Flow Measurement

1. Flow Measurement Mark Murphy, PE Technical Director, Fluor Corp. ISA = International Society of AutomationISA = International Society of Automation

2. 2# COMMONLY USED FLOW DEVICES Differential Pressure (Head) Type Orifice Plate - Concentric, Eccentric, Segmental, Quadrant Edge, Integral, Conditioning Venturi Tube Flow Nozzles Elbow Pitot Tube, Averaging Pitot Tube (Annubar) Variable Area (Rotameter) Wedge Meter V-Cone Mass Type � measures the mass flow rate directly. Coriolis Thermal Velocity Type Magnetic Ultrasonic - Transit Time, Doppler Turbine Vortex Open Channel Type Weir Parshall Flume Other Types Positive Displacement Target The following is a list of commonly used flow devices in the Oil & Gas Industry. A corporate standard in many cases provides guidance on the evaluation criteria for flowmeter selection. There are many types of flowmeters available and each has its own application and advantages & limitations, but should always follow project specifications first and be aware that information can vary for the same type of flowmeter between different manufacturers. There the Differential Pressure (Head) Type, which is the most common flow measuring system, where flow is inferred from the differential pressure caused by the flow. This type of flow meter is based on Bernoullis Equation. Differential Pressure (Head) Type flowmeters include the following: Orifice Plate - Concentric, Eccentric, Segmental, Quadrant Edge, Integral, Conditioning Venturi Tube Flow Nozzles Elbow Pitot Tube, Averaging Pitot Tube (Annubar) Variable Area (Rotameter) Wedge Meter V-Cone Another type of flowmeter is the Mass Type, which measures the mass flow rate directly. Mass Type flowmeters include the following: Coriolis Thermal Another type of flowmeter is the Velocity Type, where flow is calculated by measuring the speed in one or more points in the flow and integrating the flow speed over the flow area. Velocity Type flowmeters include the following: Magnetic Ultrasonic - Transit Time, Doppler Turbine Vortex Other Types of flowmeters commonly used in the oil and gas industry include: Positive Displacement Target Another type of flowmeter is the Open Channel Type, where the common method of measuring flow through an open channel is to measure the height of the liquid as it passes over an obstruction (flume or weir) in the channel. Open Channel Type flowmeters include the following: Weir Parshall Flume The following is a list of commonly used flow devices in the Oil & Gas Industry. A corporate standard in many cases provides guidance on the evaluation criteria for flowmeter selection. There are many types of flowmeters available and each has its own application and advantages & limitations, but should always follow project specifications first and be aware that information can vary for the same type of flowmeter between different manufacturers. There the Differential Pressure (Head) Type, which is the most common flow measuring system, where flow is inferred from the differential pressure caused by the flow. This type of flow meter is based on Bernoullis Equation. Differential Pressure (Head) Type flowmeters include the following: Orifice Plate - Concentric, Eccentric, Segmental, Quadrant Edge, Integral, Conditioning Venturi Tube Flow Nozzles Elbow Pitot Tube, Averaging Pitot Tube (Annubar) Variable Area (Rotameter) Wedge Meter V-Cone Another type of flowmeter is the Mass Type, which measures the mass flow rate directly. Mass Type flowmeters include the following: Coriolis Thermal Another type of flowmeter is the Velocity Type, where flow is calculated by measuring the speed in one or more points in the flow and integrating the flow speed over the flow area. Velocity Type flowmeters include the following: Magnetic Ultrasonic - Transit Time, Doppler Turbine Vortex Other Types of flowmeters commonly used in the oil and gas industry include: Positive Displacement Target Another type of flowmeter is the Open Channel Type, where the common method of measuring flow through an open channel is to measure the height of the liquid as it passes over an obstruction (flume or weir) in the channel. Open Channel Type flowmeters include the following: Weir Parshall Flume

3. 3# FLOW MEASUREMENT - TERMS DENSITY (r) A Measure Of Mass Per Unit Of Volume (lb/ft3 or kg/M3). SPECIFIC GRAVITY The Ratio Of The Density Of A Material To The Density Of Water Or Air Depending On Whether It Is A Liquid Or A Gas. COMPRESSIBLE FLUID Fluids (Such As Gasses) Where The Volume Changes With Respect To Changes In The Pressure. These Fluids Experience Large Changes In Density Due To Changes In Pressure. NON-COMPRESSIBLE FLUID Fluids (Generally Liquids) Which Resist Changes In Volume As The Pressure Changes. These Fluids Experience Little Change In Density Due To Pressure Changes.

4. 4# FLOW MEASUREMENT - TERMS Linear Transmitter output is directly proportional to the flow input. Square Root Flow is proportional to the square root of the measured value. Beta Ratio (d/D) Ratio of a differential pressure flow device bore (d) divided by internal diameter of pipe (D). A higher Beta ratio means a larger orifice size. A larger orifice plate bore size means greater flow capacity and a lower permanent pressure loss. Pressure Head The Pressure At A Given Point In A Liquid Measured In Terms Of The Vertical Height Of A Column Of The Liquid Needed To Produce The Same Pressure. The following terminology is normally used in flow measurement, including: Rangeability (Turndown), the ratio of maximum flow to minimum flow, but not zero flow. Repeatability, the ability of a flow meter to indicate the same readings each time the same flow conditions exist. These readings may or may not be accurate, but will repeat. This capability is important when a flow meter is used for flow control. Linear, where the transmitter output is directly proportional to the flow input. Square Root, where flow is proportional to the square root of the sensed differential pressure (head). Beta Ratio (d/D), which is the ratio of orifice plate or other differential pressure flow device bore (d) divided by internal diameter of pipe (D). A higher Beta ratio means a larger orifice plate bore size. A larger orifice plate bore size means greater flow capacity and a lower permanent pressure loss.The following terminology is normally used in flow measurement, including: Rangeability (Turndown), the ratio of maximum flow to minimum flow, but not zero flow. Repeatability, the ability of a flow meter to indicate the same readings each time the same flow conditions exist. These readings may or may not be accurate, but will repeat. This capability is important when a flow meter is used for flow control. Linear, where the transmitter output is directly proportional to the flow input. Square Root, where flow is proportional to the square root of the sensed differential pressure (head). Beta Ratio (d/D), which is the ratio of orifice plate or other differential pressure flow device bore (d) divided by internal diameter of pipe (D). A higher Beta ratio means a larger orifice plate bore size. A larger orifice plate bore size means greater flow capacity and a lower permanent pressure loss.

5. 5# FLOW MEASUREMENT - UNITS Flow is measured as a quantity (either volume or mass) per unit time Volumetric units Liquid gpm, bbl/day, m3/hr, liters/min, etc. Gas or Vapor ft3/hr, m3/hr, etc. Mass units (either liquid, gas or vapor) lb/hr, kg/hr, etc. Flow can be measured in accumulated (totalized) total amounts for a time period gallons, liters, meters passed in a day, etc. Flow can be measured as a rate per unit time. For Liquids, the common units used are: gpm, m3/hr, liters/min, etc. For Gas, the common units used are: ft3/hr, etc. Flow can be measured as a mass per unit time. Common units used are: lb/hr, kg/hr, etc. Flow can be measured in accumulated (totalized) total amounts for a time period. Common units used are: gallons, liters, meters passed in a day, etc.Flow can be measured as a rate per unit time. For Liquids, the common units used are: gpm, m3/hr, liters/min, etc. For Gas, the common units used are: ft3/hr, etc. Flow can be measured as a mass per unit time. Common units used are: lb/hr, kg/hr, etc. Flow can be measured in accumulated (totalized) total amounts for a time period. Common units used are: gallons, liters, meters passed in a day, etc.

6. 6# LAMINAR FLOW Laminar Flow - Is Characterized By Concentric Layers Of Fluid Moving In Parallel Down The Length Of A Pipe. The Highest Velocity (Vmax) Is Found In The Center Of The Pipe. The Lowest Velocity (V=0) Is Found Along The Pipe Wall. Laminar Flow - Is Characterized By Concentric Layers Of Fluid Moving In Parallel Down The Length Of A Pipe. The Highest Velocity (Vmax) Is Found In The Center Of The Pipe. The Lowest Velocity (V=0) Is Found Along The Pipe Wall. Laminar Flow - Is Characterized By Concentric Layers Of Fluid Moving In Parallel Down The Length Of A Pipe. The Highest Velocity (Vmax) Is Found In The Center Of The Pipe. The Lowest Velocity (V=0) Is Found Along The Pipe Wall.

7. 7# TURBULENT FLOW Turbulent Flow - Is Characterized By A Fluid Motion That Has Local Velocities And Pressures That Fluctuate Randomly. This Causes The Velocity Of The Fluid In The Pipe To Be More Uniform Across A Cross Section. Turbulent Flow - Is Characterized By A Fluid Motion That Has Local Velocities And Pressures That Fluctuate Randomly. This Causes The Velocity Of The Fluid In The Pipe To Be More Uniform Across A Cross Section. Turbulent Flow - Is Characterized By A Fluid Motion That Has Local Velocities And Pressures That Fluctuate Randomly. This Causes The Velocity Of The Fluid In The Pipe To Be More Uniform Across A Cross Section.

8. 8# REYNOLDS NUMBER The Reynolds number is the ratio of inertial forces (velocity and density that keep the fluid in motion) to viscous forces (frictional forces that slow the fluid down) and is used for determining the dynamic properties of the fluid to allow an equal comparison between different fluids and flows. Laminar Flow occurs at low Reynolds numbers, where viscous forces are dominant, and is characterized by smooth, constant fluid motion Turbulent Flow occurs at high Reynolds numbers and is dominated by inertial forces, producing random eddies, vortices and other flow fluctuations. The Reynolds number is the most important value used in fluid dymanics as it provides a criterion for determining similarity between different fluids, flowrates and piping configurations. The Reynolds number is the ratio of inertial forces (velocity and density that keep the fluid in motion) to viscous forces (frictional forces that slow the fluid down) and is used for determining the dynamic properties of the fluid to allow an equal comparison between different fluids and flows. Laminar Flow occurs at low Reynolds numbers, where viscous forces are dominant, and is characterized by smooth, constant fluid motion Turbulent flow occurs at high Reynolds numbers and is dominated by inertial forces, producing random eddies, vortices and other flow fluctuations. The Reynolds number is the most important dimensionless number in fluid dynamics and provides a criterion for determining similarity between different fluids, flowrates and piping configurations. The Reynolds number is the ratio of inertial forces (velocity and density that keep the fluid in motion) to viscous forces (frictional forces that slow the fluid down) and is used for determining the dynamic properties of the fluid to allow an equal comparison between different fluids and flows. Laminar Flow occurs at low Reynolds numbers, where viscous forces are dominant, and is characterized by smooth, constant fluid motion Turbulent flow occurs at high Reynolds numbers and is dominated by inertial forces, producing random eddies, vortices and other flow fluctuations. The Reynolds number is the most important dimensionless number in fluid dynamics and provides a criterion for determining similarity between different fluids, flowrates and piping configurations.

9. 9# REYNOLDS NUMBER This is the equation for determining the Reynolds number. You can get the required values from process.This is the equation for determining the Reynolds number. You can get the required values from process.

10. 10# IDEAL GAS LAW An Ideal Gas or perfect gas is a hypothetical gas consisting of identical particles with no intermolecular forces. Additionally, the constituent atoms or molecules undergo perfectly elastic collisions with the walls of the container. Real gases act like ideal gases at low pressures and high temperatures. Real Gases do not exhibit these exact properties, although the approximation is often good enough to describe real gases. The properties of real gases are influenced by compressibility and other thermodynamic effects. An ideal gas or perfect gas is a hypothetical gas consisting of identical particles with no intermolecular forces. Additionally, the constituent atoms or molecules undergo perfectly elastic collisions with the walls of the container. Real gases act like ideal gases at low pressures and high temperatures. Real gases do not exhibit these exact properties, although the approximation is often good enough to describe real gases. The properties of real gases are influenced by compressibility and other thermodynamic effects. An ideal gas or perfect gas is a hypothetical gas consisting of identical particles with no intermolecular forces. Additionally, the constituent atoms or molecules undergo perfectly elastic collisions with the walls of the container. Real gases act like ideal gases at low pressures and high temperatures. Real gases do not exhibit these exact properties, although the approximation is often good enough to describe real gases. The properties of real gases are influenced by compressibility and other thermodynamic effects.

11. 11# IDEAL GAS LAW PV = nRT Where: P = Pressure (psia) V = Volume (FT3) n = Number of Moles of Gas (1 mole = 6.02 x 1023 molecules) R = Gas Constant (10.73 FT3 PSIA / lb-mole oR) T = Temperature (oR) This is the equation for an Ideal GasThis is the equation for an Ideal Gas

12. 12# REAL GASES Compressibility Factor (Z) - The term "compressibility" is used to describe the deviance in the thermodynamic properties of a real gas from those expected from an ideal gas. Real Gas Behavior can be calculated as: PV = nZRT Compressibility Factor (Z) - The term "compressibility" is used to describe the deviance in the thermodynamic properties of a real gas from those expected from an ideal gas. This is the equation for an Ideal GasCompressibility Factor (Z) - The term "compressibility" is used to describe the deviance in the thermodynamic properties of a real gas from those expected from an ideal gas. This is the equation for an Ideal Gas

13. 13# STANDARD CONDITIONS P = 14.7 PSIA T = 520 deg R (60 deg F) Behavior of gases in a process can be equally compared by using standard conditions � This is due to the nature of gases. Standard conditions allow gases and vapors of different compositions to be compared equally.Standard conditions allow gases and vapors of different compositions to be compared equally.

14. 14# ACTUAL CONDITIONS Standard conditions can be converted to Actual Conditions using the Ideal Gas Law.