Document GzK4QZDz0R6D3xDyxpaXjodyv

TECHNICAL BRIEFS ENGINEERING DEVELOPMENTS HCR| ABROAD OIGESTED FOR BUSY POWER , REVIEWED IN THIS ISSUE VALVES AND PIPES Volva Chorocterivtki and Proem Control Liquid Flow Chorocteriif kl of 0 Pipvlin* and e Control Voir* Control-VoNe Body Datign OIL USES Fuel Oil in the Steel Industry MainttnoiKO of Clectrkal Oil* Oil Clerilkatlan in Steal Plante High-Temperature Lubrkonti Soaring Soali RUST PREVENTION Rutt Preventives Maintain Steel Water Wortu Maintenance ` "Dlraethns lor ordering papers art given an poge iJO" Opm ter pipe vetociry Cqwlvaient leet at pipe LiQvtd npv Porter* Pressure Ortp eerast H-0 SOOOvwve M+t* n>p)i ju AW torwafes vn 4*n0 #w one * ppm t Mm Stot9P/+c ***** errawv qv from . f**t ot&f mo tfv-ctn PmmtSmv Slaom 85 to lOOpSip Linear voivv. Eqvol X volvt wetei Steam i4/ 44 1/4 ip MOP 140F 100 P>o PF 14 P MOP I40F 29 olo SBMS 5 toe 6 S2| z t| i t|| Vttvfitif M-0 3000 sorts - Cpm \ 1 2Comparison between the Hnoar and equal percentage valves shows on o load where water changes 30 F and steam 75 pslo Network ehort helps site valves where flow rate, velocity viscosity, specific grovlty, equivalent pipe length ore V VALVES AND PIPES Valve Characteristics akd Process Control, by N B Nichols and J G Ziegler, Taylor Instrument Co's. This discussion of various valves tells how their choracteriatics fit them for process control. Included are ratio, throttle, Vnotch and beveled-diak types. For in* stance, the so-called poppet valve is o( single* or double-seated beveled-ditk design. Their nature--globe valves with sliding steins instead of a threaded, hand-operated stem--permits easy use with automatic controls. But this dats of valve has essentially a linear flow-lift characteristic; its effective opening area increases in almost direct propor* lion to the lift of the valve from the seat. Ideal control for oil processes is not necessarily linear so this valve clou is limited to those processes where pure linear control applies. A second valve class, one with* an equal percentage characteristic, draws its name from the fact that the valve disk is so shaped (hat 0 given lift at any opening Increases effective opening area o fixed propor tion of the total existing. A comparison 01 these valvee is shown in Fig. A goo-fired oil heater--one sample process of many selected by the authors --maintains a constant outlet-oil tem perature by operating a valve in a fuel gas line to the burners. From an an alysis of this process and the others, the authors formulate a general rule on valve selection. In brief, these rules make up a simple guide for determining the most desirable control valve for a given application. Volvo characteristics con be over looked if (1) controller sensitivity is high (2) period of oscillation is short (3) maximum range of load Is less than two to one. An "equal percentage valve" does nut apply if (I) controlled medium carries solid porticles or will deposit scsle (2) maximum load range is greater than about eight to one (3) major loadchange calls for a linear valve (4) val*.( lag accounts for most of effective proe-. ess lag. IS4 Paper No. 48-2-1- * Ijquid Flow Characteristics or * Pipe Lire ano a Control Valve, bfOtto Kneisel, Hemmel-Dohl Co. SImI of all conirol valves by slide rults r alignment charts, based on pressor? drop across them, disregards the eh*1' oclerislics of the line in which the *al* Is to ho installed. This paper sets op network chert to solve any specific cofl' Uol-valve problem in a liquid** ^ lem requiring pipe else, valve oise. prtf* sure drop ocrosa the line and across ",e valve, flow rangeability and fl* e^*r acterislics. Basic data necessary lf * lariing point are: (I) flow rate, IP* (2) specific gravity of liquid in* (3) viscosity (4) equivalent length 128 <7201 POWER November ,M NAVALON lasts longer because it contains more lubricant and retains more lubricant Navalon is important news to you . . . because it is a superior new packing for cold liquid service ... another development of the J-M Research Laboratory. Navalon--mode of ramie, the strongest of all natural fibers--outlasts other packings because it contains more lubricant to begin with . . . and because it retains more lubricant in service. Navalon is abrasive-free and rot-resistant . ; ; delivers outstanding performance on pumps, elevators, accumu lators, presses, and reciprocating rods and plungers . v operating against fresh or salt water, brine, cold oil aod other liquids. Navalon, the new ramie packing for cold liquid service, is another example of the continuing research at J-M <hat brings you better, longer-wearing packings for every service condition. See your Distributor--or write JohnsManville, Box 290, New York Id, N. Y. Johns-Manville A t'Owt * Nov.mb.. 1940 I*j < 11 ii IS f)