Mark Murphy, PE Technical Director, Fluor Corp.

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

Level Instrumentation - Selection Criteria
Vessel Type – Atmospheric or Pressurized Vessel Nozzle Orientation Material to be Measured – Liquid, Interface or Solid Process Conditions - Temperature, Pressure, Density, Viscosity, Conductive, Turbulence, Foam, Vaporization Occur at the Surface, Sour or Corrosive Service Measurement Range Measurement Type – Continuous (Transmitter), Point (Switch), Local (Gauge) Contact or Non-Contact Measurement The bullets on this slide and the next list some of the criteria for determining which level measurement technique is best suited or appropriate for a particular level application. The student must keep these in mind at all times since not all techniques will work for all applications. 2

Level Instrumentation – Categories
Head Meters Based on the Measurement of Hydrostatic (Downward) Force of the Liquid Head Level = Pressure = h*sg Calibration in inches of H2O Height Meters Based on the Identification of the Surface of the Liquid Calibration in inches, feet, % Level measurement techniques can be sorted into two specific categories. One is based on the hydrostatic force of the process pushing down on the measuring device, and the other is used to identify the surface of the process. 3

TYPICAL VESSEL

Level Instrumentation Concepts – Level Equipment
Bridle An Instrument Standpipe Allows for Multiple Instruments to be Connected to the Vessel While the Number of Nozzle Connections on the Vessel Remains Two Allows the Instruments to be Isolated from the Vessel without Removing the Vessel from Service Bridle Connection Ratings and Material Should Match Those of the Vessel Should be Provided with Both Vent and Drain Connections Typical Bridle Pipe Size is 2” or 3” The following four bullets on this slide and the two on the next slide describe what a bridle is and some considerations that need to be taken into account on a bridle design. In particular, the bridle material of construction should match that of the vessel to account for material expansion and contraction at the same rates. 5

Stilling Well An Instrument Standpipe which is Open at the Bottom and is Drilled with Vent Holes along the Length of the Standpipe Flanged on Top of Standpipe where Level Instrument will be Mounted Should Allow for Space between Bottom of Vessel and Stilling Well (Minimum of 6”) to Minimize Plugging Provides Additional Protection for Level Instrumentation Reduces Effects of Process (Turbulence, Foaming) Typical Pipe Size is 2” to 4” The following three bullets on this slide and on the next slide describe what a stilling well is and some considerations that need to be taken into account on a stilling well design. Vent holes are added to the stilling well to allow trapped gas to escape from the stilling well as the liquid level rises and to allow gas to enter the stilling well as the liquid level falls. 6

Seal Pot Metal Container used Either to: To Keep the Seal Fluid in the Reference Legs from Boiling Away in Hot Applications (Steam Drums) Allow Maintenance to Fill the Impulse Lines with Seal Fluid or Act as a Reservoir to Keep the Impulse Lines Full The points on this slide describe what a seal pot is and what a seal pot is used for. 7

Jig Set Mechanical Device Used to Exactly Space Vessel, Bridle or Level Gauge Nozzle Connections when Nozzles are Welded in Place The points on this slide describe what a jig set is and what a jig set is used for. 8

Level Instrumentation Concepts – Measurement Types
Level Gauges Guided Wave Radar Radar Differential Pressure Float / Displacer Ultrasonic Capacitance Nuclear Other Level measurement types are divided into the following nine categories. The categories will be typically broken down into an Operating Philosophy behind the concept, Consideration that must be taken into account and Advantages and Limitation of the level measurement concept. The first concept to be discuss is level gauges. 9

Level Instrumentation Types – Level Gauges
Operating Philosophy To Obtain a Reliable and Inexpensive Indication of Liquid Level in a Vessel Considerations The Visible Length Should Cover the Full Operating Range of Interest Including any Other Level Instrumentation on the Vessel If More than One Gauge is Required, the Gauges Must Overlap Each Other Read bullets and discuss. Visible length is for confirming any level transmitter output signal. Overlap is to guarantee continuous reading of level in vessel. 10

Designs Tubular Flat Glass Transparent Reflex Magnetically Coupled Read bullets and discuss. List of the two types of level gauges. More thorough descriptions will follow on the next slides. 11

Tubular Glass Tube with Option of Graduations Not Popular for Process Applications Typically Used for Calibrating Metering Pumps (Calibration Tubes) Tubular gauges like the one shown here are provided with a sealed tube of glass set between two valves. The glass can be plain or provided with graduations. These types of gauges are not normally provided for process applications because of possibility of breaking the exposed glass. They are often used with metering pumps in order to calibrate them. 12

Flat Glass Gauges are Comprised of: Metal Chamber (1 &2) Gasket (5) Glass (3) Cushion (4) Bolts and Nuts (6 & 7) Gauge Limitations: Very High or Very Low Temperatures Poor Design With Multiple Gauges May Limit Level Visibility Gauge Connection Plugging Glass Becoming Etched or Discolored Flat glass type gauges are provided with one or two glass plates supported in a metal chamber. The picture on this slide shows th different parts that make up the gauge and show how it is assembled. Due to the many limitations of gauge glasses many clients are moving away from using them and opting instead to use magnetic level gauges. These will be discussed later under the float, displacer section of level measurement types. 13

Transparent Flat Glass Gauge Glass Sections on Opposite Sides of the Chamber View the Liquid Level through the Gauge Used on Interface Applications and Dirty or Viscous Liquids Illuminators Can be Used to Diffuse Light Evenly on the Back of the Gauge The transparent style of flat glass level gauge is provided with glass sections on opposite sides of the chamber. In this type the liquid level is viewed by looking through the gauge. This type of gauge is used for interface, viscous or dirty liquid applications. These types of gauges are normally provided with illuminators on the back side of the gauge to diffuse light evenly and allow for ease in reading the level.

Reflex Flat Glass Gauge Single Glass Section with Prisms Cut in the Glass on the Process Side Light Striking the Vapor Phase is Refracted to the Viewer which Appears Silvery White Light Striking the Liquid Phase is Refracted into the Liquid which Appears Black Used on Clean, Clear, Noncorrosive Liquids The reflex style of flat glass gauge is manufactured with a single glass section with prisms cut in the glass on the process side. This causes light striking the vapor phase to be refracted to the viewer which appears silvery white while light striking the liquid phase is refracted into the liquid which appears black thus providing a clear indication of the liquid level. These type of gauges can only be used on on clean, clear, noncorrosive liquids. 15

Accessories Illuminators Can be Used to Diffuse Light Evenly on the Back of the Gauge When Used In Cold Service They Can Be Provided With A Frost Extension The picture on the left show a transparent gauge fitted with an illuminator and the one on the right shows a reflex gauge with a frost extension.

Level Instrumentation Types – Float / Displacer
Magnetic Level Gauge Consists of a Non-Magnetic Chamber, Internal Float with Magnet and Bi-Colored Indicator Wafers On many of our projects, clients are moving away from using level gauges and opting instead to use magnetic level gauges. These gauges utilize a float with magnets which change the position on indicating flags in an indicator tube as the level raises and falls. 17

Considerations The Visible Length Should Cover the Full Operating Range of Interest Including any Other Level Instrumentation on the Vessel If More than One Gauge is Required, the Gauges Must Overlap Each Other Level Chamber Needs to be Installed Vertically Level to Reduce any Possible Friction with the Float Require Jig Set Connections May Require a Magnetic Trap The gauge visible length is for confirming any level transmitter output signal and should therefore be set to the full vessel level range. Magnetic gauges can be made to very long lengths so unlike glass gauges there is seldom a need for multiple gauges. However, if multiple gauges are required they should overlap so that the full range is covered. Since these are a cage type device they will require jig set connections if directly attached to the vessel.. This will ensure proper fit up as well as making sure the gauge is mounted vertically. If the gauge is in water service or there is a possibility of carbon steel flakes in the fluid, the gauge should be provided with a magnetic trap. This will catch any magnetic particles and keep them from fouling the magnetic float. Overlap is to guarantee continuous reading of level in vessel. 18

Advantages Long Visible Lengths Corrosive or Toxic Liquid Applications Adaptable to Variations in Fluid Densities High Pressure or Temperature Applications Limitations Affected by changes in fluid density Coating media may seize moving parts Over Pressuring can Implode Float Long ranges may require additional support Magnetic level gauges can be used for very long visible lengths and with corrosive or toxic fluids. They can be used with a wide variety of different fluid densities but like other displacer based instruments are affected by varying fluid density. In other words, the magnetic level gauge can be used for a large range of different densities for different application. It is not good for a range of densities for a single application. It is preferred over the glass level gauge for corrosive or toxic services since there is no glass to possibly break. While it can be used in a variety of temperatures and pressures over pressure can implode the float. The vendor should be consulted for long ranges especially at elevated temperature as the gauge may require additional support. 19

Level Instrumentation Types – Differential Pressure
Operating Philosophy Measures Hydrostatic Head of Liquid in a Vessel Liquid Height Multiplied by a Density Read bullet and discuss. Most common level measurement approach. 20

Considerations Vessel Shape has no Impact Ease of Installation and Isolation Inexpensive and Most Widely Used Variation in Fluid Density Should be Checked Changes with Temperature and Composition Mounting at the Centerline of Bottom Nozzle or Below Read bullets and discuss. Most maintenance personnel are familiar with this measurement type and feel most comfortable with it. Thus it is also the most widely used in the industry. Where will the d/P meter be located and does the liquid density change or is it constant. 21

Diaphragm Seals Offer More Mounting Flexibility Not Susceptible to Plugging or Freezing Easier to Control than Wet Legs May Induce Temperature Errors Added Response Time with Longer Capillaries Small Spans Can be Difficult to Measure Read bullet and discuss. Diaphragm are a possible option with d/P level measurement to isolate the d/P device from the process but again they can have their limitations. 22

Atmospheric Vessels Only High Pressure Side Connected to Vessel Zero Suppression (If Mounted Below Lower Tap) Closed Vessels with Non-Condensable Gas Both High and Low Pressure Sides Connected to Vessel Low Pressure Side is not Filled (Dry leg) Read bullets and discuss. The student should understand the specific challenges that each of these vessel types provides for a differential pressure installation. 23

Closed Vessels with Condensable or Non-Condensable Gas Both High and Low Pressure Sides Connected to Vessel Both High and Low Pressure Sides are Filled (Wet Leg) Fill Fluid is Typically Glycerin / Glycol Sometime even the Process Zero Elevation (Due to Filled Low Pressure Side) Read bullets and discuss. The student should understand the specific challenges that each of this vessel type provides for a differential pressure installation. 24

Differential Pressure Calculation – Pressurized Vessel With Sealed Legs When connecting a D/P level transmitter to a pressurized vessel the high pressure connection is made to the lower connection and the low pressure side is made to the upper connection. The transmitter zero (4 MA) pressure is the difference between low liquid level head and the sealed leg head, and the span (20 MA) pressure is the zero pressure value plus the span head. Note that for this type of measurement both the zero value and span will be negative numbers. The following examples will clarify this in more detail.

Level Instrumentation Types – Bubbler
When Air Pressure Enters a Dip Pipe with a Pressure Greater Than the Hydrostatic Head of the Process Fluid, the Air will Bubble out the Bottom of the Dip Pipe As the Liquid Level Changes, the Air Pressure in the Dip Pipe also Changes Consists of Pressure Regulator, Rotameter and Pressure Gauge Along with a Stilling Well A bubbler is a specialized type of differential pressure level instrument. It works on the principle that air pressure entering a dip pipe with a pressure greater than the hydrostatic head of the process fluid will cause the air will bubble out the bottom of the dip pipe. This is much like blowing into a straw in a glass full of liquid. As the level changes the hydrostatic head will change. This is measured by the d, p transmitter. The calibration of this meter utilizes the same type of calculation used by a d, p transmitter on a vessel. Bubblers are often used in sumps and other tanks where either the only level connection point is from the top or where the fluid is dirty and might foul some other method. 26

Level Instrumentation Types – Bubbler
A picture and sketch of a d/P bubbler installation. Point out to the student the various pieces of a bubbler installation that are visible in the picture. 27

Operating Philosophy – Displacer When a Body is Immersed in a Fluid it Loses Weight Equal to That of the Fluid Displaced – Archimedes Law By Detection of the Apparent Weight of the Immersed Displacer, a Level Measurement can be Inferred Displacers are a level measuring device that work according to Archimedes law which states that the buoyant force acting on an object in a fluid is equal to the weight of the fluid displaced by the object . This allows the level to be inferred by measuring the apparent weight of the immersed displacer float. 28

Torque Tube Displacers External Cage Displacer Range Spring Linkage Torque Tube Transmitter Vertical Force Movement of Displacer and Rod is Converted to Angular Rotation of Torque Tube The torque tube displacer is the most common type of displacer used in process plants. It consists of an external cage which is connected to the vessel and provides the liquid level to be measured and houses the displacer which is used to measure the level. A range spring is provided to adjust for the measured fluid density since the displacer tubes come in standard sizes. The displacer has a shaft which is connected to the torque tube through a linkage. This linkage converts the up and down motion of the displacer to radial movement in the torque tube. The torque tube is connected to the transmitter which converts the torque tube movement to an analog signal. 29

Torque Tube Displacers Considerations Typical Measuring Range is 14” to 72” Mounting Orientation for Torque Tube Arm Fluid Density Vent and Drain Connections Require Jig Set Connections These are some things that should be considered when specifying torque tube displacers. Unlike differential pressure transmitters, displacers come in standard range lengths these are from 14 inches to 72 inches. The torque tube arm is generally long and can cause an obstruction. When Piping locates the displacer they will need to provide guidance on the required orientation. Since displacers operate on the buoyancy of the fluid the operation can be affected by changes in fluid density. It is also important to know the density at the time of order since the displacer float selection is based on this. Displacers should always be provided with vent and drain connections to allow for inline maintenance without taking the vessel out of service. The vessel connections must be jig set to ensure proper fit up of the transmitter cage if the displacer is directly connected to a vessel.. 30

Level Instrumentation Types – Guided Wave Radar
Dielectric Constant A Measure of a Material’s Ability to Conduct Electricity Read bullet and discuss. Definition needs to be understood by the student before proceeding. The lower the dielectric constant of a material the less conductive the material is. The higher the dielectric constant of a material the more conductive the material is. Water has a dielectric constant of 80. 31

Operating Philosophy Based on Time Domain Reflectometry (TDR) A Pulse of Electromagnetic Energy is Transmitted Down a Guide When the Pulse Reaches a Surface that has a Higher Dielectric than the Vapor Space it is Travelling in, then the Pulse is Reflected The Time Difference between the Transmitted and Reflected Pulse is Converted into a Distance from Which the Total Level or Interface Level is Calculated Read bullets on this slide and the next and discuss. A general description of a guided wave radar level transmitter operation. 32

Guide Types Coaxial Rigid Twin Lead Flexible Twin Lead Rigid Single Lead Flexible Single Lead Each Guide Type has a Maximum Measuring Range and Minimum Dielectric Constant Read bullets and discuss. 33

Considerations Dielectric Constants between 1.4 and 100 The Higher the Dielectric Constant the Greater the Reflected Pulse Transition Zones – Vary with Dielectric Constant To Stabilize the Guide Side Forces Either Install in a Stilling Well or Fix the Guide to the Tank Bottom Centering Discs which prevent the Guide from Contacting the Side of the Stilling Well Weights Should be used when Installing Flexible Guides Inlets should be kept at a Distance to Avoid Splashing on the Guide Select Guide Length According to the Required Measuring Range. Some Guides can be Cut in the Field, Others cannot Read bullets on this slide and the next and discuss considerations for using this type of technology. Dielectric constants are important to consider because the value will impact the reading or the readability of the process surface. Transition zones (or dead zones) also are important to consider because they can limit where and if a particular surface level can be read. Centering discs are an important option especially when using a flexible guide. 34

Level Instrumentation Types – Radar
Operating Philosophy Radar Signals are Transmitted from an Antenna at the Top of the Tank The Signal is Reflected by the Measured Surface and the Echo is Detected by the Antenna The Echo has a Slightly Different Frequency Compared to the Transmitted Signal The Frequency Difference is Proportional to the Distance to the Measured Surface Read bullets and discuss. A general description of a radar level transmitter operation. 35

Considerations Transmitter Should be Installed in Locations with a Clear and Unobstructed View of the Level Surface Keep Away from Agitator Horizontal Blades, Filling Inlets, Center of the Tank Minimum Distance that the Transmitter can be Mounted from the Tank Wall A Stilling Well can be Used to Avoid Disturbing Objects, Turbulence and Foam Choose the Largest Possible Antenna Diameter for Installation Tank Nozzle Height can Affect Performance Read bullets on this slide and the next and discuss considerations for using this type of technology. Most important to remember to keep away from any obstructions as they will reflect the radar pulse. 36

Antenna Types Rod – Suitable for Tanks with Small Openings Cone – Suitable for Free Propagation and Pipe Mounted Installations Parabolic – Suitable for Solids and Can withstand Heavy Contamination Each Antenna Type has a Maximum Measuring Range and Minimum Dielectric Constant Read bullets and discuss. Similar to a guided wave application, there are many different types of antennas each with their own suitable application. 37

Level Instrumentation Types – Float & Tape
Float and Tape A Large Stainless Steel Float is Attached to a Spring by a Perforated Tape The Spring Provides Constant Tension, which Balances the Float on the Liquid The Perforated Tape Engages Pins on a Sprocket Wheel that Drive the Counter Assembly Read bullet and discuss. A general description of a float and tape level device operation. Used almost extensively for tank gauging applications. Can be used as a locally indicating device or can have a signal brought back to the control room. 38

Pictures of some of the components of a float and tape assembly as well as a sketch for an possible installation on a fixed roof tank. 4/14/2017 39

Considerations Fluid Density Tank Roof Configuration Availability of 120 VAC Power Read bullets and discuss. Tank roof configuration is an important consideration to provide for a proper installation of the float and tape level device. Will power be available (only the case where required because of transmitter set-up). Cost of installation is high, however, this device is only typically used in tang gauging applications. Density need to be considered because the float is designed for a specific range and if the fluid density falls outside that range then the float will either ride higher or lower in the fluid giving an inaccurate level measurement. 40

Level Instrumentation Types – Float Switch
Float Level Switches use a Float and Magnetic Coupling Action As the Float Rises or Falls with a Liquid, it Moves a Sleeve into or out of a Magnetic Field, Causing Switch Operation A Non-Magnetic Barrier Isolates the Switch Mechanisms from the Liquid Read bullets and discuss. A general description of a float switch operation. It should be noted that most clients (if not all) are moving away from switch applications and are instead utilizing transmitters. 41

Level Instrumentation Types – Float Switch
Float Switch Configurations Vertical Horizontal Top Mounted Side Mounted Read bullets and discuss. Pictures of some possible float switch configurations. 42

Level Instrumentation Types – Ultrasonic
Operating Philosophy Based on Time Domain Reflectometry (TDR) Ultrasonic Pulse Signals are Transmitted from the Transmitter and are Reflected from the Liquid Surface The Transmitter Receives the Reflected Signal and Measures the Time-Delay Between Transmitting and Receiving Ultra sonic level transmitters use time domain reflectometry, like guide wave radars, to measure the fluid level. The difference being that they send ultrasonic signals from the transmitter and are they reflected from the liquid surface. The transmitter receives the reflected signal and measures the time-delay between transmitting and receiving. 43

Level Instrumentation Types – Ultrasonic
Considerations Mount Transmitter as Near to Vertical as Possible Avoid Obstructions in the Ultrasonic Beam Path Minimum Tank Nozzle Height Foam can Reduce Echo Returns Do not Mount Over an Inlet Stream Stilling Wells can be Used to Minimize the Effects of Turbulence and Foaming This type of technology is typically used in open, atmospheric tank water applications. It should be kept away from obstructions that could interfere with the reflected signal. It also should not be used in foaming or turbulent applications. 44

Level Instrumentation Types – Capacitance
A Measure of the Amount of Energy that can be Stored Capacitance is Influenced by Three Factors: Distance between the Electrode Plates Size of the Electrode Plates Dielectric Value of Material between the Electrodes Capacitance is also a measure of the amount of electric potential energy stored for a given electrical potential. Capacitance is Influenced by the distance between the electrode plates, their size and the dielectric value of the material between the electrodes. 45

Operating Philosophy As Level Covers the Sensing Probe, the Capacitance Between the Probe and Conductive Media or the Probe and the Vessel Wall Increases A Bridge Misbalance is Created which is Amplified and Converted to an Output that Corresponds to the Level the Vessel This Technology does not Measure the Amount of Energy Stored, but Rather the Amount of Energy that can be Stored Capacitance level sensors excel in sensing the presence of a wide variety of solids, aqueous and organic liquids, and slurries. The technique is frequently referred to as R, F capacitance for the radio frequency signals applied to the capacitance circuit. The sensors can be designed to sense material with dielectric constants as low as 1.1, such as coke or fly ash and also in a wide range of liquid applications. A capacitor is formed when a level sensing electrode is installed in a vessel. The metal rod of the electrode acts as one plate of the capacitor and the tank wall or reference electrode in a non-metallic vessel acts as the other plate. As level rises, the air or gas normally surrounding the electrode is displaced by material having a different dielectric constant. A change in the value of the capacitor takes place because the dielectric between the plates has changed. Radio frequency capacitance instruments detect this change and convert it into a proportional output signal. 46

Considerations Do not Mount in an Inlet Stream Stilling Wells Use Brackets and Supports in Agitated Vessels Ground the Probe when Installed in Non-Metallic Vessels Nozzle Diameter Probe Coating Capacitance probes can be used in a wide variety of liquids and solids applications. It can be located within the vessel or mounted in a cage. If mounted in the vessel a stilling well should be considered. The probe should be grounded when used with non-metallic vessels. If there is a chance of coating on the probe R, F admittance technology should be used. 47

Level Instrumentation Types – Nuclear
Operating Philosophy Source Radioisotopes used for Level Measurement Emit Gamma Radiation that Penetrates the Vessel Wall and Process Media A Target Detector on the Opposite side Measures the Radiation Field Strength and Infers a Level in the Vessel The Radiometric or Nucleonic Principle is Based on the Fact that Gamma Radiation is Attenuated when it Penetrates a Material Cesium 137 (Half Life 30 Years) and Cobalt 60 (Half Life 5.26 Years) are the Most Commonly Used Industrial Isotopes Nuclear level measurement is made through the application of a radioactive source, normally cesium 137 or cobalt 60 and detector also called a scintillator. These are mounted on opposite sides of the tank, there will be a certain amount of radioactive energy that will penetrate the tank and be detected on the other side. When there is more process fluid in the vessel, there will be more energy absorbed by the process fluid. Hence, the amount of nuclear energy being received by the detector will decrease. This energy can be correlated to level. Regardless of the process conditions, nuclear level will almost always work. Extreme temperatures and pressures, vessel obstructions, corrosive and erosive applications are great applications for nuclear level measurement. Due to a number of factors this is typically the level measurement selection of last resort. 48

Geiger Tube Detectors are Used to Measure the Amount of Radiation Received and Hence the Level in the Vessel Lead Lined Source Holders Contain Radioactive Material with a Slit to Send a Narrow (in Horizontal Plane) Fan Beam Across the Vessel Source Strength has to Consider Vessel Wall Thickness Nucleonic Level is Considered for the Most Difficult Applications such as High Temperatures and Pressures, Toxic, Sticky/Blocking Materials. It is Used as a Last Resort. Geiger tube detectors are used to measure the amount of radiation received and from this imply the level in the vessel. These devices use a lead lined source holder to contain the radioactive material with a slit to send a narrow fan beam across the vessel. They require special handling, licensing and technical training to install and maintain. The source strength has to consider vessel wall thickness since it will attenuate the signal. Additional consideration has to be taken into account for the deterioration of the nuclear source as it decays as this will cause a loss of signal strength.. Nucleonic level is only considered for the most difficult applications such as high temperatures and pressures, toxic, sticky/blocking materials. It is used as a last resort. 49

SOURCE DETECTOR DETECTOR SOURCE These diagrams show two different methods for measuring level. On the left is a point source with a rod style detector and on the right is a rod style source with a point detector. The point source is generally used for liquid measurement while the rod source is used for solids measurement. 50

Level Instrumentation Concepts – Tank Gauging
Tank Gauging is associated with Large Volumes of High Value Product Additional Measures are Taken to Achieve the Highest Possible Measurement of Level and Volume Correction Most process plant have large tank farms for storing raw materials and intermediate and final products. It is important for plant operations to know the quantities stored in each tank. Tank gauging is used for measuring large volumes of product that have a high value. It is imperative to have high accuracy since this revolves around product storage. This is either where the client gets billed for accepting some product or where the client makes money on the product he has produced in his plant. 51

This is Essential for: Stock Control for Production and Gains/Losses Asset Reporting for Tax Purposes Emissions Monitoring Via Tank Level Changes for Leakages Blending between Tanks of Out-of-Spec Product with In-Spec Product Cross Checks on Ship Loading/Off Loading Flow Meters and Ship Dips Tank gauging is essential for control of production both purchasing and sales, asset reporting for taxes, and cross checking the loading of ships or contains or off loading of ships or containers. 52

Tank Farm Level Configuration Tank Inventory Monitoring Radar Level Measurement on Fix Roof Tanks Float and Tape Level Measurement on Fixed Roof Tanks Local Display and Multiplexer Local Display and Multiplexer Servo Level Measurement on Spheres Tank gauging may utilize a number of different technologies for measuring the products stored in tanks depending on the tank contents and tank design. This diagram shows how different devices are utilized and interconnected. All are connected on the tank gauging highway back to a central inventory monitoring system located in a control room. This monitoring system is most likely tied into the plant D, C, S and that systems historian computer. Radar Level Measurement on Floating Roof Tanks Bus Communication Local Display and Multiplexer 53

Level Instrumentation Overview - Summary
There is no single level measurement technique that will work in all applications. Proper installation is important for level not just for accuracy but for getting a measurement reading at all. Continuation of the general concepts that the student should have gotten from this training course. 54

Any Questions??? QUESTIONS
This completes the Control Systems Training Module CSE156.1 Flow Instruments. Are there any questions?

Thanks for your attendance

Mark Murphy, PE Technical Director, Fluor Corp.

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