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CALCULATOR MODULE : Piping Fitting Minor Loss Factor   ±

Calculate pipe fitting minor loss factors.

Minor loss factors can be defined as:

  • Av (SI) flow coefficient - the flow in cubic meters per second fluid density 1 kilogram per cubic meter which gives a pressure drop of 1 Pa
  • Cv-uk (UK) flow coefficient - the flow in UK gallons per minute of water at 60 degrees F which gives a pressure drop of 1 psi
  • Cv-us (US) flow coefficient - the flow in US gallons per minute of water at 60 degrees F which gives a pressure drop of 1 psi
  • Cv-met (Metric) flow coefficient - the flow in liters per minute of water at 16 degrees C which gives a pressure drop of 1 bar
  • Kv (EU) flow coefficient - the flow in cubic meters per hour of water at 16 degrees C which gives a pressure drop of 1 bar
  • Cv* the dimensionless US flow factor = Cv-us / din^2 (din is the inside diameter in inches)
  • K factor - the ratio of pressure loss over the dynamic pressure
  • Cd or discharge coefficient - the ratio of the actual flow rate of the fluid through the fitting over the frictionless flow rate.

The K factor and discharge coefficient are dimensionless and can be used with any consistent set of units. The dimensionless flow coefficient has inconsistent units, and is unit specific. The flow coefficient Av, Cv-us, Cv-uk, Cv-met and Kv have dimensions length squared, and can not be used interchangeably between different systems of units.

Note : The friction factor K, discharge coefficient Cd, dimensionless flow coefficient Cv*, and flow coefficients Av, Cv-uk, Cv-us, Cv-met and Kv are used in different situations. The discharge coefficient is usually used for discharge through an orifice, but can also be used in other situations (for example pressure relief valves). The flow coefficients Av, Cv-uk, Cv-us, Cv-met and Kv, and the dimensionless flow coefficient Cv* are usually used for valves, but can also be used for other fittings. Engineering judgement is required to determine the correct minor loss factor to use.

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CALCULATOR MODULE : Parallel And Series Piping Fitting   ±

Calculate minor loss factors for parallel and series pipe fittings.

The effective K factor for fittings in series equals the sum of the K factors.

`Ke = ΣKi `

For fittings in parallel the inverse effective K factor equals the sum of the inverse K factors.

`1/(Ke) = Σ1/(Ki) `

The calculators can be used for parallel and series K factor, discharge coefficient Cd, dimensionless flow coefficient Cv*, and flow coefficients Av, Cv-uk, Cv-us, Cv-met and Kv.

Minor loss factors are calculated for:

  • Av (SI) flow coefficient - the flow in cubic meters per second fluid density 1 kilogram per cubic meter which gives a pressure drop of 1 Pa
  • Cv-uk (UK) flow coefficient - the flow in UK gallons per minute of water at 60 degrees F which gives a pressure drop of 1 psi
  • Cv-us (US) flow coefficient - the flow in US gallons per minute of water at 60 degrees F which gives a pressure drop of 1 psi
  • Cv-met (Metric) flow coefficient - the flow in liters per minute of water at 16 degrees C which gives a pressure drop of 1 bar
  • Kv (EU) flow coefficient - the flow in cubic meters per hour of water at 16 degrees C which gives a pressure drop of 1 bar
  • Cv* the dimensionless US flow factor = Cv-us / din^2 (din is the inside diameter in inches)
  • K factor - the ratio of pressure loss over the dynamic pressure
  • Cd or discharge coefficient - the ratio of the actual flow rate of the fluid through the fitting over the frictionless flow rate.

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CALCULATOR MODULE : Piping Fitting Pressure Loss   ±

Calculate outlet pressure and pressure loss through piping and fittings.

The pressure loss is calculated from the Moody diagram using the Darcy-Weisbach friction factor. The Darcy friction factor can be calculated using either the Hagen-Poiseuille laminar flow equation, the original Colebrook White turbulent flow equation, or the modified Colebrook White equation. Changes in elevation are ignored.

For liquid piping with fittings the outlet pressure is calculated by:

`Po = P - 8 (fL/D+ΣK) ρ (Q^2) / (pi^2D^4) `
`ΔP = P - Po `

where :

ΔP = pressure loss
P =inlet pressure
Po = outlet pressure
Po = outlet pressure
ρ = fluid density
Q= fluid volume flowrate
f = Darcy friction factor
L = pipe length
D = pipe inside diameter
Σ K = total fitting K factor

For gas piping with fittings the outlet pressure is calculated by:

`Po = √(P^2 - 16m^2(fd.L / D + ΣK) (mma.SG.ZRoT)/(pi^2D^4) ) `

where :

m = gas mole flowrate
mma = air molar mass
SG = gas specific gravity
Z = gas compressibility factor
Ro = universal gas constant
T = gas temperature

For liquid fittings the outlet pressure is calculated by:

`Po = P - 8 K ρ (Q^2) / (pi^2D^4) `

where :

K = fitting K factor

For gas fittings the outlet pressure is calculated by:

`Po = √(P^2 - m^2K (16mma.SG.ZRoT)/(pi^2D^4) ) `

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CALCULATOR MODULE : Piping Fitting Fluid Property   ±

Calculate pipe fitting gas and liquid density and viscosity.

Calculate liquid density, specific gravity, degrees Baume, degrees Twaddell, or degrees API. For liquids lighter than or equal to water the density can be defined as degrees API, or degrees Baume (Be-). For liquids heavier than water the density can be defined by degrees Baume (Be+), or degrees Twaddell.

Calculate gas density, viscosity and compressibility factor for: methane CH4, ethane C2H6, propane C3H8, iso-butane C4H10, n-butane C4H10, iso-pentane C5H12, n-pentane C5H12, n-hEAne C6H14, n-heptane C7H16, n-octane C8H18, n-nonane C9H20, n-decane C10H22, air N2 + O2, ammonia NH3, argon Ar, carbon dioxide CO2, carbon monoxide CO, chlorine Cl2, helium He, hydrogen H2, hydrogen chloride HCl, hydrogen sulphide H2S, nitrogen N2, oxygen O2, and steam H2O. The gas compressibility factor is calculated from the critical point temperature, critical point temperature, and the accentric factor using either the Peng Robinson, Soave, Redlich Kwong or Van Der Waals equations of state (EOS).

Steam table properties can be calculated for water, saturated water, saturated steam, saturated water and steam, metastable water, and metastable steam.

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CALCULATOR MODULE : Piping Reducer And Enlarger Minor Loss Factor   ±

Calculate typical pipe reducer and enlarger minor loss factors.

The minor loss factors can be calculated for either the small diameter, and the large diameter. The nozzle can be either tapered with a transition, or abrupt with no transition. The taper angle is equal to half the cone angle.

Note : The calculated values are typical. Manufacturers data should be used if it is available.

Minor loss factors are calculated for:

  • Av (SI) flow coefficient - the flow in cubic meters per second fluid density 1 kilogram per cubic meter which gives a pressure drop of 1 Pa
  • Cv-uk (UK) flow coefficient - the flow in UK gallons per minute of water at 60 degrees F which gives a pressure drop of 1 psi
  • Cv-us (US) flow coefficient - the flow in US gallons per minute of water at 60 degrees F which gives a pressure drop of 1 psi
  • Cv-met (Metric) flow coefficient - the flow in liters per minute of water at 16 degrees C which gives a pressure drop of 1 bar
  • Kv (EU) flow coefficient - the flow in cubic meters per hour of water at 16 degrees C which gives a pressure drop of 1 bar
  • Cv* the dimensionless US flow factor = Cv-us / din^2 (din is the inside diameter in inches)
  • K factor - the ratio of pressure loss over the dynamic pressure
  • Cd or discharge coefficient - the ratio of the actual flow rate of the fluid through the fitting over the frictionless flow rate.

Reference : Crane Technical Paper 410M Metric Version : Flow Of Fluids Through Valves, Fittings And Pipe

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CALCULATOR MODULE : Piping Bend And Elbow Minor Loss Factor   ±

Calculate typical pipe bend and elbow minor loss factors (K, Cd, Cv*, Av, Cv-uk, Cv-us, Cv-met and Kv).

Minor loss factors can be calculated for miter bends (single miter and multiple miter), formed bends, close return bends, and standard elbows.

Minor loss factors are calculated for:

  • Av (SI) flow coefficient - the flow in cubic meters per second fluid density 1 kilogram per cubic meter which gives a pressure drop of 1 Pa
  • Cv-uk (UK) flow coefficient - the flow in UK gallons per minute of water at 60 degrees F which gives a pressure drop of 1 psi
  • Cv-us (US) flow coefficient - the flow in US gallons per minute of water at 60 degrees F which gives a pressure drop of 1 psi
  • Cv-met (Metric) flow coefficient - the flow in liters per minute of water at 16 degrees C which gives a pressure drop of 1 bar
  • Kv (EU) flow coefficient - the flow in cubic meters per hour of water at 16 degrees C which gives a pressure drop of 1 bar
  • Cv* the dimensionless US flow factor = Cv-us / din^2 (din is the inside diameter in inches)
  • K factor - the ratio of pressure loss over the dynamic pressure
  • Cd or discharge coefficient - the ratio of the actual flow rate of the fluid through the fitting over the frictionless flow rate.

The calculated values are typical. Manufacturers data should be used if it is available.

Reference : Crane Technical Paper 410M Metric Version : Flow Of Fluids Through Valves, Fittings And Pipe

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CALCULATOR MODULE : Piping Valve Minor Loss Factor   ±

Calculate typical pipe valve minor loss factors (K, Cd, Cv*, Av, Cv-uk, Cv-us, Cv-met and Kv).

The valves are assumed to be fully open. For full port valves the valve port cross section area equals the nominal internal cross section area. For reduced port valves the valve port cross section area is less than the nominal internal cross section area. For circular valve ports the diameter ratio is equal to the valve port diameter over the nominal inside diameter. For non circular valve ports, use the square root of the internal area ratio (the square root of the valve port area over the nominal internal area).

Minor loss factors are calculated for:

  • Av (SI) flow coefficient - the flow in cubic meters per second fluid density 1 kilogram per cubic meter which gives a pressure drop of 1 Pa
  • Cv-uk (UK) flow coefficient - the flow in UK gallons per minute of water at 60 degrees F which gives a pressure drop of 1 psi
  • Cv-us (US) flow coefficient - the flow in US gallons per minute of water at 60 degrees F which gives a pressure drop of 1 psi
  • Cv-met (Metric) flow coefficient - the flow in liters per minute of water at 16 degrees C which gives a pressure drop of 1 bar
  • Kv (EU) flow coefficient - the flow in cubic meters per hour of water at 16 degrees C which gives a pressure drop of 1 bar
  • Cv* the dimensionless US flow factor = Cv-us / din^2 (din is the inside diameter in inches)
  • K factor - the ratio of pressure loss over the dynamic pressure
  • Cd or discharge coefficient - the ratio of the actual flow rate of the fluid through the fitting over the frictionless flow rate.

The calculated values are typical. Manufacturers data should be used if it is available.

Reference : Crane Technical Paper 410M Metric Version : Flow Of Fluids Through Valves, Fittings And Pipe

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CALCULATOR MODULE : Piping Check Valve Minor Loss Factor   ±

Calculate typical gas and liquid pipe check valve minimum velocity and minor loss factors (K, Cd, Cv*, Av, Cv-uk, Cv-us, Cv-met and Kv).

The minimum flowrate is the flowrate required to keep the check valve fully open. For full port valves the valve port cross section area equals the nominal internal cross section area. For reduced port valves the valve port cross section area is less than the nominal internal cross section area. For circular valve ports the diameter ratio is equal to the valve port diameter over the nominal inside diameter. For non circular valve ports, use the square root of the internal area ratio (the square root of the valve port area over the nominal internal area).

Minor loss factors are calculated for:

  • Av (SI) flow coefficient - the flow in cubic meters per second fluid density 1 kilogram per cubic meter which gives a pressure drop of 1 Pa
  • Cv-uk (UK) flow coefficient - the flow in UK gallons per minute of water at 60 degrees F which gives a pressure drop of 1 psi
  • Cv-us (US) flow coefficient - the flow in US gallons per minute of water at 60 degrees F which gives a pressure drop of 1 psi
  • Cv-met (Metric) flow coefficient - the flow in liters per minute of water at 16 degrees C which gives a pressure drop of 1 bar
  • Kv (EU) flow coefficient - the flow in cubic meters per hour of water at 16 degrees C which gives a pressure drop of 1 bar
  • Cv* the dimensionless US flow factor = Cv-us / din^2 (din is the inside diameter in inches)
  • K factor - the ratio of pressure loss over the dynamic pressure
  • Cd or discharge coefficient - the ratio of the actual flow rate of the fluid through the fitting over the frictionless flow rate.

The calculated values are typical. Manufacturers data should be used if it is available.

Reference : Crane Technical Paper 410M Metric Version : Flow Of Fluids Through Valves, Fittings And Pipe

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CALCULATOR MODULE : Piping Control Valve Sizing   ±

Calculate typical gas and liquid pipe control valve sizing and minor loss factors (K, Cd, Cv*, Av, Cv-uk, Cv-us, Cv-met and Kv).

The control valve sizing is calculated in two steps using the ISA-75.01.01 iteration method for Kv flow coefficient. The other flow factors (Av, Cv-uk, Cv-us, Cv-met, Cv*, K, and Cd) are calculated from Kv.

Step 1 : Calculate the required valve flow coefficient (Av, Cv-uk, Cv-us, Cv-met and Kv) assuming that the valve ID is equal to the pipe ID. Use the required flow coefficient to select a suitable valve.

Step 2 : Select a suitable valve size, type and flow coefficient based on manufacturers data. If a full bore valve is too large, a smaller valve should be selected, with assumed concentric reducers. Calculate the required flow coefficient for the selected valve. The required flow coefficient should be less than or equal to the valve flow coefficient. A trial and error process may be required to determine the appropriate valve. It is recommended that the valve diameter is not less than half the pipe diameter. The calculation is not valid if the valve diameter is greater than the pipe diameter. The calculation might not converge if the valve size is too small.

For viscous fluids or very low flow velocity flow, with low Reynolds number (Rev < 10,000) use the Reynolds number factor option. For most flow cases the Reynolds number can be ignored (Fr = 1).

Check for choked conditions. If the outlet pressure for step 1 or step 2 is greater than the minimum (choked) outlet pressure, set the outlet pressure equal to the choked outlet pressure. The maximum (choked) flowrate, maximum (choked) delta pressure and minimum (choked) outlet pressure are calculated from the fluid vapour pressure, and the fluid critical point pressure. Specially designed valves are required to operate at choked conditions.

The K factors should include fittings located with 2D upstream and 6D downstream. The fluid velocity is calculated from the valve ID. The piping is assumed to be constant diameter upstream and downstream of the valve. The liquid pressure recovery factor Fl, and the valve design factor Fd depend on the valve type and geometry. Typical values are included in the data tables. Manufacturers data should be used if it is available. Check that the convergence is close to or equal to one. Convergence problems can indicate that the selected valve size is too small.

The dimensionless flow coefficient Cv* equals Cv-us / IDin^2, where IDin is the valve inside diameter in inches. For control valves, a maximum Cv* value of 30 is recommended, equivalent to a minimum K factor of 1.

Minor loss factors are calculated for:

  • Av (SI) flow coefficient - the flow in cubic meters per second fluid density 1 kilogram per cubic meter which gives a pressure drop of 1 Pa
  • Cv-uk (UK) flow coefficient - the flow in UK gallons per minute of water at 60 degrees F which gives a pressure drop of 1 psi
  • Cv-us (US) flow coefficient - the flow in US gallons per minute of water at 60 degrees F which gives a pressure drop of 1 psi
  • Cv-met (Metric) flow coefficient - the flow in liters per minute of water at 16 degrees C which gives a pressure drop of 1 bar
  • Kv (EU) flow coefficient - the flow in cubic meters per hour of water at 16 degrees C which gives a pressure drop of 1 bar
  • Cv* the dimensionless US flow factor = Cv-us / din^2 (din is the inside diameter in inches)
  • K factor - the ratio of pressure loss over the dynamic pressure
  • Cd or discharge coefficient - the ratio of the actual flow rate of the fluid through the fitting over the frictionless flow rate.

Reference : ISA-75.01.01 Industrial Process Control Valves Part 2-1 Flow Capacity Sizing Equations For Fluid Flow Under Installed Conditions

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CALCULATOR MODULE : Compressible Flow Area And Internal Diameter   ±

Calculate compressible flow cross section area and diameter.

Pipe inside diameter and internal cross section area are calculated from the pipe diameter and wall thickness. Use the Result Table option to display a table of the inside diameter and cross section area versus either outside diameter or wall thickness.

Effective nozzle orifice diameter and cross section area for pressure relief valves is calculated from API letter designation (API 526 type D to T). The combination of valve and nozzle must be tested with the operating fluid, and certified as having a flow rate greater than or equal to the calculated flow rate for the effective size. Use the Result Table option to display the effective diameter and cross section area versus API letter designation.

Reference : Fluid Mechanics, Frank M White, McGraw Hill

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CALCULATOR MODULE : Compressible Flow Pressure Relief Valve   ±

Calculate compressible flow pressure relief valve capacity for isentropic, isothermal, and adiabatic conditions.

For pressure relief valves with no header, the mass flow rate can be calculated for isentropic or isothermal flow. The pressure relief valve is assumed to exit directly to ambient pressure. If the ambient pressure is less than the critical pressure the flow is critical (Mc = 1 for isentropic flow and Mc = √(1/γ) for isothermal flow). If the ambient pressure is greater than the critical nozzle pressure, the flow is sub critical (M < Mc). For isothermal flow the stagnation temperature should be close to or equal to the ambient temperature (for example a gas transmission pipeline). Phase changes are ignored.

For a combined pressure relief valve and pressure relief header, the mass flow rate can be calculated for

  • Isentropic nozzle and adiabatic header
  • Isentropic nozzle and isothermal header
  • Isothermal nozzle and isothermal header

The pressure relief valve is assumed to exit directly into the header. If the header inlet pressure is less than or equal to the nozzle critical pressure the nozzle flow is critical (Mc = 1 for isentropic flow and Mc = √(1/γ) for isothermal flow), and the mass flow rate is restricted by the nozzle. The header inlet pressure is calculated so that the header mass flow rate equals the nozzle mass flow rate. If the header inlet pressure is greater than the critical nozzle pressure, the nozzle flow is sub critical (M < Mc), and the mass flow rate is restricted by the header. The mass flow rate is calculated so that the header inlet pressure is equal to the nozzle pressure. The mass flow rate through the nozzle is always equal to the mass flow rate through the header.

For a pressure relief header, the mass flow rate can be calculated for adiabatic or isothermal flow. If the header is attached directly to the outlet of a pressure relief valve (PRV), the header inlet pressure should be set equal to the PRV nozzle outlet pressure. The header should be sized so that the calculated header mass flowrate is greater than or equal to the PRV mass flowrate. For headers with more than one PRV, the header mass flowrate is divided by the number of PRV's. If the header is oversized, the header inlet pressure will reduce so that the actual header mass flowrate is equal to the nozzle mass flowrate (there is a pressure drop between the PRV outlet and the header inlet).

Note : If the PRV is attached to a small diameter header which feeds into a larger diameter header (possibly with multiple PRVs), the large diameter header should be sized first. The inlet pressure for the large diameter header is used as the ambient pressure for the smaller diameter header (and PRV).

Header pressure losses are calculated from the pressure loss factor (fld = fL/D + K). The Darcy friction factor f is calculated for fully turbulent flow using the rough pipe equation. The header is assumed to be constant diameter. Minor losses can be included by the minor loss K factor, and should include valves and bends etc. The header entry and exit losses should not be included (the fluid dynamic pressure loss is included in the calculation). The discharge coefficient can also be used for minor losses, and as a safety factor. If the ambient pressure is less than the critical header pressure the header exit flow is critical (Mc = 1 for isentropic flow and Mc = √(1/γ) for isothermal flow). If the ambient pressure is greater than the critical header pressure, the header exit flow is sub critical (M < Mc). The header entry flow is assumed to be sub critical for all flow conditions.

The effective PRV valve nozzle orifice diameter and cross section area can be calculated from API letter designation (API 526 type D to T). API effective orifice sizing is used to compensate for the friction pressure losses in the relief valve. The combination of valve and nozzle orifice must be tested with the operating fluid at the design conditions, and certified as having a flow rate greater than or equal to the calculated flow rate for the equivalent size. The API 526 orifice sizing assumes isentropic flow. For certified API 526 valves, the isentropic nozzle calculation option should be used.

Note : The pressure relief header calculation is not suitable for pressure relief vents. Headers are assumed to be part of a PRV system. Vents are constant diameter piping attached to a pipeline or pressure vessel.

Use the Result Plot option to plot pressure, mach number and mass flow rate.

Reference : Fluid Mechanics, Frank M White, McGraw Hill

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CALCULATOR MODULE : Compressible Flow Nozzle Flow Rate   ±

Calculate compressible flow mass flow rate and mole flow rate through a nozzle for isentropic and isothermal flow.

At high pressure the nozzle flow is critical (the critical exit pressure is ≥ the ambient pressure). The critical Mach number Mc = 1 for adiabatic low and Mc = 1 / √γ for isothermal flow (γ = the gas specific heat ratio). At lower pressures the nozzle flow is sub critical (M < Mc) (the critical exit pressure is < the ambient pressure). For isothermal flow the stagnation temperature should be close to or equal to the ambient temperature (eg gas transmission pipeline). The discharge coefficient can be used to account for friction losses, and as a design factor.

Reference : Fluid Mechanics, Frank M White, McGraw Hill

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CALCULATOR MODULE : DNVGL RP O501 Pipeline Bend Erosion Rate   ±
CALCULATOR MODULE : DNVGL RP O501 Pipeline Reducer Erosion Rate   ±
CALCULATOR MODULE : API 520 Pressure Relief Device   ±
CALCULATOR MODULE : API 520 Gas Pressure Relief Valve   ±

Calculate API 520 gas pressure relief valve (PRV) and rupture disk size.

The flow through the relief valve nozzle is assumed to be sonic (M = 1), adiabatic, and isentropic. If the back pressure is greater than the critical (sonic) pressure the flow is subsonic (M < 1).

Friction losses are accounted for using the discharge coefficient Kd. For initial sizing of PRV's the effective nozzle diameter should be used with the discharge coefficient Kd = 0.975. The actual nozzle diameter and the rated coefficient of discharge should be used to verify that the selected PRV is suitable for the required flow rate. The PRV effective diameter is taken from API 526 (letter designation D to T). Changes in phase are not accounted for.

The calculation can also be used for rupture disks. The rupture disk diameter should be substituted for the nozzle diameter, with a discharge coefficient Kd = 0.62. Rupture disks can also be analysed as part of a relief vent system using the flow resistance method.

Note : The ideal gas calculators use the ideal gas compressible flow equations. The API 520 gas and steam calculations use an approximation of the ideal gas compressible flow equations. Use the ideal gas calculators for a comparison with the API 520 calculators.

Reference : API 520 Sizing, Selection And Installation Of Pressure Relieving Devices (2014)

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CALCULATOR MODULE : API 520 Steam Pressure Relief Valve   ±

Calculate API 520 steam pressure relief valve (PRV) and rupture disk size.

The flow through the relief valve nozzle is analysed using the Napier equation. For temperatures above 1200 F (922 K), the gas PRV calculation should be used. If the back pressure is greater than the critical (sonic) pressure the flow is sub sonic (M < 1).

Friction losses are accounted for using the discharge coefficient Kd. For initial sizing of PRV's the effective nozzle diameter should be used with the discharge coefficient Kd = 0.975. The actual nozzle diameter and rated coefficient of discharge should be used to verify that the selected PRV is suitable for the required flow rate. The PRV effective diameter is taken from API 526 (letter designation D to T). Changes in phase are not accounted for.

The calculation can also be used for rupture disks. The rupture disk diameter should be substituted for the nozzle diameter, with a discharge coefficient Kd = 0.62. Rupture disks can also be analysed as part of a relief vent system using the flow resistance method.

Note : The ideal gas calculators use the ideal gas compressible flow equations. The API 520 gas and steam calculations use an approximation of the ideal gas compressible flow equations. Use the ideal gas calculators for a comparison with the API 520 calculators.

Reference : API 520 Sizing, Selection And Installation Of Pressure Relieving Devices (2014)

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CALCULATOR MODULE : API 520 Liquid Pressure Relief Valve   ±

Calculate API 520 liquid pressure relief valve (PRV) and rupture disk size (certified and non certifed devices).

The flow through the relief valve nozzle is analysed using the Bernoulli equation. Friction losses are accounted for using the discharge coefficient Kd. For initial sizing of PRV's the effective nozzle diameter should be used with the discharge coefficient Kd = 0.65 for certified PRV's and Kd = 0.62 for non certified PRV's. The actual nozzle diameter and rated coefficient of discharge should be used to verify that the selected PRV is suitable for the required flow rate. The PRV effective diameter is taken from API 526 (letter designation D to T). Changes in phase are not accounted for.

The PRV calculation can also be used for rupture disks. The rupture disk diameter should be substituted for the nozzle diameter, with a discharge coefficient Kd = 0.62. Rupture disks can also be analysed as part of a relief vent system using the flow resistance method.

Reference : API 520 Sizing, Selection And Installation Of Pressure Relieving Devices (2014)

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CALCULATOR MODULE : API 520 Effective Nozzle Size   ±
DATA MODULE : Pipe Fitting And Valve ( Open In Popup Workbook )   ±
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