Calculation of Kv value Medium Saturated Liquids steam RECOMMENDED FLOW VELOCITIES AT THE INLET OF VALVE, FOR THE SIZING OF NOMINAL PIPE SIZE :

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1 DT SHEET FOR CONTROL VLVES VLVE SIZING The valve sizing is based on the calculation of the Kv coefficient. The Kv represents the quantity of water, expressed in cubic meters (m3) at 15ºC, that flows through the valve with a pressure drop of 1 bar, in one hour period. The formulas, below indicated, allow the Kv calculation in accordance with the type of fluid and it s operating condition. fter the Kv calculation, the corresponding Kvs is available from the valve data sheet. If real operating data have been used for the calculation, as a rule the calculated Kv should be around 70% to 80% of the selected valve Kvs in order to guaranty proper regulation of maximum flow rate at the given operating conditions preventing that sometimes some precautionary additions will result in undesirable valve over sizing. t the same time it is necessary to check whether the minimum flow rate can be even regulated or not considering the chose valve rangeability. For critical applications,(critical flow velocities, for example), noise prediction, etc, please fill the data sheet available in the next page and submit it to our technical department for proper selection using our software. a) b) Pressure Drop P Dp P Dp Calculation of Kv value Medium Saturated Liquids steam d1 Kv Q1 Dp 1000 Q Kv,4 Dp P Q Kv 11, Q3 Kv 514 Gases d T Dp P Q Kv 3 d T 57 Remarks: For superheated steam and other fluids please consult. a) Subcritical pressure drop: downstream absolute pressure more than 50% of the absolute upstream pressure in the valve. b) Supercritical pressure drop: downstream absolute pressure is equal or less than 50% of the upstream absolute pressure in the valve. Kv Flow coefficient m3/h Upstream absolute pressure bar P Downstream absolute pressure bar Dp Pressure drop ( P) bar Q1 Flow rate m3/h Q Flow rate Kgs/h Q3 Flow rate N.m3/h (0ºC 1013 mbar) d1 Specific weight of liquid Kg/m3 d Specific weight of gas Kg/m3 T bsolute temperature (T=73 + t ºC) ºK t Fluid temperature ºC RECOMMENDED FLOW VELOCITIES T THE INLET OF VLVE, FOR THE SIZING OF NOMINL PIPE SIZE : Liquids :,5 m/s ; Gases : 0m/s ; Saturated steam : 5 m/s ; Superheated steam : 50m/s 437

2 SUPERCRITICL PRESSURE DROP When pressure ratio is supercritical, speed of flow reaches acoustic velocity at the narrowest section causing higher level of noisiness, cavitation or flashing, the single or double perforated trim design is recommended. INHERENT FLOW CHRCTERISTICS Kv Kv 0 H PT PL On-off, the flow rate changes from 0 to 100% - fully open or fully closed control. Linear, the flow capacity or Kv increases linearly with valve travel. The flow is directely proportional to the valve travel.recommended when there are no relevant variations in differential pressure or flow rates EQP Equal-percentage, for equal increments of valve plug travel the change in flow rate with respect to travel may be expressed as a constant percent of the flow rate at the time of the change. t constant differential pressure, the valve travel increase of 10% usually corresponds to a flow rate increase equal to 50% of the valve flow preceding the variation. The change in flow rate observed with respect to travel will be relatively small when the valve plug is near it s seat and relatively high when the valve plug is nearly wide open. Recommended when there are wide variations in flow rate or differential pressure. 438

3 CONTROL VLVES General Information TWO WY VLVES pplication: On/off, control of flow, pressure, temperature. Fig.1 THREE WY MIXING VLVES pplication: Mixing of two streams y-pass at heat exchangers Fig. THREE WY DIVERTING VLVES pplication: Diverting of two streams y-pass at heat exchangers * Diverting into two different systems (* The mixing design is recommended, see Fig.6) Fig.3 439

4 TYPICL REGULTION LOOPS Fig.4 TYPICL REGULTION LOOPS Two-way valve arrangement Fluid : saturated steam Three way mixing valve arrangement (mixing regulation) Fluids: water, diathermic oil, Fig.5 Three way mixing valve arrangement (diverting regulation) Fluids: water, diathermic oil, Fig.6 Three way diverting valve arrangement Fluids: water, diathermic oil, Fig.7 Two-way valve arrangement Fluids: water, diathermic oil, 440

5 Pm (bar) Pa (bar) T ( C) PHYSICL PROPERTIES OF STURTED STEM V (m 3 /Kg) he (Kcal/Kg) he (KJ/Kg) r (Kcal/Kg) r (KJ/Kg) hg (Kcal/Kg) hg (KJ/Kg) 0,00 1, ,0 1, ,1 419,1 539,4 58,4 639,5 677,5 0,05 1, ,4 1, ,5 45,0 538,4 54, 639,9 679,1 0,10 1,113 10,6 1,533 10,8 430,4 537,7 51, 640,5 681,6 0,15 1, ,1 1, ,1 435,8 536,9 47,9 641,0 683,7 0,0 1,13 106, 1, ,3 440,9 536, 45,0 641,5 685,8 0,30 1, ,4 1,31 107,6 450,5 534,7 38,7 64,3 689, 0,40 1, ,5 1,5 109,8 459,7 533,3 3,8 643,1 69,5 0,50 1, ,6 1, ,9 468,5 531,9 7,0 643,8 695,5 0,60 1, ,5 1, ,8 476,5 530,6 1,5 644,4 698,0 0,70 1, ,4 1,04 115,7 484,4 59,5 16,9 645, 701,3 0,80 1, ,1 0, ,5 491,9 58,3 11,9 645,8 703,8 0,90 1, ,8 0,93 119, 499,1 57,1 06,9 646,3 705,9 1,00,013 10,4 0,881 10,8 505,8 56,0 0,3 646,8 708,0 1,10,113 11,9 0,841 1,4 51,5 55,1 198,5 647,5 711,0 1,0,13 13,4 0,806 14,0 519, 54,1 194,3 648,1 713,5 1,30,313 14,9 0,773 15,4 55,0 53,1 190,1 648,5 715,1 1,40,413 16,3 0,743 16,8 530,9 5, 186,3 649,0 717, 1,50,513 17,6 0,714 18,1 536,3 51,1 181,7 649, 718,1 1,60,613 18,9 0,689 19,5 54, 50,4 178,8 649,9 71,0 1,70, ,1 0, ,7 547, 519,5 175,0 650, 7,3 1,80, ,4 0,643 13,0 55,7 518,6 171,3 650,6 73,9 1,90,913 13,5 0,6 133, 557,7 517,8 167,9 651,0 75,6,00 3, ,7 0, ,4 56,7 517,0 164,6 651,4 77,3,0 3,13 135,9 0, ,6 571,9 515,5 158,3 65,1 730,,40 3, ,0 0, ,8 581,1 514,0 15,0 65,8 733,1,60 3, ,0 0, ,8 589,5 51,6 146, 653,4 735,7,80 3, ,9 0,483 14,8 597,9 511, 140,3 654,0 738, 3,00 4, ,7 0, ,7 605,8 509,9 134,8 654,6 740,7 3,0 4,13 145,4 0, ,4 61,9 508,6 19,4 655,0 74,4 3,40 4, , 0,4 148, 60,5 507,4 14,4 655,6 744,9 3,60 4, ,8 0, ,9 67,6 506,1 118,9 656,0 746,5 3,80 4, ,4 0, ,5 634,3 505,0 114,3 656,5 748,6 4,00 5,013 15,0 0, ,1 641,0 503,8 109,3 656,9 750,3 4,0 5,13 153,4 0, ,6 647,3 50,7 104,7 657,3 75,0 4,40 5, ,8 0, ,1 653,6 501,6 100,1 657,7 753,7 4,60 5, , 0, ,6 659,8 500,6 095,9 658, 755,8 4,80 5, ,6 0,35 159,0 665,7 499,5 091,3 658,5 757,0 5,00 6, ,9 0, ,3 671,1 498,5 087,1 658,8 758,3 5,50 6,513 16,1 0,9 163,6 685,0 496,1 077,1 659,7 76,0 6,00 7, ,0 0,7 166,7 697,9 493,8 067,4 660,5 765,4 6,50 7, ,8 0,55 169,6 710,1 491,6 058, 661, 768,3 7,00 8, ,5 0,40 17,4 71,8 489,4 049,0 661,8 770,8 7,50 8, ,0 0,7 175,1 733,1 487,4 040,6 66,5 773,8 8,00 9, ,4 0,15 177,6 743,6 485,4 03,3 663,0 775,8 8,50 9, ,7 0,04 180,0 753,6 483,5 04,3 663,5 777,9 9,00 10, ,0 0,194 18,3 763,3 481,6 016,4 663,9 779,6 9,50 10,513 18,1 0, ,6 77,9 479,8 008,8 664,4 781,7 10,00 11, ,1 0, ,8 78,1 478,0 001,3 664,8 783,4 11,00 1, ,0 0, ,9 799,3 474,6 1987,1 665,5 786,3 1,00 13, ,7 0, ,8 815,6 471,4 1973,7 666, 789, 13,00 14, ,1 0, ,5 831,1 468,3 1960,7 666,8 791,8 14,00 15, ,3 0,13 0,0 845,7 465,3 1948,1 667,3 793,9 15,00 16,013 01,4 0,14 05,3 859,6 46,5 1936,4 667,8 795,9 16,00 17,013 04,4 0,117 08,5 87,9 459,7 194,7 668, 797,6 17,00 18,013 07, 0,110 11,5 885,5 457,0 1913,4 668,5 798,9 18,00 19,013 09,9 0,105 14,4 897,8 454,4 190,5 668,8 800,1 19,00 0,013 1,5 0,100 17, 909,4 451,8 1891,6 669,0 801,0 0,00 1,013 15,0 0,095 0,0 91,1 449,4 1881,5 669,4 80,6 1,00,013 17,3 0,090,6 93,0 447,0 1871,5 669,6 803,5,00 3,013 19,6 0,087 5,1 94,4 444,6 1861,5 669,7 803,9 3,00 4,013 1,8 0,083 7,6 95,9 44, 1851,4 669,8 804,3 4,00 5,013 4,0 0,080 30,0 963,0 440,0 184, 670,0 805, 5,00 6,013 6,1 0,077 3,3 97,6 437,7 183,6 670,0 805, 441

6 Pm bar MSS FLOWRTES OF STURTED STEM FOR DIFFERENT VELOCITIES IN PIPES DIN448 - STNDRD v FLOWRTE Kgs / h m/s DN DN DN DN DN DN DN DN DN DN DN DN DN DN / /