Document yka6NxDrJOkBa8raXMpZMeZXX

956 CHAPTER 67 nygm valve superheat: the difference.between the tem perature of the thermal bulb and the temperature corresponding. to the pressure at the outlet, or at the equaliser connection,when provided, of a thermostatic expansion valve. '' wpmriim valve snperheat change: the change in superheat- of a t>*T-m<vt-if-i> OTjMiMinn valve required to open the valve a prw^<rmimirf amount. 1 extended sarface: transfer surface, one or both sides of which are increased in area by the addition of fins, discs, or other minrw extruded: pushed out through a die. Bars of ice, metal rods, shapes and tubes are made by this method. factor of safety On pressure vessels): ratio of ultimate stress to design working stress. ' Fahrenheit: a thermometric scale in which 32 deg'denotes bees1' ing and 212 deg the boiling point of water Under normal pressure at sea level (14.696 psi). > > fan: a fan is an air-moving device comparising a wheel or blade,' and housing or orifice plate. 1 ,' fan, centrifugal: a fan rotor or wheel within a scroll type hous ing arid including driving mechanism supports for either,bat drive or dir--<nni>w*tinn fan, propeller: a propeller or diar. type wheel within a mount-: ing ring or plate and including driving mechanism supports for either belt (hive or direct connection. fan, trih--irial a propeller or disc type wheel within a cylinder and including driving mechanism supports for either belt drive or direct connection. - fan, vaneaxial: a disc type wheel within a cylinder, a set of air' guide vanes located either before or after the wheel and including driving mechanism supports for either'belt drive or direct connec-tion. fan economizer: device which prevents-the operation - of- the fan motor as a cold diffuser during the shut-down period-after the coil has been defrosted. filter: a device' to remove solid material from a fluid, filter press: a device for separating solid1 and liquid matter under pressure so that the solid residue is compressed into bri quettes to facilitate removal. fin: an extended surface to increase the heat transfer area, as metal sheets attached to tubes. ' 7// flammability: a material's ability to, burn, flare fitting: a type of soft-tube connector which involves^the flaring of the tube to provide a mechanical seal/ flash chamber: separating tank placed between the expansion valve and evaporatin' in a refrigeration system to separate and bypass any flash gas formed in tire expansion valve. ' - flaeh gu: the gas resulting from the instantaneous evapori-. tion of refrigerant in a pressure-reducing device' to c0ol.the.re7 frigerant to .the evaporation temperature obtaining at the re-' duced pressure. . >(1. finch pant: temperature of combustible material, as -oil, .at which there is a sufficient vaporisation to ignite the vapor, but, not sufficient vaporisation to support combustion of the material. flotation fa method of treating by floating in a liquid.. An method in which ice floats away from the surface on which it hasbeen frozen. . ..., flow, laminar or streamline: fluid flow in .which each fiuidi particle moves in a smooth path substantially -parallel to the: paths followed by ail other particles. - flow, turbulent: fluid flow in which the fluid moves transverely as well as in the direction of the tube or pipe axis, as opposed-to' streamline or viscous flow. fluid: gas, vapor,- or liquid. v.-. - , -1 fluid, primary: the refrigerant, to HiatingufaJ* from secondary fluid or brine. I. -. fluid, secondary: fluid cooled by the-.refrigerant;in indirect method of refrigeration. foaming: the formation of a foamor froth of.'ah oil^refngerant' mixture due to rapid boiling out of.the refrigerant dissolved th the' o3 when the pressure is suddenly reduced-THu3 occurs' when' the' eomprmsor starts operating and, if large quantities of refrigerant' were dissolved large quantities of oil may bod out and be carried through the refrigerant lines. - fog: suspended liquid droplets generated by,condensation from the gaseous to tbehquid state, or by breaking up a'llqyid into a: dispersed state, such as by splashing- foaming, and atomizing' 1965 Guide And Data Boole force: the action on a body which tends to change its relative condition as to rest or motion. free area: the total minimum area of the openings in an air inlet or outlet through which air can pass. freeze-up: failure of a refrigerating unit to operate normally due to formation of ice at the expansion device. A valve may freeze shut or open, causing improper refrigeration in either case. On a coil, frost formation to the extent that air flow stops or is severely restricted. 1 freezer: in cold storage, an insulated room kept below 30 F-- see (a) carrying frtezer, (b) thorpfreezer. Any device for freezing perishables. freezer,' carrying: cold storage freeze room, generally kepi between -- 20 and 20 F, to receive and hold frozen goods. " freezer, sharp: cold storage freezer room, generally kept at from --40 to -- 10 F, to receive unfrozen goods and freeze them. freering method, refrigerated plate: heat transfer through the direct contact of refrigerated plates with the packaged product. freezing method, tray: a method of freezing food by subjecting it to moving refrigerated air; the food is arranged on shallow trays, which are placed in portable racks and put in an insulated chamber through which the air is blown. freezing point: temperature at which a given liquid substance will solidify or freeze upon removal of beat. Freezing point for water is 32 F. freezing time: time for any complete freezing process to take place. frost back: the flooding of liquid from an evaporator into the suction line accompanied by frost formation on suction line in most cases. frozen food: any food in which the contained water is in* the solid form. fumes: smoke; aromatic smoke; odor emitted,'as of flowers; a smoky or vaporous exhalation, usually odorous, as that from concentrated nitric acid. The word fumes is so broad and inclu- sive that its usefulness as a technical term is very limited.. Its principal definitive characteristic is that it implies an odor.-The terms vapor, smoke, fog, eta., which can be more strictly defined, should be used whenever possible. Also defined as solid particles generated by condensation from the gaseous state, generally after volatilization from molten metals, etc., and often accompanied by a chemical reaction such as oxidation. Fumes flocculate and sometimes coalesce. furnace: that part of a boiler or warm air h-*tjng plant in which combustion takes place. Abo a complete heating unit for trans ferring heat from fuel being burned to the air supplied to a heat ing system. > fusible plug: a device having a predetermined melting tempera ture member for the relief of pressure. gage (gauge): instrument for measuring pressure or liquid level. Also arbitrary scale of measurement for sheet metal thickness, wire and drill diameters, etc. gage glass: device for showing a liquid level. n: usually a highly superheated vapor which, within acceptmita of accuracy, satisfies the perfect gas laws, gas, inert: a gas that neither experiences nor causes chemical reaction nor undergoes a change of state in a system or process; eg., nitrogen or helium with a volatile refrigerant. gas, noncandensable: gas in a refrigerating system .which does not condense at the temperature and partial pressure at which it exists in the condenser, and therefore imposes a higher head pres sure on the system. generator: basic part of absorption system; a still provided with means of twfang used to drive refrigerant out of solution! glazing: of foods, freezing a coat of ice on frozen food by dip ping in water, the latent heat of the ooat being absorbed inwards. graduated acting: term applied to a control instrument or de vice which functions to give throttling control; that is, operates between full-on and fuil-off position. gravity, specific: density compared to density of standard material; reference usually to water or air; . grille: a louvered or perforated covering for an air passage open ing, which can be located in the sidewall, ceiling, or floor. halide torch: a flame tester generally using alcohol and burning with a bhie flame; when the m*rKwg tube draws in halocarbon refrigerant vapor, color of flame changes to bright green. - head.'dynamic or total: in flowing`fluid, thesum of the static and velocity heads at the point of measurement. Terminology head, static: the static pressure of fluid expressedin terms of the height of a column of the fluid, or of some manometric fluid, which it would support. 1 ; bead, velocity: in a Sowing fluid, the height of the fluid or of mamametric fluid equivalent to kta velocity pressure. . heat: the form of energy that is transferred by virtue of a' temperature difference. . 1- heat, latent: change of enthalpy during a change of state.- With' pure substances, latent heat is absorbed or rejected at constant pressure. i heat, sensible: heat which is associated with' a change in textf- perature; 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 quantitityof heat required.to raise the temperature of a given mass of any substance one deg to the quantity required to raise the temperature of an equal mm of a standard substance (usualy water at 59.F) one deg. . heat, vital: heat generated by fruits and vegetables in storage, due to ripening. _. beat exchanger: a device spedfieaify designed to transfer heat between two physically separated fluids. Also, see Heat .inter changer. heat of fusion: latent heat involved in changing-between the 6oiid and the liquid states. ....... ... beat of reaction: heat per unit mass or per mole of one of the reagents or products of reaction in a, chemical. reaction; exo thermal if given off, endotbermal if absorbed. - heat of the liquid: enthalpy of.a arbitrary zero. of liquid above an - heat of vaporization: latent beat involved in the change between liquid and vapor states. treat pump: a refrigerating system employed to transfer heat into a space or substance. Tne condenser provides the heat while the evaporator is arranged to pick up heat from air, water, etc. By shifting the flow of air or outer fluid a heat pump system may alro be used to cool the space. .. ,, heat transmission any time-rate of heat' flow; usually refers to conduction, convection and radiation oombined. 1: heat transmission coefficient: any one of- a- number 'of co efficients used in the calculation of beat transmission by conduct tion, convection, and radiation, through various materials^and structures. (See thermal conductance, - thermal conductivity, thermal resistance, thermal resistivity, thermal transmittance,; etc.) heating, regenerative: a heat transfer process for utilizing beat which must be rejected or absorbed in one part of a cycle, to per? form a useful function in another part of the cycle. - beating system, high-pressure steam: a steam heating system' employing steam at pressures above 15 psig. heating system, high-temperature water: a heating system in' which water having supply temperatures above 350 F is used as a' medium to convey beat from a central boiler, through a piping system, to suitable heat distributing means. - - heating system, hot water: a heating system-in'which water having supply temperatures less than 250 F is used aa a medium1 to convey beat from a central boiler, through a piping system,--to suitable heat distributing means. .. . heating system, low-pressure steam: a steam system employing steam at pressures between 0 and 15 psig. heating system, low-temperature water: same aa hat-water heating system. . heating system, medium-temperature water: a heating system m which water having supply temperatures between 250 JP and350 F is used as a nwiitm to convey heat from a central boiler,* through a piping system, to suitable heat distributing means.T heating system, panel: a beating system, in which .heat is> transmitted by both radiation and convection from panel -sur faces to both air and surrounding surfaces. - - i heating system, perimeter warm air: a warm air beating systemof the combination panel and convection type. Warm air.ducts onbedded in tire concrete slab of a basementiess bouse, around > the perimeter, receive heated air from a furnace and deliver it to the heated space through registers placed in|or near- the.floor. Air ts returned to tho furnace from registers-hear the filing <t heating system, radiant: a heating system in which only, the heat radiated from panels is effective.In providing.$he, Keating, requirements. The term radiant heating is frequentiy_used.to in-, elude both panel and radiant heating} heating system, split: a system in which the heating is accom 957 plished .By means of radiators or convectors supplemented by mechanical circulation of air (heated or unbeated) from a central point. Ventilation may be provided by the system. heating system, steam: a heating,system in which beat is transferred from the boiler or other source of beat to the heating unite by means of steam at, above, or below atmospheric pressure. heating system, vacuum: a two pipe steam heating system equipped with the necessary accessory apparatus which will per mit operating the system below atmospheric pressure when de sired. heating system. Taper: a steam heating system which operates under pressures at or near atmospheric and which returns the condensate to the boiler or receiver by gravity. ....... beating system, warm air: a warm air beating plant consisting of a heating unit (fuel-burning furnace) enclosed in a casing,'from which the heated air is distributed to various rooms ofthebuild^ ing through ducts. heating unit, electric: a structure containing one or more heat ing elements, electrical terminals or leads, electric insulation^ a frame or casing, all assembled together in one unit. high capacity tmit: an air distribution unit consisting' of a factory-made assembly of dual duct modulating dampers-and integral volume control station together with a temperature mix ing station to supply air volumes greater than 2000 cfm from an external source. These units are designed for furred-in applica tion and distribution ducts to provide aound attenuation and air delivery to the occupied room. high pressure unit: an air distribution-unit consisting, of a factory-made assembly with either a dual duct modulating damper (or a single duct pressure reducing damper), aa integral volume controller together with temperature' mixing and sound attenuation stations, which supply air volumes up to approxi mately 2000 cfm and static pressures greater than 0.40 in..water from an external source. Units may be designed for a furred-in application in a plenum or for exposed installation in the spa$e with or without an enclosure. high side: parts of a refrigerating system subjected'to con denser pressure or higher. . horsepower: unit of power in foot-pound-eecond system, work done at the rate of 550 ft lb per sec,- or 33,000 ft lb per min. hot gas line: a line used to convey discharge gas from the com pressor. , humidifier: a device to add moisture to air., humidifier, central: a-device which humidifies air-to.be cir culated through ducts in an air-conditioning system. - >' humidifier, roam-spray type: an'air humidifier which sprays water directly into tire room. "* ' . humidify: to add water vapor to the atmosphere; to aidd water vapor or moisture to any material. ( humidifying effect: the latent heat of vaporization of water al the average evaporating temperature time* the weight of water evaporated per unit of time. *' hnmjdistat: a regulatory device, actuated' by changes'in humidity, used for the automatic control of relative humidity. humidity: water vapor within a given spate- . . . humidity, absolute: the weight of water vapor per unit volume! humidify, percentage: the ratio of the weight of water vapor associated with a pound of dry air to the weight of water-vapor associated with a pound of dry air saturated at the tempera^ tore. humidity ratio: see kximidity, specific. humidity, relative: the ratio of the mol fraction of water vapor present in the air. to the mol fraction of. water vapor present in saturated air at ure same temperature and barometric pressure; approximately, it equals - the ratio of the partial pressure or density of the water vapor in the air, to the saturation pressure or density, respectively, of water vapor at the tame temperature.. humidify, 6pedfic: weight of water.vapor (steam)'associated with one lb weight of dry air, also humidity ratio', j hydrolysis: the splitting up of compounds by reaction with water; e^., reaction of diemarodifluoromethaaa or methyl chloride with water. In which cases acid materials ore formed. ' hydrometer: an instrument which,'by the extent.of its. sub! mergence, indicates the specific gravity of the' liquid in* which'it floats. ' ' hydronics: the science of heating and cooling'with liquids.'' hygrometer: instrument-responsive'to humidity conditions (usually relative humidity) of the atmosphere.-,.. .. v_Si;