback elements.

Feedback (or feedback signal):
The output signal from a feedback element.

Feed speed:
The speed of a machine centre (canter, planer, etc.) usually expressed in feet per minute.

A material used as a raw material in an industrial process.

Conversion of carbon-containing compounds by micro-organisms for production of fuels and chemicals such as alcohols, acids or energy-rich gases.

A device whose primary function is the retention by a porous media of insoluble contaminants from a fluid.

Firm power (Firm energy):
Power which is guaranteed by the supplier to be available at all times during a period covered by a commitment.

Flow control valve:
A valve which controls the rate of oil flow.

Flow rate:
The volume, mass, or weight of a fluid passing through any conductor per unit of time.

1.  A liquid or gas.
2.  A liquid that is specially compounded for use as a power-transmitting medium in a hydraulic

Fluidized-bed boiler:
Vessel where a fluidized bed is formed by blowing air up through a layer of inert particles (such as sand or limestone) at a rate that causes the particles to go into suspension and continuous motion. The super-hot bed material increases combustion efficiency by its direct contact with the fuel.

Follow valve:
A control valve which ports oil to an actuator so the resulting output motion is proportional to the input motion to the valve.

Foot (ft):
A linear unit of length equal to 12 inches or a third of a yard (0.3048 m).

Falling object protective structure.

Any push or pull measured in units of weight.  In hydraulics, total force is expressed by the product P (force per unit area) and the area of the surface on which the pressure acts.  F = P x A.

Forest residues:
Material not harvested or removed from logging sites in commercial hardwood and softwood stands as well as material resulting from forest management operations such as precommercial thinnings and removal of dead and dying trees.

Four-way valve:
A directional valve having four flow paths.

Feet per minute.

1.  The number of cycles per second of alternating current (example: 60 cycles per second or 60
     hertz per second).
2.  The number of times an action occurs in a unit of time.  Frequency is the basis of all sound. 
     A pump or motor's basic frequency is equal to its speed in revolutions per second multiplied
     by the number of pumping chambers.

Front connected:
A condition wherein piping connections are on normally exposed surfaces of hydraulic components.

Front end loader:
A mobile machine mounted on a wheeled or tracked chassis, equipped with a grapple, tuck, bucket, or fork-lift device, and employed in the loading, unloading, stacking, or sorting of logs or materials.

Fuel cycle:
The series of steps required to produce electricity. The fuel cycle includes acquiring the raw fuel source, processing and cleaning the fuel, transport, electricity generation, waste management and plant decommissioning.

Full flow:
In a filter, the condition where all the fluid must pass through the filter element or medium.

An enclosed chamber or container used to burn biomass in a controlled manner to produce heat for space or process heating.

Gallon (gal):
A unit of volume.  A US gallon is equal to 4 quarts or 231 cubic inches (approximately 3.79 liters).  A British imperial gallon is equal to four quarts or 4.55 liters.

A chemical or heat process to convert a solid fuel to a gaseous form.

A device for converting solid fuel into gaseous fuel. In biomass systems, the process is referred to as pyrolitic distillation.

Gauge pressure:
A pressure scale which ignores atmospheric pressure.  Its zero point is 14.7 psi absolute.

Gigawatt (GW):
A measure of electrical power equal to one billion watts (1,000,000 kW).

Originally, a hard gelatin obtained from hides, tendons, cartilage, bones, etc., of animals.  Also, an adhesive prepared from this substance by heating with water.  Through general use the term is now synonymous with the term "Adhesive".

A liquid by-product of biodiesel production. Glycerin is used in the manufacture of dynamite, cosmetics, liquid soaps, inks, and lubricants.

Gram (g):
A metric unit of weight equal to one thousandth of a kilogram; one ounce is approximately 28 grams.

Greenhouse effect:
The effect of certain gases in the Earth's atmosphere in trapping heat from the sun.

Greenhouse gases:
Gases that provide an insulating effect in the earth's atmosphere, potentially leading to global climate change. These gases include carbon dioxide, methane, nitrous oxide, ozone, and water vapour.

The height of a column or body of fluid above a given point expressed in linear units.  Head is often used to indicate gage pressure.  Pressure  is equal to the height times the density of the fluid.

The form of energy that has the capacity to create warmth or to increase the temperature of a substance. Any energy that is wasted or used to overcome friction is converted to heat.  Heat is measured in calories or British thermal units (Btu's).  One Btu is the amount of heat required to raise the temperature of one pound of water one degree Fahrenheit.

Heat exchanger:
A device which transfers heat through a conducting wall from one fluid to another.

Heating value:
The maximum amount of energy that is available from burning a substance.

Heat rate:
The amount of fuel energy required by a power plant to produce one kilowatt-hour of electrical output.

Hectare (ha):
A metric unit of area, 100 metres by 100 metres (10,000 square metres); equivalent to 2.471 acres.

Spiral-shaped: in the shape of a helix or spiral.

The polysaccharide fraction existing in the cell wall of the plant.  It is similar to cellulose but is only partially digestible in the rumen.

Non-woody type of vegetation, usually lacking permanent strong stems, such as grasses, cereals and canola (rape).

Herbaceous Energy Crops:
Perennial non-woody crops that are harvested annually, though they may take 2 to 3 years to reach full productivity. Examples include: Switchgrass, Reed canarygrass, Miscanthus, and Giant reed.

Hertz (Hz):
Unit of frequency; equal to one cycle per second (cps).

Higher heating value (HHV):
The maximum potential energy in dry fuel. For wood, the range is from 7,600 to 9,600 Btu/lb (17.7 to 22.3 GJ/t).

Hog fuel:
Waste wood that is used for generation of heat and process energy; made by reducing bark to a usable size.

The total carbohydrate fraction of a plant. That is, cellulose plus hemicellulose.

Horsepower (hp):
The power required to lift 550 pounds one foot in one second or 33,000 pounds one foot in one minute.  A horsepower is equal to 746 watts or to 42.2 British thermal units per minute.

To move or convey by fluid.

Hydraulic balance:
A condition of equal opposed hydraulic forces acting on a part in a hydraulic component.

Hydraulic control:
A control which is actuated by hydraulically induced forces.

Engineering science pertaining to liquid pressure and flow.

Engineering science pertaining to the energy of liquid flow and pressure.

A chemical reaction that releases sugars, which are normally linked together in complex chains. In ethanol production, hydrolysis reactions are used to break down the cellulose and hemicellulose in the biomass.

Engineering science pertaining to the energy of liquids at rest.

An instrument for measuring the humidity of air.

Changes its moisture content to be in equilibrium with the atmosphere.

Inch (in):
A unit of length equal to one-twelfth of a foot (2.54 cm).

Inclined grate:
A type of furnace in which fuel enters at the top part of a grate in a continuous ribbon, passes over the upper drying section where moisture is removed, and descends into the lower burning section. Ash is removed at the lower part of the grate.

Indirect liquefaction:
Conversion of biomass to a liquid fuel through a synthesis gas intermediate step.

Exhibiting the same properties in all directions.

Joule (J):
1.  A unit of energy equal to the work done when a force of one newton acts through a distance
     of one metre.  One joule is equivalent to one watt second or 0.737 foot pounds.
2.  A unit of electrical energy equal to the work done when a current of one ampere is passed
     through a resistance of one ohm for one second.

Stick or handle type input device mounted on the operator's console.  Some joysticks have buttons mounted on the handle.  Moving the joystick handle can send either discrete or analog input signals to the PLC.

Kappa number:
A test for the degree of lignification of pulps.

A small, parallel-sided piece, flat or tapered on top, for securing pulleys and other parts to shafts.

A groove or channel for a key, as in a shaft or the hub of a pulley; a keyseat.

Kilogram (kg):
The basic unit of mass in the SI system, equal to 1,000 grams (approximately 2.2 lbs).

Kilometre (km):
A measure of length equal to 1,000 metres or 0.62 miles.

Kilowatt hour (kWh):
A measure of energy equivalent to the expenditure of one kilowatt for one hour. For example, 1 kWh will light a 100-watt light bulb for 10 hours. 1 kWh = 3,413 Btu.

Kilowatt (kW):
A measure of electrical power equal to 1,000 watts. 1 kW = 3,413 Btu/hr = 1.341 horsepower.

Kinetic energy:
Energy that a substance or body has by virtue of its mass (weight) and velocity.

A hydraulically operated loading boom whose mechanical action imitates the human arm. Common on "forwarders".

Laminar (flow):
A condition where the fluid particles move in continuous parallel paths.

A product made by bonding together two or more layers (laminations) of material or materials.

Landfill gas:
A type of biogas that is generated by decomposition of organic material at landfill disposal sites.

Perfectly horizontal.

Levelized life-cycle cost:
The present value of the cost of a resource, including capital, financing and operating costs, expressed as a stream of equal annual payments. By levelizing costs, resources with different lifetimes and generating capabilities can be compared.

A gain in output force over input force by sacrificing the distance moved.  Mechanical advantage or force multiplication.

The height a body or column of fluid is raised; for instance, from the reservoir to the pump inlet.  Lift is sometimes used to express a negative pressure or vacuum.  The opposite of head.

A complex indigestible substance that is a major structural component of mature plants.  It is contained in the fibrous portion of stems, leaves, cobs and hulls of plants.

Limit switch:
Electrical device that transmits an electrical signal when in physical contact with an object.

A tube, pipe or hose which acts as a conductor of hydraulic fluid.

Linear actuator:
A device for converting hydraulic energy into linear motion - a cylinder or ram. 

Liter (l):
Basic unit of volume in the metric system equal to 1,000 cubic centimetres (1.056 US quarts).

Any of a variety of machines, wheel or track mounted, designed primarily to lift and load a truck, train or other mode of transportation.

A fluid conductor which provides multiple connection ports.

Manual control:
A control actuated by the operator, regardless of the means of actuation.  Example: Lever or foot pedal control for directional valves.

Manual override:
A means of manually actuating an automatically-controlled device.

Marine borers:
Mollusks and crustaceans which attack submerged wood in salt and brackish water.

Material balance:
A relationship, often portrayed in a diagram, that shows how all components of a raw material are allocated and used.

Mechanical control:
Any control actuated by linkages, gears, screws, cams or other mechanical elements.

Megawatt (MW):
A measure of electrical power equal to one million watts (1,000 kW).

To regulate the amount or rate of fluid flow.

To regulate the amount of fluid flow into an actuator or system.

To regulate the flow of the discharge fluid from an actuator or system.

Metre (m):
The metric basic unit for linear measurement equal to 39.37 inches (1.094 yards).

One-millionth of a metre or approximately .00004 inch.

Micron rating:
The size of the particles a filter will remove.

Mile (mi):
A unit of linear measurement on land, equivalent to 5,280 feet (1,760 yd) or 1.6 kilometres.

Millimetre (mm):
A unit of length equal to one thousandth of a metre (0.0394 inches).

A common method of pricing electricity in the U.S. Tenths of a U.S. cent per kilowatt hour.

Mill residue:
Wood and bark residues produced in processing logs into lumber, plywood, and paper.

One million British thermal units.

To control within an infinite range between 0 percent and 100 percent as opposed to on/off control.

Screen on which an electronics systems display information.

A device which converts electricity or hydraulic fluid power into mechanical force and motion.  It usually provides rotary mechanical motion.

Motor control center (MCC):
Central location for circuit breakers for mill equipment.

Municipal Wastes:
Residential, commercial, and institutional post-consumer wastes contain a significant proportion of plant-derived organic material that constitutes a renewable energy resource. Waste paper, cardboard, construction and demolition wood waste, and yard wastes are examples of biomass resources in municipal wastes.

Net present value:
The sum of the costs and benefits of a project or activity. Future benefits and costs are discounted to account for interest costs.

Newton (N):
Unit of force equivalent to the force that produces an acceleration of one metre per second per second on a mass of one kilogram.

Nitrogen fixation:
The transformation of atmospheric nitrogen into nitrogen compounds that can be used by growing plants.

Open center circuit:
One in which pump delivery flows freely through the system and back to the reservoir in neutral.

Open center valve:
One in which all ports are interconnected and open to each other in the center or neutral position.

A restriction, the length of which is small in respect to its cross-sectional dimensions.

An oxygenate is a compound which contains oxygen in its molecular structure. Ethanol and biodiesel act as oxygenates when they are blended with conventional fuels. Oxygenated fuel improves combustion efficiency and reduces tailpipe emissions of CO.

Pascal (Pa):
A unit of pressure or stress equal to one newton per square metre.

Device used to detect the presence of an object.  A photocell is composed of a transmitter, which transmits an infrared signal to a receiver or reflector.

A process that plants use to synthesize nutrients from water and minerals using sunlight.

A long, heavy timber, round or square, driven deep into the ground to provide a secure foundation for structures built on soft, wet, or submerged sites (e.g., landing stages, bridge abutments).

Pilot pressure:
Auxiliary pressure used to actuate or control hydraulic components.

Pilot scale:
The size of a system between the small laboratory model size (bench scale) and a full-size system.

Pilot valve:
An auxiliary valve used to control the operation of another valve.  The controlling stage of a 2-stage valve.

A cylindrically shaped part which fits within a cylinder and transmits or receives motion by means of a connecting rod.

Programmable logic controllers.  Industrial computer with I/O capability, which programs in ladder-relay logic.

Straight up and down, perfectly vertical.

A cylindrically shaped part which has only one diameter and is used to transmit thrust.  A ram.

That part of certain valves which prevents flow when it closes against a seat.

An internal or external terminus of a passage in a component.

Positive displacement:
A characteristic of a pump or motor which has the inlet positively sealed from the outlet so that fluid cannot recirculate in the component.

A control element in the servo system which measures and controls electrical potential.

Pound (lb):
A unit of weight equal to 16 ounces (0.45 kilograms).

Work per unit of time.  Measured in horsepower (hp) or watts (W).

Power boiler:
A boiler that uses wood waste and natural gas as fuel to produce process steam.

Power pack:
An integral power supply unit usually containing a pump, reservoir, relief valve and directional control.

Precharge pressure:
The pressure of compressed gas in an accumulator prior to the admission of liquid.

Present value:
The worth of future receipts or costs expressed in current value. To obtain present value, an interest rate is used to discount future receipts or costs.

Force per unit area. Usually measured in pounds per square inch (PSI) or kilopascals (kPa). A kilopascal is equal to 1000 newtons per square metre or 0.0102 kg/sq cm (0.145 lb/sq in).

Pressure drop:
The difference in pressure between any two points of a system or a component.

Pressure line:
The line carrying the fluid from the pump outlet to the pressurized port of the actuator.

Pressure override:
The difference between the cracking pressure of a valve and the pressure reached when the valve is passing full flow.

Pressure plate:
A side plate in a vane pump or motor cartridge on the pressure port side.

Pressure reducing valve:
A valve which limits the maximum pressure at its outlet regardless of the inlet pressure.

Pressure switch:
1.  An electric switch operated by fluid pressure.
2.  Switches that read the available pressure in air and hydraulic lines.  These switches are
     often used as a safety feature, to prevent equipment from operating when there is not enough
     air pressure or hydraulic fluid pressure.

Process heat:
Heat used in an industrial process rather than for space heating or other housekeeping purposes.

Producer gas:
Fuel gas high in carbon monoxide (CO) and hydrogen (H2), produced by burning a solid fuel with insufficient air or by passing a mixture of air and steam through a burning bed of solid fuel.

Proportional flow:
In a filter, the condition where part of the flow passes through the filter element in proportion to pressure drop.

Proximity switch:
Photoelectric switches that are triggered as a piece passes near them.  Proximity switches are used to detect the presence or absence of material.

Pounds per square inch.

A device which converts mechanical force and motion into hydraulic fluid power.

The thermal decomposition of biomass at high temperatures in the absence of air. The end product of pyrolysis is a mixture of solids (char), liquids (oxygenated oils), and gases (methane, carbon monoxide, and carbon dioxide).

One quadrillion Btu (10^15 Btu) = 1.055 exajoules (EJ), or approximately 172 million barrels of oil equivalent.

Quality control:
Any activity that helps to maximize the value of the raw material through all phases of the manufacturing process.

A single-acting cylinder with a single diameter plunger rather than a piston and rod.  The plunger in a ram-type cylinder.

Head of a scanner that monitors the infrared signals transmitted by the transmitter head.

Back-and-forth straight line motion or oscillation.

Recoverable heat:
Heat energy from combustion that is actually recovered to do useful work.

1.  Product recovery: An expression of the amount of product (nominal or actual) that can be
     manufactured from a given input of raw material.
2.  Logging recovery: The volume or weight of logs that can be harvested from a given volume of
     standing timber.

Recovery boiler:
A boiler that recovers process chemicals for re-use and creates process steam with the heat it generates.

Refractory lining:
A lining, usually of ceramic, capable of resisting and maintaining high temperatures.

Regenerative circuit:
A piping arrangement for a differential type cylinder in which discharge fluid from the rod end combines with pump delivery to be directed into the head end.

Relative humidity:
Ratio of the amount of water vapour present in the air to that which the air would hold at saturation at the same temperature.  It is usually considered on the basis of the weight of the vapour but, for accuracy, should be considered on the basis of vapour pressures.

Relief valve:
A pressure operated valve which by-passes pump delivery to the reservoir, limiting system pressure to a predetermined maximum value.

To add fluid to maintain a full hydraulic system.

Reserve margin:
The amount by which the utility's total electric power capacity exceeds maximum electric demand.

Residues (Biomass):
Byproducts from processing all forms of biomass that have significant energy potential. Because these residues are already collected at the point of processing, they can be convenient and relatively inexpensive sources of biomass for energy.

An ingredient of coatings which acts as a binder and gives the coating physical properties such as hardness and durability.

The smallest unit used for taking measurements from a scanner or the encoder.

A reduced cross-sectional area in a line or passage which produces a pressure drop.

Return line:
A line used to carry exhaust fluid from the actuator back to sump.

Return on investment (ROI):
The interest rate at which the net present value of a project is zero. Multiple values are possible.

Reversing valve:
A four-way directional valve used to reverse a double-acting cylinder or reversible motor.

A cylindrical body movable about its longitudinal axis.

Rotary actuator:
A device for converting hydraulic energy into rotary motion - a hydraulic motor.

Revolutions per minute.

A temperature measuring device that measures the change in electrical resistance to determine temperature (resistive thermal device).

An element of the PLC ladder logic program.  Each rung looks at input signals and turns output signals on or off.  The program runs by scanning the ladder logic, testing the input points and the instructions on each rung, and turning the output points on or off.

Saturated steam:
Steam at boiling temperature for a given pressure.

Generally an optical or laser/camera measuring device.  Scanners are composed of a transmitter head and a receiver head, which permit electronics system to obtain the shape and the dimensions an object.

The order of a series of operations or movements.

Sequencing valve:
A pressure operated valve which, at its setting, diverts flow to a secondary line while holding a predetermined minimum pressure in the primary line.

Servo mechanism (servo):
A mechanism subjected to the action of a controlling device which will operate as if it were directly actuated by the controlling device, but capable of supplying power output many times that of the controlling device, this power being derived from an external and independent source.

Servo valve:
Electro-mechanical device used to control a setworks hydraulic cylinder.  An electrical signal is sent to the servo valve which opens, allowing hydraulic fluid to flow into the cylinder.  The voltage level and direction of the electrical signal determine the speed and direction of the setworks movement.

Set complete:
The actual position of a setworks is within a certain distance of the command position to which it was sent.

Set complete range:
The maximum distance allowed between the actual position of a setworks and the position to which the setworks was sent.  When the setworks position is in this range, the setworks is at set complete.

Specific gravity.  Also called relative density.  As applied to wood, the ratio of the oven-dry weight of a sample to the weight of a volume of water equal to the volume of the sample at a specified moisture content (green, air-dry, or oven-dry).

Shaft horsepower:
A measure of the actual mechanical energy per unit time delivered to a turning shaft.

The grooved wheel of a pulley.

Pulleys mounted on the end of the drive and motor shaft over which belts pass to transfer rotational force from the motor to the shaft.

A thin piece or strip of metal used to fill in, as in leveling.

Short rotation intensive culture (SRIC):
The growing of tree crops for bioenergy or fiber, characterized by detailed site preparation, usually less than 10 years between harvests, usually fast-growing hybrid trees and intensive management.

Short ton:
2,000 pounds or 0.9072 tonnes.

A control impulse from a control device or sensor.

Snatch block:
A block that can be opened on one side to allow a cable or rope to be laid in the block, instead of threading it through from one end.

Specific gravity:
Also called relative density.  As applied to wood, the ratio of the oven-dry weight of a sample to the weight of a volume of water equal to the volume of the sample at a specified moisture content (green, air-dry, or oven-dry).

A term loosely applied to almost any moving cylindrically shaped part of a hydraulic component which moves to direct flow through the component.

Stack heat loss:
Loss of combustion heat via gas emissions in the smokestack of chimney.

Vapor produced by heating water.

Steam sprays:
Mechanical equipment for introducing water vapor or steam to the kiln environment.

Steam turbine:
A device for converting energy of high-pressure steam (produced in a boiler) into mechanical power which can then be used to generate electricity.

A coarse filter.

Streamline flow:
A condition where the fluid particles move in continuous parallel paths.

1.  The length of travel of a piston or plunger.
2.  To change the displacement of a variable displacement pump or motor.

An auxiliary mounting for a hydraulic component providing a means of connecting piping to the component.

Suction line:
The hydraulic line connecting the pump inlet port to the reservoir or sump.

A reservoir.

1.  To replenish a hydraulic system above atmospheric pressure.
2.  To fill an accumulator with fluid under pressure (See Precharge pressure).

Superheated steam:
Steam which is hotter than boiling temperature for a given pressure.

A transient rise of pressure or flow.

Surplus electricity:
Electricity produced by cogeneration equipment in excess of the needs of an associated factory or business.

Swash plate:
A stationary canted plate in an axial type piston pump which causes the pistons to reciprocate as the cylinder barrel rotates.

A rotary electromagnetic device generally used as an AC feedback signal generator which indicates position.  It can also be used as a reference signal generator.

Tachometer (AC) (DC):
A device which generates an AC or DC signal proportional to the speed at which it is rotated and the polarity of which is dependent on the direction of rotation of the rotor.

A tangential section is a longitudinal section through a tree perpendicular to a radius.  Flat-grain lumber is sawn tangentially.

The reservoir or sump.

Linear displacement transducer.

A unit of energy equal to 100,000 Btus (= 105.5 MJ); used primarily for natural gas.

Thermal oil:
A heat transfer fluid used instead of steam.  They are not interchangeable within the same kiln.  Thermal oil is capable of higher temperatures at low operating pressure and is not susceptible to freezing.

Thermochemical conversion:
Use of heat to chemically change substances from one state to another, e.g. to make useful energy products.

Thermocouple (TC):
A sensor that measures temperature based on the voltage difference between  two dissimilar metals.

Thermosetting glues and resins:
Glues and resins that are cured with heat but do not soften when subsequently subjected to high temperatures.

A unit of weight in the metric system equal to 1,000 kilograms or approximately 2,204 pounds.  Also called a Metric ton.

Ton (T):
1. US unit of weight equal to 2,000 lb; also called a Short ton.
2. British unit of weight equal to 2,240 lb (1,016 kg); also called a Long ton.

Topping and back pressure turbines:
Turbines which operate at exhaust pressure considerably higher than atmospheric (noncondensing turbines). These turbines are often multistage types with relatively high efficiency.

Topping cycle:
A cogeneration system in which electric power is produced first. The reject heat from power production is then used to produce useful process heat.

A rotary thrust.  The turning effort of a fluid motor usually expressed in inch pounds.

Torque converter:
A rotary fluid coupling that is capable of multiplying torque.

Torque motor:
A type of electromechanical transducer having rotary motion used in the input stages of servo valves.

Transducer (or feedback transducer):
An element which measures the results at the load and sends a signal back to the amplifier.

A chemical process which reacts an alcohol with the triglycerides contained in vegetable oils and animal fats to produce biodiesel and glycerin.

A device that separates condensate and air from the steam within the steam heating coils.

Traps, float and thermostatic:
Traps that discharge condensate at a rate dependent on the position of an internal float.  Air is removed through a thermostatic air vent.

Traps, inverted bucket:
Mechanical traps that operate on the difference in the density between steam and water.

Traps, orifice:
Traps that discharge steam at a constant rate and have no internal moving parts to alter or stem its flow.

Traps, thermostatic:
Traps that use an internal bellows, which expands when steam flows to the trap, closing the orifice.  As condensate accumulates the bellows contracts to release it.

Traveling grate:
A type of furnace in which assembled links of grates are joined together in a perpetual belt arrangement. Fuel is fed in at one end and ash is discharged at the other.

A rotary device that is actuated by the impact of a moving fluid against blades or vanes.

Turbulent flow (turbulence):
A condition where the fluid particles move in random paths rather than in continuous parallel paths.

Turn down ratio:
The lowest load at which a boiler will operate efficiently as compared to the boiler's maximum design load.

Two-way valve:
A directional control valve with two flow paths.

Uninterruptible power supply (UPS):
Provides conditioned power and battery backup for computers in the case of a power failure or brownout.

To release flow (usually directly to the reservoir), to prevent pressure being imposed on the system or portion of the system.

Unloading valve:
A valve which by-passes flow to tank when a set pressure is maintained on its pilot port.

Pressure less than atmospheric pressure.  It is usually expresses in inches of mercury (in Hg) as referred to the existing atmospheric pressure.

A device which controls fluid flow direction, pressure, or flow rate.

The speed of flow through a hydraulic line.  Expressed in feet per second (fps) or inches per second (ips).

To permit opening of a pressure control valve by opening its pilot port (vent connection) to atmospheric pressure.

A measure of the internal friction or the resistance of a fluid to flow.

Viscosity index:
A measure of the viscosity-temperature characteristics of a fluid as referred to that of two arbitrary reference fluids.

Water-cooled vibrating grate:
A boiler grate made up of a tuyere grate surface mounted on a grid of water tubes interconnected with the boiler circulation system for positive cooling. The structure is supported by flexing plates allowing the grid and grate to move in a vibrating action. Ashes are automatically discharged.

Water hammer:
Potentially damaging condition in steam pipes where waves develop on the condensate surface within a pipe as steam rushes over it.  If the peak of the wave becomes high enough to reach the roof of the pipe, the water in the wave is pushed violently to the far end of the pipe.

Condition of steam coils where condensate is not discharged at a sufficient rate to keep it from accumulating in the coil.  Filled with condensate, the coils do not transfer significant heat to the kiln.

Wobble plate:
A rotating canted plate in an axial type piston pump which pushes the pistons into their bores as it "wobbles".

A solid lignocellulosic material naturally produced in trees and some shrubs, made of up to 40%-50% cellulose, 20%-30% hemicellulose, and 20% -30% lignin.

The application of  force over a definite distance.  Work (W) = Force (F) x distance (s). Expressed in joules, ergs, and foot-pounds. The joule is exactly the amount of work done in exerting the basic metric unit of force, 1 newton, over the basic metric unit of distance, 1 metre.

Yard (yd):
Unit of length equal to 3 feet (91.5 centimetres).

An expression of the amount of product (nominal or actual) that can be manufactured from a given input of raw material. Also referred to as product recovery.