Document RjeMvzrDVxr52xgaxb29rEx6B

964 CHAPTER 67 inlet1 from exceeding a selected- value. It'is-used'primarily to prevent overload on compressor motors. valve, thermal :a valve controlled by a thermally responsive element; for example, a thermostatic expansion valve which-is -usually responsive to suction or evaporator temperature.. ' valve, water regulator: an automatic valve to control the flow of cooling water through a condenser.1; : valve seat: the stationary portion of the valve whicK when in contact with the movable portion, stops flow completely. vane ratio: in air distributing'devices the ratio of depth' of -vane to shortest opening width between two adjacent grille bars. vapor: a gas, particularly one near to equilibrium with the liquidjhase of toe substance' and which does not follow the gas laws. Usually used instead of gas for a refrigerant, and in genial for any gas below the critical temperature. vapor, saturated:'vapor in equilibrium with its liquid;-that is, when the numbers, per unit'time, of; molecules passing in two directions through tne surface dividing the two phases, are equal. . vapor, superheated:' vapor at a temperature'which' is hghr than the saturation temperature (Le., boiling point) at the existing pressure. . vapor, water: used commonly, in "air conditioning, parlance to refer to steam in the atmosphere. vapor, wet, quality of: fraction by.,weight .of vapor in mixture of.liquid and vapor.. . vapor barrier: a moisture-impervious layer applied to the sur faces enclosing a humid space to prevent moisture travel to a point where it may condense due to lower temperature. vapor lock: formation of some vapor or all vapor in a liquid line reducing weight flow as compared to weight flow in liquid phase with the same pressure differential. - vapor lock device: an orifice; capillary- tube, or other device having a restricted passage of fixed size for liquid refrigerant. It restricts flow of vapor of that same liquid to a lower rate of flow On lb per min) with the same pressure difference. .. velocity: a vector quantity which denotes at once the time rate iwl t>a direction of a line**- motion.. ; - velocity.-outlet': the average discharge velocity of. primary air being discharged from the outlet," normally measured in the plane df the opening. ` * ' velocity, room: the average sustained residual air velocity level in' the occupied tone of the conditioned space, e.g., 65, 50, 35 fpm. velocity,' terminal: the highest'sustained air stream -velocity .existing in the mixed air path at the end of the throw..' , : ventilation: the process of supplying or removing sir; by natural or mechanical means,<to or from any space. Such air may or may not have been conditioned.- = viscosity: - that property of semifluids, fluids/ and - gases by virtue of which'they resist an instantaneous change of shape or arrangement' of parts. It ts the cause of fluid -friction whenever adjacentlayers of fluid move with relation to each other.' ' viscosity, absolute: the force per unit area required to produce 1965 Guide AndDataiBook unit relative velocity between two parallel areas of fluid unit distance apart.. .- . ,> viscosity, coefficient of: as absolute viscosity. . viscosity, kinematic: the ratio of absolute viscosity to density of a fluid. volatile liquid:.one which evaporates, readily at atmospheric pressure and room temperatures. > volume, specific: the volume of a substance per unit mass'; the reciprocal of density., , -. water, jacket: in a compressor,-the water.used for cooling-the cylinder bead and/or walls.- watcr/mikeup: water supplied to replenish, as water replacing that lost by evaporation. . water, raw: in ice making, any water.used for ice making except distilled-water.', 4 ' .water cooler: evaporator for cooling water in.an indirect re frigerating system. - - water-cooling tower: an enclosed device for evaporatively cod ing' Water by contact with'air.- '- 'water-cooling tower, atmospheric: one in which the:air move ment through the 'tower is -dependent only upon atmospheric conditions. Also known as natural draft cooling tower. > .water-cooling tower/ forced draft: a.mechanical draft watercooling tower having one' or more fans located in the air entering the tower. water-cooling tower, induced draft: a mechanical draft water cooling tower having one or more located in the air leaving the tower. - - - ' - water-cooling tower, mechanical draft: one utilising one or more fans to move the air. through'the tower, the fans being an integral part of the tower. ' wax: a solid material which may separate oh cooling .of oil- refrigerant mixtures. - ' weep:drip from frozen foods. ' 1 ' wet-bulb depression: difference between dry-bulb and wet- bulb temperatures.. , ' wire-drawing: restriction of area for a,flowing fluid, causing a loss in pressure by (internal and external) friction without loss of heator performance of work;1 throttling. .work, effective:,net.mechanical energy required, by, or load imparted to,"piston of compressor. . . .work, indicated: work.equivalent of indicator card area for a reciprocating compressor or engine" wort: the unfermented infusion of malt which, when fermented, produces beer. zone, comfort' (average):the range of effective temperatures over which the majority (50 percent or more) of adults feel com fortable. (extreme): the., range of effective temperatures over which one or more adults.feel oomfortable. zone of. maximum crystal formation: temperature-range.in freezing in which most of the freezing takes place.(about 25 to 30 F for water)..' , CHAPTER 68 ABBREVIATIONS AND SYMBOLS Standard Abbreviations/ letter Symbols/ Graphical Symbols for Piping, Ductwork, Heating and Ventilating, Refrigerating; Identification of Piping by Color THIS chapter contains information regarding abbrevia tions and symbols which are of particular interest to the. engineer engaged in heating, ventilating,. refrigerating, andbbooiillienrg...p...o...i.n...t..................................................................................... air conditioning. brake horsepower.. ............................ brake horsepower-hour........................ ABBREVIATIONS FOR TEXT AND DRAWINGS British thermal unit(s)......................... X' bhp-hr Btu BLR BP BHPBHP-HR BTU Abbreviations are shortened forms of names and expressions employed in texts and tabulations, and should not generally be used as symbols in equations. Most of the following ab breviations have been compiled from a list of approved standards.M,< In general, the period has been omitted in 'all ab breviations, exeept-where the omission results in the forma tion of an EngHah word. Tens fed Orowmgi absolute..:............................................ accumulator............................................ ' ABS-, . ACCUMADPT air circuit breaker.................... ......... ACB . .. air condition (-rag, -ed, -er).................................... an- horsepower....................................... ahp AIR COND AHP alteration...:........................................ alternating current............................... ac . ALTN AC,, .'. . altitude.................................................... alt ambient................................................... imK ALT AMB American Standard.............................. Amer Std AMER STD American wire gage.-... r.v.. . AWG AWG British thermal units per hour............. British thermal units per hour (thousands)....................... Brown A Sharpe wire gage................. Btuh . MBh BAS BTUH MBH. BAS calorie. ............................................. center-to-center........ ......................... centigrade heat unit............................. centigram................................................ cal c to e chu eg BX CAL C to C . CG centimeter............................................... cm centimetor-gram-eecond (system)... cgs 'CM , : CGS . CV.. CW., COND cubic..............................: ........................ cu. cubic centimeter.................................... ce cubic feet per minute........................... cfm cubic feet per second............................ cubic inch................................................ cylinder.................................................... cfs cu ft cu in. cyl CORP. . ccw . CU, CFM cfs' CU FT : CU-IN. : CYL. ... - ampere................. ............. ;................ ampere-hour........................................... anhydrous........................................ amp . amp-far AMP - \ AMP-HR ANHYD apparatus dew point......................... apartment.............................................. approved....................... ..................... approximate............ adp , , . aDDrox ADP APT APPD APPROX atmosphere. .. automatic........ automatic check valve.................. average.:.;............... avoirdupois............... atm ATM AUTO . ACV AVG . AVDP. barometer................... barrel............................ basement.....-___ -. / Baiuae........ .... .. bill of material'.. baro bbl BARO BBL BSMT . BE B/M, The central rcapcoaibffity for this chapter is --to TC Lift, Defisiw#i aad Nomeaelatsro. degree4.............. ......................... degree Centigrade................................. degree Fahrenheit. ...-........................ degree Kelvio......................................... db deg or C F K DB DEG or. C -F..; 4 . K degree Rankine...................................... R dew point temperature....................... dpt diameter..'............................................... Hm direct current......................................... dc R DPT DIA,, . DIR COf DC. . . dry-bulb temperature:-......................... dbt iDlSCH:.; DBT 1 Abbicri*tion (or Scientific mad Eatjaeerra* Terms, Z10.1-1X1 (Americas Standards Aasociatfam). ___ * Abbreviations (or Uae oo Drawings, 232.13-1950 (American Standards * HeiricersUon Nocaenetatare (or Text and Drawings, (Proposed American Staulard B53. Part B) (Published in Stfrigtretiita Bnginmriac, Augnst 1950. p, 770). -* * - '**' -f'*- I--1 It is recommended that the abbreviation (or tba tsnpoature scale, P, C, K. R, be is srprunions (or numerical temperatures not, wherever fcaaibta, the abbreviation (or daprec be omitted S4* 08 r. 965