Orifice Calculation - Find Pressure Drop

ISO 5167-2:2003 Orifice Pressure Drop Calculator


Identification Data

Tagname
Site
Area
Notes

Fluid Data

Fluid
State of matter
Density
Kg/m3
Molecular Weight g
Operating Temperature
C
Operating Pressure (P1)
bar
Dynamic Viscosity
cP
Ratio of Sp.Heats N/A

Pipe Data

Pipe Diameter
mm
Orifice Diameter
mm
Mass Flow Kg/s
Pressure Tappings

Common Results

Pressure Ratio (P2/P1) N/A Pressure Drop Ratio (DP/P1) N/A
Reynolds (ReD) N/A Reynolds Flow Regime N/A
Beta Ratio N/A Discharge Coefficient N/A

Specific Results

Pressure Range bar

Limits of Use

1. Orifice Diameter (d) - The result has not yet been evaluated.
2. Pipe Diameter (D) minimum size - The result has not yet been evaluated.
3. Pipe Diameter (D) maximum size - The result has not yet been evaluated.
4. Beta Ratio (Beta) minimum size - The result has not yet been evaluated.
5. Beta Ratio (Beta) maximum size - The result has not yet been evaluated.
6. Reynolds Number (ReD) - The result has not yet been evaluated.
7. Pressure Ratio - The result has not yet been evaluated.

How the Orifice Plate Find Pressure Drop Calculator works?

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All of our calculators work in a similar way. First you will find a block of information called "Identification Data". In this block we ask you to indicate the Tag, the Plant where the instrument is located and the Area. You also have the possibility to add some notes. This information will be attached to the report if you wish to provide it. It is not necessary to perform the calculation.
The next block of information is called "Fluid Data". In this block we ask you to indicate the the name of your fluid, state of matter, and other properties of your fluid. If you select gas, density is calculated based on the Pressure, Molecular Weight and Temperature properties.
The last input block is called "Pipe Data". A set of cells defining pipe data in a restriction orifice calculation includes parameters such as pipe diameter, orifice diameter and flow properties, which are used to evaluate pressure drops, flow rates, and orifice sizing accurately.
Once everything is set you must click on Calculate! button. Then, all the resulting cells will be calculated. You can press this button until your results are inline with your expectations. Once everything is correct you can export your work to PDF document containing all your parameters and results. To be able to obtain this file you must click on Download button.
We hope you enjoy using this calculator.

Information and Definitions

Used Equation
Formula
Dimensional Analysis
Formula
Beta Ratio The ratio of the orifice diameter to the pipe diameter, affecting flow restriction and pressure drop. It is essential in flow measurement, with specific ratios optimizing accuracy for different flow ranges.
Common Results Refers to standard calculations and outputs in fluid mechanics, such as flow rate, pressure drop, and velocity, essential for analyzing system performance and determining if the design meets operational requirements.
Contraction Coefficient A factor representing the reduction in cross-sectional area in a flow contraction, influencing flow speed and pressure. It is used in flow calculations involving orifices and sudden changes in pipe diameter.
Critical P Ratio The critical pressure ratio is the ratio of downstream to upstream pressure at which gas flow becomes choked, meaning maximum flow rate is reached. It is essential in designing nozzles and controlling flow in compressible fluid systems.
Density Density is the mass per unit volume of a fluid, typically measured in kg/m3. It impacts fluid behavior, such as buoyancy and pressure. High-density fluids exert greater pressure in systems, influencing design parameters in piping and fluid transport applications.
Dynamic Viscosity Dynamic viscosity is a measure of a fluid's resistance to shear or flow, measured in Pascal-seconds (Pa s) or centipoise (cP). It affects how easily a fluid flows through pipes and around objects, influencing energy requirements in pumping systems.
Fluid Data Refers to essential information about a fluid, including properties like density, viscosity, and specific heat. This data is crucial for calculating flow rates, pressure drops, and heat transfer in systems. Fluid data helps engineers understand fluid behavior under different conditions, which aids in designing efficient systems in industries like oil, gas, and water treatment.
Limits of Use Defines the operational boundaries, like maximum pressure or temperature, for a system. Staying within these limits ensures safe, efficient operation and protects equipment from damage or failure.
Mass Flow (Kg/h) The amount of fluid mass passing through a point per hour. It is critical for measuring fluid transport, affecting system sizing, energy requirements, and overall efficiency in industrial processes.
Mass Flow (Kg/s) Mass flow in kg/s indicates fluid mass per second, important for real-time flow control and energy calculations in fast-moving fluid systems, especially in high-demand applications like power generation.
Molecular Weight Molecular weight is the mass of a molecule of a substance, measured in atomic mass units (amu). In fluid mechanics, it helps calculate the density of gases and affects the fluid's compressibility and flow characteristics, particularly for gases in dynamic systems.
Operating Pressure The pressure at which a system operates, influencing fluid density and flow rate. Higher pressures increase fluid density in gases, affecting flow calculations and system integrity. Operating pressure is crucial for safety, efficiency, and equipment durability in fluid systems.
Operating Temperature The temperature at which a fluid operates within a system, influencing its viscosity, density, and flow behavior. Higher temperatures generally decrease fluid viscosity, affecting the resistance to flow, and can also impact material compatibility and safety limits.
Orifice Diameter The diameter of an orifice or opening in a pipe, often used in flow measurement. It restricts flow, creating a pressure difference used to calculate flow rate, with smaller diameters increasing pressure drop and reducing flow.
Pipe Data Refers to the dimensions, materials, and specifications of piping systems, affecting fluid dynamics, resistance, and capacity. Pipe data is essential for designing efficient fluid transport systems and calculating parameters like flow rate and pressure drop.
Pipe Diameter Pipe diameter is the internal width of a pipe, influencing flow rate, velocity, and pressure drop. Larger diameters reduce friction and resistance, improving flow efficiency but requiring more space and higher installation costs.
Pressure Drop Pressure drop is the reduction in fluid pressure as it flows through a system, caused by friction, restrictions, or changes in elevation. It is a key factor in energy loss and pump selection in fluid systems.
Pressure Drop Ratio The ratio of pressure drop across an element to the inlet pressure. It helps assess energy losses and efficiency in a system, with high ratios indicating significant pressure loss and potential flow restrictions.
Pressure Ratio The ratio of outlet pressure to inlet pressure, used to describe pressure changes across systems. It is crucial in analyzing compressible flows, particularly in gas systems, to determine flow characteristics and efficiency.
Ratio of Sp.Heats The ratio of specific heats, or heat capacity ratio (kappa), is the ratio of a fluid's specific heat at constant pressure to its specific heat at constant volume. It affects compressible flow and is critical in calculations involving gases and thermodynamics.
Reynolds Flow Regime The classification of flow as laminar, transitional, or turbulent based on the Reynolds number. It affects flow behavior, pressure drop, and efficiency, guiding the design and operation of fluid systems.
Reynolds Number A dimensionless number indicating whether a fluid flow is laminar or turbulent, calculated from fluid velocity, density, viscosity, and characteristic length. It helps predict flow patterns and friction losses in pipes and channels.
Specific Results Refers to calculated values unique to a system's conditions, such as specific flow rates or pressure conditions, essential for verifying that the system operates within desired parameters for performance and safety.
State of Matter Defines the physical state of a substance: solid, liquid, or gas, determined by temperature and pressure. In fluid mechanics, the state of matter affects fluid flow, density, and viscosity. Gases are compressible, liquids nearly incompressible, and each state behaves uniquely under dynamic conditions.
Velocity in Pipe The speed of fluid movement through a pipe, influenced by pipe diameter and flow rate. It affects pressure drop, energy losses, and is crucial for sizing pipes to avoid excessive turbulence or friction.
Volumetric Flow The volume of fluid passing through a point per unit time, often in m3/h. It is used in pump sizing, system efficiency calculations, and to ensure fluid supply meets demand in various processes.

Orifice Plate Find Size Calculator References

1 International Organization of Standards (ISO 5167-1). 2003. Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full - Part 1: General principles and requirements.
2 International Organization of Standards (ISO 5167-2) 2003. Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full -- Part 2: Orifice plates.
3 American Society of Mechanical Engineers (ASME). 2001. Measurement of fluid flow using small bore precision orifice meters. ASME MFC-14M-2001.
4 U.S. Dept. of the Interior, Bureau of Reclamation, 2001 revised, 1997 third edition, Water Measurement Manual.
5 Michael Reader-Harris (2015) Orifice Plates and Venturi Tubes.
6 Miller, R. W., Flow Measurement Handbook, 3rd ed., McGraw-Hill, New York, 1996.
7 American Gas Association, AGA Gas Measurement Manual, American Gas Association, New York.
8 Wikipedia
9 Corrosionpedia
10 Orifice Plates and Venturi Tubes (2015) - Michael Reader-Harris
11 EMERSON Fundamentals of Orifice Meter Measurement
12 Search Data Center

Another calculators or articles that may interest you ...

1 In Flow Rate Calculator you can calculate the volumetric flow rate of any liquid or gas through a specific pipe diameter and download results.
2 Pressure Measurement, a comprehensive guide to pressure measurement principles and techniques.
3 Orifice Plate Calculator-Find Orifice Size is an useful tool to calculate the size of an orifice plate.
4 Density of Common Liquids Table, an easy reference table for liquid density data.
5 Absolute Viscosity of Common Gases, is a table that represents the absolute viscosity of some common fluids and his evolution against the temperature.
6 This is a table of specific heats' ratio for common gases: Heat Capacity Ratio of Common Fluids
7 Molecular Weight Common Fluids Table, an easy reference table for molecular weight data.

Frequently Asked Questions

Q1 What causes pressure drop across an orifice plate?
A1 Pressure drop across an orifice plate occurs due to the restriction in flow area, which accelerates the fluid and decreases its pressure. When fluid passes through the narrow opening, velocity increases, and pressure decreases per the Bernoulli principle. Some energy is lost as heat and turbulence. The pressure partially recovers downstream, but due to irreversible losses, the total pressure remains lower than before the orifice plate. The extent of the pressure drop depends on factors like orifice diameter, fluid properties, and flow velocity.
Q2 How does differential pressure relate to flow rate in an orifice plate?
A2 The differential pressure across an orifice plate is proportional to the square of the flow rate. This relationship is described by the orifice flow equation, which is derived from the Bernoulli equation and the continuity principle. As flow rate increases, differential pressure rises exponentially. By measuring this pressure drop, the volumetric or mass flow rate can be determined using empirical discharge coefficients that account for fluid dynamics. However, flow conditions such as turbulence, viscosity, and Reynolds number influence the accuracy of this measurement.
Q3 How does fluid density affect pressure drop in an orifice plate?
A3 Fluid density plays a significant role in determining the pressure drop across an orifice plate. Since pressure drop is influenced by the velocity of the fluid, a denser fluid results in a different velocity profile compared to a less dense one. The orifice flow equation incorporates density as a factor, meaning that changes in density directly impact the differential pressure reading. For compressible fluids, density varies with pressure and temperature, requiring corrections in flow calculations to ensure accurate measurement. In contrast, incompressible fluids maintain a more consistent density.
Q4 How does pipe roughness influence pressure drop across an orifice plate?
A4 Pipe roughness affects pressure drop across an orifice plate by influencing flow turbulence and boundary layer behavior. A rougher pipe surface increases frictional losses, leading to additional pressure drop beyond what is caused by the orifice itself. If the upstream conditions are not well-controlled, excessive roughness can disrupt the expected velocity profile, causing inaccuracies in differential pressure measurements. Standard flow measurement installations recommend using smooth, straight pipe sections before and after the orifice plate to minimize these effects and maintain accurate flow readings.
Q5 How does pressure recovery occur after an orifice plate?
A5 Pressure recovery after an orifice plate happens as the fluid expands and slows down downstream of the restriction. When fluid passes through the orifice, it accelerates and experiences a pressure drop. As it moves beyond the orifice into a wider pipe section, velocity decreases, and some of the lost pressure is regained. However, due to energy dissipation in turbulence and friction, full pressure recovery does not occur. The degree of recovery depends on factors such as orifice design, flow velocity, and fluid properties, with sharper-edged plates causing greater permanent losses.
Q6 How does temperature affect pressure drop across an orifice plate?
A6 Temperature changes influence pressure drop across an orifice plate by altering fluid properties such as density and viscosity. For gases, higher temperatures reduce density, leading to lower pressure drops for the same volumetric flow rate. Conversely, lower temperatures increase density and result in higher pressure drops. For liquids, viscosity changes with temperature, affecting flow characteristics and frictional losses. Accurate flow measurement requires compensation for temperature variations, particularly in gas applications where density changes significantly with temperature and pressure fluctuations.
Q7 How is cavitation related to pressure drop in an orifice plate?
A7 Cavitation occurs when the local pressure of a fluid drops below its vapor pressure, causing vapor bubbles to form and collapse. In an orifice plate, significant pressure drop at the vena contracta can lead to cavitation if the downstream pressure is insufficient to prevent vaporization. When cavitation occurs, it generates noise, vibration, and potential damage to the orifice plate and piping. To avoid cavitation, the system pressure should be maintained above the fluid vapor pressure, and appropriate orifice plate selection should consider cavitation-prone conditions.
Q8 How is energy lost due to pressure drop in an orifice plate?
A8 Energy loss in an orifice plate results from conversion of pressure energy into kinetic energy and dissipation through turbulence and friction. When fluid accelerates through the orifice, some energy is irreversibly lost as heat and eddies. While pressure partially recovers downstream, the overall system pressure remains lower due to these energy losses. The extent of energy dissipation depends on factors like orifice plate geometry, fluid properties, and flow rate. Managing energy losses is important in high-efficiency flow systems where minimizing pressure drop can reduce pumping or compression costs.
Q9 What is the effect of fluid compressibility on pressure drop in an orifice plate?
A9 Fluid compressibility significantly influences pressure drop across an orifice plate, especially in gases and high-velocity flow conditions. Unlike incompressible fluids, gases undergo density changes as pressure drops. At higher velocities, compressibility effects become pronounced, requiring flow equations that account for variations in density. Correction factors, such as the expansion factor, adjust for these effects to ensure accurate flow measurements. For highly compressible fluids, additional considerations like choked flow conditions must be evaluated to prevent measurement errors and operational issues.
Q10 What is the significance of pressure drop in orifice plate applications?
A10 Pressure drop across an orifice plate is a crucial factor in flow measurement, pump selection, and energy efficiency. While it provides the basis for calculating flow rate using differential pressure, excessive pressure drop can lead to energy losses and increased operational costs. In some applications, managing pressure drop is critical to maintaining system performance and preventing issues such as cavitation or inadequate downstream pressure. Engineers must balance accurate flow measurement with minimal pressure losses by selecting appropriate orifice plate designs and optimizing piping configurations.