<-- PREVIOUS | Back to Alphabetical Index | NEXT -->

g Gram; a metric unit of weight. One ounce U.S. (avoirdupois) is about 28.4 grams.

g/kg Grams per kilogram; an expression of dose used in oral and dermal toxicology testing to indicate the grams of substance dosed per kilogram of animal body weight. Also see "kg" (kilogram).

GALVANIC An electrochemical action due to a couple made up of dissimilar metals.

GALVANIC SERIES A list of alloys arranged according to their corrosion potentials in a given environment.

GALVANIC COUPLE The connection of two dissimilar metals in an electrolyte that results in current flow through the circuit.

GANG STIRRERS A mechanical mixer that mixes several water samples concurrently.

GANGUE The earthy material remaining from ore beneficiation.

GAPHITIC CORROSION Corrosion of cast iron in which the iron constituent is corroded, leaving the graphite intact.

GAS Usually a highly superheated vapor which, within acceptable limits of accuracy, satisfies the perfect gas laws.

GASKET A resilient or flexible material used between mating surfaces of refrigerating unit parts or of refrigerator doors to provide a leakproof seal.

GATE VALVE A valve used to control the flow of water consisting of a gate or a wedge at right angles to the water flow that can be raised or lowered into a passageway. Used chiefly where the valve is to be operated either wide open or closed.

GAUGE MANIFOLD A device constructed to hold compound and high pressure gauges and valved to control flow of fluids through it.

GAUGE, COMPOUND Instrument for measuring pressures both below and above atmospheric pressure.

GAUGE, HIGH PRESSURE Instrument for measuring pressures in range of 0 psig to 500 psig.

GAUGE, LOW PRESSURE Instrument for measuring pressures in range of 0 psig and 50 psig.

GAUGE, VACUUM Instrument used to measure pressures below atmospheric pressure.

GEAR PUMP Two gears intermesh to pump fluid.

GEARBOX Power transmission unit on cooling tower which provides a right angle turn from motor shaft and couplings to gear down motor speed thereby generating power of air movement from the fan. Transmission unit which reduces RPM from the power source through a system of gears to the design speed for the fan to produce optimum air flow.

GELS Lumps of dry polymer that form during improper solution preparation.

GENERAL CORROSION A form of corrosion that is distributed widely and more or less uniformly over a metal surface.

GENERAL EXHAUST A system for exhausting air containing contaminants from a general work area. Also see "local exhaust".

GIRT (See Horizontal Tie)

GLOBE VALVE Valve used to control the flow of water consisting of a plug or disk which is raised or lowered into a tapered hole called a "seat". Used chiefly when the flow of water is to be restricted or throttled.

GOUGING Semilocalized depressions in the form of deep, longitudinal cavities typically caused by caustic attack in steam generating tubes. Also occurs by acidic attack in return lines.

GPD Gallons per Day

GPH Gallons per Hour

GPM Gallons per Minute

GRAB SAMPLE A sample taken at a random place in space and time.

GRADIENT The change in pressure or temperature required to move a valve needle from the closed to the open position at which the valve delivers its rated flow. In compression springs it is the load required per unit of deflection usually expressed in pounds per inch.

GRAIN A measurement of weight equil to 1/7000 of a pound. The water softener industry uses grains for measuring hardness of water and grains for total capacity.

GRAINS CAPACITY Refers to the amount of hardness minerals that will be removed by a water conditioner mineral or resin within a specified amount of time, or by a specific quantity or resin (see HIGH CAPACITY RESIN).

GRAIN GROWTH Increase of grain size in metals. In boiler tubes, grain growth indicates overheating to temperatures above the A₃ point (see Transformation Temperature) for extended periods of time. Concurrent straining or decarburization influences the temperature at which it occurs.

GRAIN SIZE Expressed as the number of grains per unit area. Usually grain size is expressed as a number and is determined at 100 magnifications. On the ASTM scale, numbers round from 1 (largest) to 8 (smallest).

GRAINS PER GALLON (gpg) A measure of proportion by weight of compounds or ions to a gallon volume of solution. Expressed in weight units of grains (7000 grains equal 2 pound avoirdupois) 1 gpg equals 17.1 ppm.

GRAM-ATOM A collection of atoms of an element whose mass, in grams, is equal to the element’s atomic weight.

GRAM-MILLIEQUIVALENTS The equivalent weight in grams, divided by 1,000.

GRAM-MOLE OR MOLE The number of grams of a substance equal to the atomic weight of an element or the molecular weight of a compound.

GRAM-MOLECULE A collection of molecules whose mass, in grams, is equal to the compound’s molecular weight.

GRANULATED ACTIVATED CHARCOL (GAC) Wood, bone or anything containing a high percentage of carbon, that has been subjected to destructive distillation, to produce charcoal. GAC removes contaminants by adsorption. Organic contaminants adhere to GAC much like a magnet adheres to a metal surface but can be removed by high temperature.

GRAPHITIZATION In cast iron, the selective loss of iron that leaves the metal with a weak structure of graphite and iron oxides.

GRAVEL SUPPORT BED Gravel in various sizes (one of which may actually be coarse sand) is placed above the underdrain so that the support bed will contain the resin during the softening run. The coarsest material is at the bottom and the finest at the top. The support bed contributes greatly to the uniform distribution desired.

GRAVITATIONAL THICKENING Producing a concentrated solids mass using gravity to induce particles to settle and compress.

GREEN LIQUOR The liquor resulting from dissolving molten smelt from the kraft recovery furnace in water.

GREENSANDS Naturally occurring materials composed primarily of complex silicates, which possess ion exchange properties.

GROOVING Form of corrosion whereby ruts or "grooves" are formed in the affected surface. Also see Gouging.

GROUNDWATER The supply of freshwater under the earth’s surface in an aquifer or soil that forms the natural reservoir for man’s use.

H

H-O-A Switch A typical control switch on a controller. H indicates Hand or manual operation, O indicates Off and A indicates Automatic operation.

HALIDE TORCH Type of torch used to detect halogen refrigerant leaks.

HANDRAIL A horizontal or sloping rail placed along an access way or at the edge of a platform. Usually at 3’-6’ above the walkway or floor.

HARDNESS A characteristic of water generally accepted to represent the total concentration of calcium and magnesium ions. Note: Originally hardness was understood to be the capacity of a water for precipitating soap. Soap is precipitated chiefly by calcium and magnesium ions commonly present in water but my also be precipitated by ions of other polyvalent metals, such as iron, manganese and aluminum, and by hydrogen ions. Hardness was originally measured by the amount of soap required to produce a stable lather. Measurement is usually made on a water sample, the alkalinity of which has been adjusted to eliminate the effect of hydrogen ions. Hardness is expressed fundamentally in terms of the chemical equivalents of metal ions capable of precipitating soap. It has commonly been expressed in terms of the equivalent amount of calcium carbonate.

HARDNESS The concentration of calcium and magnesium salts dissolved in water.

HARDNESS EXPRESSED AS CALCIUM CARBONATE Using calcium carbonate as the common denominator.

HARDNESS LEAKAGE The small amount of hardness still present in the softened water when a softener is working perfectly. It is affected by high total dissolved solids and the amount of salt used in regeneration.

HARDNESS SENSOR A device which detects when a softener needs regeneration. It sends an electrical signal to initiate regeneration.

HAZARD WARNING Any words, pictures, symbols, or combination thereof appearing on a label or other appropriate form of warning that convey the hazards of the chemical(s) in the containers(s).

HAZARDOUS CHEMICAL Any chemical which is a physical hazard or health hazard.

HAZARDOUS DECOMPOSITION PRODUCTS Hazardous materials that may be produced in dangerous amounts if the subject material is exposed to burning, oxidation, heating or allowed to react with other chemicals.

HAZARDOUS INGREDIENTS By definition, a hazardous ingredient is a substance or form of a substance in mixture, in sufficient concentration to produce a flammable vapor or gas, or to produce acute or chronic adverse effectes in persons exposed to normal use or predictable misuse. These include, but are not limited to, substances listed in 29 CFR 1910.1000, Tables Z-1, Z-2, and Z-3, the ACGIH list of TLV’s and any confirmed or suspect carcinogens, toxics, corrosives, as well as any combustible liquid, compressed gas, explosive, flammable, organic peroxide, oxidizer, pyrophoric, unstable (reactive) or water reactive chemical.

HAZARDOUS MATERIAL A substance or material capable of posing an unreasonable risk to health, safety and property.

HAZARDOUS SUBSTANCE A material which if spilled to the environment in reportable quantities, must be reported to the EPA or Coast Guard under CERCLA regulations.

HAZARDOUS WASTE A waste that meets defined chemical characteristics (ignitability, corrosivity, reactivity, or EP toxicity) or consists primarily of chemicals listed in EPA regulations at 40 CFR 261.20261.33. These regulations are written to enforce the requirements of the Resource Conservation and Recovery Act.

HDPE An abbreviation for high density polyethylene, which stands up better to attack by some chemicals than standard polyethylene.

HEAD PRESSURE Pressure which exists in condensing side of refrigerating system.

HEADER In a counterflow tower, the main pipe carrying hot water to a series of laterals for distribution over the fill material. In a crossflow tower, the main pipe carrying hot water to each cell hot water distribution basin longitudinally. Crossover pipe carries the hot water laterally within the cell.

HEADLOSS The reduction in liquid pressure associated with the passage of a solution through a bed or exchange material; a measure of the resistance of a resin bed to the flow of the liquid passing through it.

HEALTH HAZARD Acute or chronic health effects may occur in persons exposed to the chemical.

HEART WOOD The wood extending from the pith to the sap wood, the cells of which no longer participate in the life processes of the tree. Heart wood may contain phenolic compounds, gums resins, and other materials that usually make it darker and more decay resistant than sap wood.

HEAT The form of energy that is transferred by virtue of a temperature difference.

HEAT CAPACITY The heat capacity of water, Cp , is usually taken as 1 BTU/Lb-§ F. Heat capacity is synonymous with specific heat or specific heat capacity.

HEAT COMPRESSION The heat added to the refrigerant gas, resulting from work done by the compressor in pumping it from suction pressure to the discharge pressure level; it is the difference in enthalpy of the refrigerant gas at these two conditions.

HEAT EXCHANGE A device for transferring heat from one substance to another. Heat transfer can be by direct contact, as in a cooling tower, or indirect, as in a shell and tube condensor.

HEAT EXCHANGER A device used to transfer heat from a fluid flowing on one side of a barrier to a fluid or fluids flowing on the other.

HEAT LOAD The amount of heat dissipated in a cooling tower measured in BTU’s; is equal to the weight of water circulated per unit time multiplied by the cooling range. BTU per hr. = (GPM) (500) (HWT-CWT).

HEAT OF COMPRESSION The heat of compression is the energy added to the refrigerant by the compressor.

HEAT OF FUSION Latent heat involved in changing between the solid and the liquid states.

HEAT OF THE LIQUID Enthalpy of a mass of liquid above an arbitrary zero.

HEAT OF VAPORIZATION Latent heat involved in the change between liquid and vapor states.

HEAT PUMP A refrigerating system employed to transfer heat into a space or substance. The condenser provides heat for the space while the evaporator is arranged to pick up heat form air, water, etc. By shifting the flow of air or other fluid, a heat pump system may also be used to cool the space.

HEAT RATE An expression of heat conversion to power, given in Btu/kWh. Theoretical conversion is 3413 Btu/kWh.

HEAT TRANSFER The movement of heat from a hotter medium to a cooler medium, usually through a metal surface.

HEAT TRANSFER COEFFICIENT The heat transfer coefficient is a factor which relates the rate of energy flow between different substances. The heat transfer coefficient is determined by the properties of the contacting substances at their interface and does not change with changing loads or operating conditions.

HEAT TRANSFER COEFFICIENT RATIO ACTUAL The actual heat transfer coefficient ratio is the ratio of the heat transfer coefficient in the current and impact columns of the Energy Management Status Report to the actual heat transfer coefficient in the base case.

HEAT TRANSMISSION Any time-rate of heat flow; usually refers to conduction, convection and radiation combined.

HEAT, LATENT Change of enthalpy during a change of state. With pure substances, latent heat is absorbed or rejected at constant pressure.

HEAT, SENSIBLE Heat which is associated with a change in temperature; specific heat exchange of temperature; in contrast to a heat interchange in which a change of state (latent heat) occurs.

HEAT, SPECIFIC The ratio of the quantity of heat required to raise the temperature of a given mass of any substance one degree to the quantity required to raise the temperature of an equal mass of a standard substance (usually water at 59 F) one degree.

HEATING COIL A heat transfer device which releases heat.

HEMOLYSIS A process by which a bacterial species utilizes blood in its metabolism and destroys red blood cells.

HEMATOPOIETIC Pertaining to the production of blood cells.

HENRY’S LAW An expression for calculating the solubility of a gas in a fluid based on temperature and partial pressure.

HEPATOTOXIC Chemicals which may cause damage to the liver.

HERMETIC SYSTEM Refrigeration system which has a compressor driven by a motor contained in compressor dome or housing.

HETEROTROPHIC ORGANISM Organisms that are dependent on organic matter for food.

HIDE OUT When a softener has been regenerated, rinsed until soft an then not used for some time and later put into service, the first few gallons may not be soft.

HIGH CAPACITY RESIN It is a manufactured material in the form of beads or granules, which can be described as having the power to "take" or "give off" (trade or exchange) hardness-forming ions for softness-forming ions and the reverse cycle thereof. It is sometimes called Zeolite or Ion Exchange resin.

HIGH PRESSURE CUT-OUT Electrical control switch operated by the high side pressure which automatically opens electrical circuit if too high near pressure or condensing pressure is reached.

HIGH SALTING Using 15 pounds of salt or more to regenerate each cubic foot of resin is called "high salting." Doing so will produce a better quality of soft water and 1/3 more capacity as compared to "low- salting" of about six pounds per cubic foot of resin.

HIGH SIDE Parts of a refrigerating system subjected to condenser pressure or higher.

HIGH SIDE FLOAT Refrigerant control mechanism which controls the level of the liquid refrigerant in the high pressure side of mechanism.

HIGHLY TOXIC A chemical that has a median lethal dose (LD₅₀) of 50 milligrams or less per kilogram of body weight when administered by mouth to albino rats weighing between 200 and 300 grams each.

HIGHLY TOXIC A chemical that has an LD₅₀ of 200 mg/kg or less when applied by continuous contact for 24 hours with the bare skin of albino rabbits weighing between two and three kilograms each.

HIGHLY TOXIC A chemical that has a median lethal concentration (LC₅₀) in air of 200 ppm by volume or less of gas or vapor, or 2 milligrams per liter or less of mist, fume or dust when breathed continuously for one hour by albino rats weighing between 200 and 300 grams each.

HINDERED SETTLING Particle flow patters interfere with each other, slowing down the overall settling velocity of particles.

HMIS Hazardous Materials Identification System, established by the National Pain and Coating Association.

HOMOGENIZE To reduce to small, uniformly sized, and evenly distributed particles.

HORIZONTAL TIE Framework member; a load-bearing horizontal connecting member in the tower framework.

HORSEPOWER A unit of power equal to 33,000 foot pounds of work per minute. One electrical horsepower equals 746 watts.

HORSEPOWER PER TON, THEORETICAL The theoretical horsepower per ton is the horsepower required to run the refrigeration compressor at 100% compressor efficiency to produce a ton of refrigeration.

HOSE BIB An outside plumbing connection for attaching a hose.

HOT GAS BYPASS Piping system in refrigerating unit which moves hot refrigerant gas from condenser into low pressure side.

HOT GAS DEFROST A defrosting system in which hot refrigerant gas from the high side is directed thorough evaporator for short period of time and at predetermined intervals in order to remove frost from evaporator.

HOT PROCESS SOFTENING Chemical precipitation softening at 212-250° conducted in a pressure vessel under 5-15 psg.

HOT WATER TEMPERATURE The temperature of circulating water entering the distribution system in degrees Fahrenheit.

HOT ZEOLITE A sodium zeiolite softener operated at a temperature of 215 to 220° F. This unit will usually follow a hot lime softener.

HP Horsepower.

HUMIDIFICATION The addition of water vapor to air.

HUMIDITY, ABSOLUTE Amount of water vapor contained in the air at a given condition usually expressed in pounds of water per pounds of dry air.

HUMIDITY, RELATIVE Ratio of water vapor pressure in the air to the saturated vapor pressure at the same temperature usually expressed as a percentage.

HUNTING (Refrigeration System) The alternated overfeeding and starving of the refrigerant liquid flow to the evaporator, thereby producing sustaining cyclic changes in pressure and temperature of the refrigerant gas leaving the evaporator.

HVAC An abbreviation for heating, ventilating and air conditioning. Sometimes shown as hvac/r, with the r standing for refrigeration.

HYDRAULIC CLASSIFICATION The rearrangement of resin particles in an ion exchange unit. As the backwash water flows up through the resin be, the particles are placed in a mobile condition wherein the larger particles settle and the smaller particles rise to the top of the bed.

HYDROGEN A very light gaseous material. In ionic form in water it represents the degree of acidity of a solution.

HYDROGEN CYCLE A complete course of cation exchange operation in which the adsorbent is employed in the hydrogen or free acid form.

HYDROGEN CYCLE SOFTENING Softening by cation exchange where calcium and magnesium ions are exchanged with hydrogen ions. Exchange resin is regenerated with a solution of acid, normally sulfuric acid.

HYDROGEN EMBRITTLEMENT Attack resulting from the diffusion of atomic hydrogen into steel, reacting with carbon or other atomic hydrogen at the grain boundaries. The steel is decarburized; the resultant formation of methane and molecular hydrogen builds up high pressures that cause discontinuous, intergranular cracks in the metal.

HYDROGEN SULFIDE A vile smelling gas. It forms a weak acid in water solution.

HYDROGEN ZEOLITE A cation exchange resin bed, regenerated with acid, which replaces other cations in solution with hydrogen ions. This process eliminates alkalinity from the treated water.

HYDROLYSIS A chemical process of decomposition involving the splitting of a bond and the addition of the elements of water.

HYDROPHILIC Having an affinity for water. Its opposite, non-water wettable, is hydrophobic.

HYDROXIDE A highly alkaline radical in water solutions.

HYDROXYL ION The OH ion, which is the strongest base in water solution.

HYGROSCOPIC Readily absorbing and retaining water.

HYPALON® A chlorosulphonated polyethylene used for pump diaphragms, seals and flexible seats. Trade name of DuPont.

HYPERBOLIC TOWER An evaporative type natural draft cooling tower of hyperbolic shape which depends on natural draft for air movement through the tower. Can be either crossflow or counterflow type of tower also Natural Draft Tower, or Atmospheric Tower.

HYPHA A single filament or strand of the vegetative portion of the fungus.

<-- PREVIOUS | Back to Alphabetical Index | NEXT -->

Home  •  Privacy Policy  •  Español