Sizing Pressure Regulators & Control Valves

Sizing Pressure Regulators & Control Valves

( ( Sizing the Pressure Regulators Sizing of regulators is usually made on the basis of Cg valve and KG sizing coefficients. Flow rates at fully open position and various operating conditions are related by the following formulae where: = flow rate in Stm 3 /h Pu = inlet pressure in bar (abs) Pd = outlet pressure in bar (abs). A > When the Cg and KG values of the regulator are known, as well as Pu and Pd, the flow rate can be calculated as follows: A-1 in sub critical conditions: (Pu<2xPd) = KG x Pd x ( Pu - Pd ) A-2 in critical conditions: (Pu 2xPd) = 0.526 x Cg x Pu x sin K 1 x ( Pu - Pu Pd = KG 2 x Pu = 0. 526 x Cg x Pu B > Vice versa, when the values of Pu, Pd and are known,the Cg or KG values, and hence the regulator size, may be calculated using: B-1 in sub-critical conditions: (Pu<2xPd) KG = Pd x ( Pu - Pd ) Cg = 0.526 x Pu x sin ( K1x Pu - Pu Pd B-2 in critical conditions (Pu 2xPd) x KG = 2 Cg = Pu 0,526 x Pu NOTE: The sin val is understood to be DEG. CAPACITY REDUCTION TABLE: REGULATOR INTEGRAL SLAM SHUT INTEGRAL MONITOR INTEGRAL SILENCER APERFLUX 851-5% -5% -5% REFLUX 819-7% -7% -5% REFLUX 819/FO -7% -7% -5% APERVAL REVAL 182 SA -10% SA -10% SB -5% SB -7% -5% -5% -7% -5% DIXI -3% Not applicable Not applicable DIVAL 600 0% Not applicable 0% NORVAL -7% Not applicable Not applicable NORVAL 608-7% Not applicable -10%

The above formulae are applicable to natural gas having a relative density of 0.61 w.r.t. air and a regulator inlet temperature of 15 C. For gases having a different relative density d and temperature tu in C, the value of the flow rate, calculated as above, must be multiplied by a correction factor Fc, as follows: Fc = 175.8 S x ( 273.15 + tu ) Correction factors FC Type of gas Air Propane Butane Nitrogen Oxygen Carbon dioxide Relative density 1.0 1.53 2.0 0.97 1.14 1.52 Fc Factor 0.78 0.63 0.55 0.79 0.73 0.63 Lists the correction factors Fc for anumber of gases at 15 C. CAUTION: in order to get optimal performance, to avoid premature erosion phenomena and to limit noise emissions, it is recommended to check gas speed at the outlet flange does not exceed the values of the graph below. Gas pressure at the outlet flange [m/sec] 260 2 240 230 220 210 190 1 170 160 1 140 0 1 2 3 4 5 6 7 8 9 10 11 Outlet pressure [bar] The gas speed at the outlet flange may be calculated by means of the following formula: V = 345.92 x 2 DN 1 - x 0.002 x Pd 1 + Pd where: V = = DN = Pd = gas speed in m/sec gas flow rate in Stm3/h nominal size of regulator in mm outlet pressure in barg.

Cg and Kg valve coefficient Tables Aperflux 101 2 1682 1768 103 3 4 4414 108 Aperflux 851 4 5 113,9 15 1627 113,9 3790 3979 113,9 5554 5837 113,9 1 11112 11678 113,9 17316 18199 113,9 2 24548 8 113,9 Reflux 819 575 605 2220 2335 4937 5194 00 8416 1 16607 17471 933 27282 2 365 384 Reflux 819/FO 575 605 2220 2335 4937 5194 00 8416 1 16607 17471 933 27282 2 365 384

Dixi AP Dival 160 AP 159 167 99,5 140 147 93,5 Staflux 185 Staflux 187 439 462 1681 1768 3764 3960 130 136 Aperval 101 2 2091 2199 108 3 4796 45 108 4 7176 7546 108 Aperval 584 613 90 1978 2077 101 65 1/2 3530 3706 101 45 4751 101 6719 7055 101

Cg and Kg valve coefficient Tables Reval 182 575 605 2220 2335 65 1/2 3320 4197 4937 5194 00 8416 1 16607 17471 933 27282 2 365 384 Terval 1706 1796 108 65 1/2 2731 2875 104 3906 4112 5490 5775 Terval/R 1667 1755 104 65 1/2 2793 2940 104 4099 4315 106 5660 5954 106 Dixi 540 567 96 40 1/2 983 1034 96 1014 1066 96

Dival 600 269 283 94 Head ø 2 40 1/2 652 685 94 781 821 86 Head ø 2/TR 40 1/2 692 727 95 315 331 97 770 9 97 Dival 700 See the capacity Table Norval 331 348 40 1/2 848 892 1360 1430 65 1/2 2240 2356 3395 3571 5 5365 1 10600 11151 16600 17463 Norval 608 1700 1788 106 30 3681 106

( Cg and Kg valve coefficient Tables Sizing the Control Valve Reflux 919 - Syncroflux - VLM Choise of the valve is usually on the basis of Cg valve and Cg flow rate coefficients.cg coefficient corresponds numerically to the value of air flow in SCF/H in critical conditions with full open valve operating with an upstream pressure of 1 psia at a temperature of 15 C.KG. coefficient corresponds numerically to the value of natural gas flow rate in Stm/h in critical conditions with full open valve operating with an upstream pressure of 2 bar abs at a temperature of 15 C. Flow rates at full open position and various working conditions, are bound by the following formule where: Pu = inlet pressure in bar (abs) Pd = outlet pressure in bar (abs) = flow rate in Stm/H KG, Cv, Cg = valve coefficent 1 > When the Cg and KG values of the control valve are known, as well as Pu and Pd, the flow rate can be calculated as follows: 1.1 > in non critical conditions: = K G (Pu - Pd) Pd = 16,8 x Cv x Pu x sin ( Pu - Pd Pu 1.2 > in critical conditions: Pu - Pd = 0,526 x Cg x Pu x sin ( (valid for Pu < 2 x Pd) Pu KG = x Pu = 16,8 x Cv x Pu = 0,526 x Cg x Pu (valid for Pu 2 x Pd) 2 ( 2 > Vice versa, when the values of Pu, Pd and are known, calculate the values of Cv, Cg or KG with: KG = Pd ( Pu - Pd ) Cv =.16,8xPuxsinx ( Pu - Pd (valid for Pu < 2 x Pd) 2.2 > in critical conditions: x K (valid for Pu 2 x Pd) G = 2 Cv = Cg = Pu 16,8 x Pu 0,526 x Pu A oversizing of 20% on calculated values is raccomanded. Cg formulae give flow rate values more correct while K G formulae give values 5% higher than real ones only in noncritical conditions. In the case of noise limitation level a speed at the outlet flange of 130 m/sec. it is also raccomanded. Above formulae are valid for natural gas with a relative specific gravity of 0,61 compared to air and temperature of 15 C at inlet. For gases with different relative specific gravity (S) and temperature t (in C) ), value of flow rate calculated as above, must be adjusted multiplying by: 175.8 Fc = S x ( 273.15 + tu ) Reflux 919 - Syncroflux - VLM Pu ( Cg = 0,526. xpuxsinx ( Pu - Pd Pu ( Cv flow coefficient 575 605 18 2 2335 69 4937 5194 154 00 8416 2 1 16607 17471 519 933 27282 810 2 365 384 1141

Sizing the Control Valve Deltaflux GAS, VAPOR AND STEAM BIPHASE FLUIDS A. Subcritical conditions (when ΔP < 0.5F 2 P1) A. Subcritical conditions (when ΔP < 0.5F 2 P1) Volume flow rate (gas and vapor) = 290 Cv P Δ (P1+P2) G T Weight flow rate (gas and vapor) = 355 Cv GΔP (P1+P2) T Weight flow rate (saturated steam) W = 13,55 Cv ΔP (P1+P2) Weight flow rate (overheated steam) W = 13,55 Cv ΔP (P1+P2) (1+0,00126Δt) B. Critical conditions (when ΔP 0.5F2 P1) Volume flow rate (gas and vapor) 262 F Cv P1 = G T Constant liquid/gas mixture ratio (liquid containing non condensable gas or liquid containing high title vapor) W = 19,1 Cv ΔP (w1+w2) Variable liquid/vapor mixture ratio (liquid containing low title vapor, less then 0.5) W = 27,1 Cv W = 13,5 F Cv ΔP w1 B. Critical conditions (when ΔP 0.5F 2 P1) Constant liquid/gas mixture ratio (liquid containing non condensable gas or liquid containing high title vapor) P1 (w1+w2) Variable liquid/vapor mixture ratio (liquid containing low title vapor, less then 0.5) Weight flow rate (gas and vapor) W = 321 F Cv P1 G T W = 19,1 F Cv P1 w1 Weight flow rate (saturated steam) W = 11,73 F Cv P1 Weight flow rate (overheated steam) F Cv P1 W = 11,73 (1+0,00126 Δ t) w1 = Xg (Vg1-Vf) + Vf w2 = Xg (Vg2-Vf) + Vf

Cg and Kg valve coefficient Deltaflux LIUIDS A. Subcritical conditions (when ΔP < F 2 ΔPc) Volume flow rate f = Cv ΔP 1.17 Gf Weight flow rate W = 855 Cv GfΔP B. Critical conditions (when ΔP F 2 ΔPc) Volume flow rate f = F Cv ΔPc 1.17 Gf Weight flow rate W = 855 F Cv Gf ΔPc ΔPc = P1-Pc Pv Pc = Pv (0,96-0,28 ) Pk ΔPk = Kc (P1-Pv) Note: For values of ΔP ΔPk the valve works under cavitation conditions. Glossary Cv ΔP ΔPc ΔPk Δt F G Gf Kc Xg P1 P2 = valve flow rate coefficient: US gpm of water with P = 1 psi = valve pressure drop P1-P2: bar = maximum dimensioning differential pressure: bar = cavitation differential pressure: bar = overheating temperature delta t1 - ts: C = valve recovery factor: non dimensional = gas relative density (air=1): non dimensional = liquid relative density at operating temperature (water at 15 C=1) = valve incipient cavitation factor: non dimensional = weight percentage of gas or vapor in the mixture at upstream pressure: % = valve upstream pressure: bar abs = valve downstream pressure: bar abs Pc Pk Pv T t1 ts f W W1 W2 Vf Vg1 Vg2 = vena contracta critical pressure: bar abs = thermodynamic critical point pressure: bar abs = vapor pressure at operating temperature: bar abs = upstream gas absolute temperature (273+ C): K = overheated steam upstream temperature: C = saturated steam temperature at upstream pressure: C = volume flow rate at 15 C and 1.013 bar abs: Sm3/h = volume flow rate: m3/h = weight flow rate: Kg/h = upstream mixture density: kg/m3 = downstream mixture density: kg/m3 = specific volume of liquid: m3/kg = specific volume of gas or vapor at upstream pressure: m3/kg = specific volume of gas or vapor at downstream pressure: m3/kg

Cv coefficient Deltaflux Deltaflux Liquid control application Dn 1 1 1 1 20" 2 Cv coefficient at % opening 82 215 405 10 17 2860 39 00 60 8400 10600 16 Liquid trim Deltaflux Gas control application Dn 1 1 1 1 20" 2 Cv coefficient at % opening 60 1 290 6 12 1975 28 3475 4675 59 70 11 Gas trim Note: To verify the dimensioning and, in detail, for the dimensioning of Deltaflux control valves bigger than 24, always refer to Pietro Fiorentini S.p.A.

Sizing the Slam Shut Valves Calculation of the pressure drop The following formula can be used to calculate pressure losses of the slam shut valve in fully open position: Δp = KG x Pu - (KG2 x Pu 2 ) - 4 2 2 x KG Δp = pressure loss in bar Pu = absolute inlet pressure in bar = flow rate Stm3/h KG = flow coefficient Pressure loss calculated as above is referred to natural gas with specific gravity of 0.61 (air=1) temperature of 15 C at valve inlet, for gases with different specific gravity S and temperatures t C, pressure loss can still be calculated with the above formula, replacing the value of the flow coefficent in the table with: KG1 = KG x S x 175.8 ( 273.15 + t)

SBC 782 510 1970 65 1/2 35 4390 7120 1 147 230 2 326 SCN 549 40 1/2 1116 1788 65 1/2 2603 4086 6122 1 136 21700 HBC 975 7120 1 147 230 2 32470 Dilock 108 0 40 1/2 860 976

Sizing the Safety Relief Valves Calculation of the pressure regulator The flow rate is calculated by the following formulae: M q = (0.9 Kc) (394.9 x C) P1 A = 23.661 Z1 T1 q M q = maximum flow rate to be discharged, in Kg/h = maximum flow rate (Stm3/h) A = minimum area (cm 2 ) (see table) Kc = outflow coefficient P 1 = setting pressure plus a 10% overpressure (bar abs) T 1 = temperature in K of the fluid at the valve inlet during the discarge, reported by user or by designer. 0,9 = safety coefficient M = molecular mass of the fluid in Kg/Kmol (see table) Z1 = compressibiliti factor of the fluid under the P1 conditions to be considered approximately equal to one if the actual values is not known. Cp exponent of equation of the isentropic expansion k= Cv under the P1 and T1 conditions. Cp = specific heat at consistant pressure Cv = specific heat at consistant volume 2 C = coefficient of expansion = C = k ( ) (see table) k+1 k+1 k-1

PVS 782 Calculation area (cm2) Outflow coefficient K 4,71 0,56 20,03 0,56 43,01 0,56 74,66 0,56 1 168,56 0,56 9,59 0,56 Molecular mass and expansion coeff. Relative density Carbon dioxide Hydrogen Methane Natural gas* Nitrogen Oxigen Propane * Medium value Molecular mass M 28,97 44,01 2,02 16,04 18,04 28,02 32,00 44,09 Coefficient of expansion C 0,685 0,668 0,686 0,669 0,669 0,685 0,685 0,635 Capacity table versus pressure Pressure Size 2 barg 10 barg 20 barg 30 barg 40 barg Flow rate (Kg/h) 332 1885 2472 5337 7063 2144 16 15357 22697 30038 4604 17214 32976 48738 640 7991 29881 57242 84603 111964 1 143 67462 129235 198 2781 27788 103894 199028 294161 389295

DA SISTEMARE!!!!!!!! Pietro Fiorentini S.p.A. via E.Fermi 8/10 I-36057 Arcugnano (VI) Italy Tel. +39 0444 968.511 Fax. +39 0444 960.468 The data are not binding. We reserve the right to make eventual changes without prior notice. CT-s 570-E April 11 www.fiorentini.com