basic instrumentation for oil gas industries_presentation_29.08.10

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BASIC INSTRUMENTATION BASIC INSTRUMENTATION FOR FOR OIL / GAS INDUSTRIES OIL / GAS INDUSTRIES

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Page 1: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

BASIC INSTRUMENTATION BASIC INSTRUMENTATION FOR FOR

OIL / GAS INDUSTRIESOIL / GAS INDUSTRIES

Page 2: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

INDEXINDEX

I.I. INTRODUCTIONINTRODUCTION

II.II. BASIC INSTRUMENT ITEMSBASIC INSTRUMENT ITEMS

III.III. BASIC MEASURING INSTRUMENTSBASIC MEASURING INSTRUMENTS

IV.IV. INTER DESCIPLINE CO-ORDINATIONINTER DESCIPLINE CO-ORDINATION

V.V. INSTRUMENT DESIGN ACTIVITIESINSTRUMENT DESIGN ACTIVITIES

VI.VI. INSTRUMENT STANDARD SYMBOLS AND PRESENTATIONINSTRUMENT STANDARD SYMBOLS AND PRESENTATION

VII.VII. TYPICAL INSTRUMENT INSTALLATIONTYPICAL INSTRUMENT INSTALLATION

VIII.VIII. TYPICAL CONTROL ROOM LAYOUTTYPICAL CONTROL ROOM LAYOUT

Page 3: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

I. INTRODUCTIONI. INTRODUCTION

Page 4: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

Instrumentation is playing vital role in Instrumentation is playing vital role in the Process Industries today. the Process Industries today.

Apart from achieving maximum Apart from achieving maximum production at minimum cost, production at minimum cost, instrumentation also ensures product instrumentation also ensures product quality and safety of quality and safety of equipment/machinery and operating equipment/machinery and operating personnel.personnel.

Page 5: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

EVOLUATION OF INSTRUMENTATION TECHNOLOGYEVOLUATION OF INSTRUMENTATION TECHNOLOGY

Pneumatic System – 3 to 15 Psi Signal (up to 70’s)Pneumatic System – 3 to 15 Psi Signal (up to 70’s)Analogue(Microprocessor based) System – 4 to 20 Analogue(Microprocessor based) System – 4 to 20 mA Signal (70’s Onwards)mA Signal (70’s Onwards)Distributed Control System (DCS) (80’s Onwards)Distributed Control System (DCS) (80’s Onwards)Fieldbus System (90’s Onwards)Fieldbus System (90’s Onwards)Wireless Instrumentation System (2000 Onwards)Wireless Instrumentation System (2000 Onwards)

Page 6: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

II. BASIC INSTRUMENT ITEMSII. BASIC INSTRUMENT ITEMS

Page 7: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

o Measuring Instruments (Flow, Level, Pressure, Measuring Instruments (Flow, Level, Pressure, Temperature, Weight, Speed, Vibration, etc.)Temperature, Weight, Speed, Vibration, etc.)

o Control Instruments (Panel Instruments, PLC, DCS, Control Instruments (Panel Instruments, PLC, DCS, SCADA, etc.)SCADA, etc.)

o Analyser (pH, Conductivity, DO, CO, CO2, O2, NOX, Analyser (pH, Conductivity, DO, CO, CO2, O2, NOX, SO2 etc.)SO2 etc.)

o Control Valve (Pneumatic actuated, Motor actuated, Control Valve (Pneumatic actuated, Motor actuated, Piston actuated, etc.)Piston actuated, etc.)

o Safety Valve ( Safety Relief, Thermal Relief, etc.)Safety Valve ( Safety Relief, Thermal Relief, etc.)

Page 8: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

III. BASIC MEASURING INSTRUMENTSIII. BASIC MEASURING INSTRUMENTS

Page 9: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

Instrumentation for any process monitoring Instrumentation for any process monitoring could be divided by 3 categories.could be divided by 3 categories.

1. Essential instrumentation for monitoring 1. Essential instrumentation for monitoring process parameters and ensuring safety in process parameters and ensuring safety in plant operation.plant operation.

2. Instrumentation for enhancing plant 2. Instrumentation for enhancing plant efficiency and cutting down cost of efficiency and cutting down cost of production.production.

3. Instrumentation to provide reliable data 3. Instrumentation to provide reliable data for management/cost accounting and for management/cost accounting and saving human labour.saving human labour.

Page 10: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

Now I will limit my discussion to category Now I will limit my discussion to category 1 and will cover measurement of the 1 and will cover measurement of the following basic process parameters.following basic process parameters.

– Flow MeasurementFlow Measurement– Pressure MeasurementPressure Measurement– Level MeasurementLevel Measurement– Temperature Temperature

MeasurementMeasurement

Page 11: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

Fluid flow is very important in all Fluid flow is very important in all Chemical Process Industries including Chemical Process Industries including the Oil & Gas industry. the Oil & Gas industry. There is hardly any process or selection There is hardly any process or selection of this industry where fluid flow in some of this industry where fluid flow in some form or other is not encountered. form or other is not encountered. Flow measurement is necessary for Flow measurement is necessary for material and energy balances and for material and energy balances and for cost and quality control. Hence, this cost and quality control. Hence, this measurement is of prime importance in measurement is of prime importance in industry industry

1.0 1.0 FLOW MEASUREMENTFLOW MEASUREMENT

Page 12: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

While selecting a flow metering device for a particular While selecting a flow metering device for a particular application, the following factors should be taken into application, the following factors should be taken into consideration:consideration:

a. Rangeabilitya. Rangeabilityb. Accuracy of measurement requiredb. Accuracy of measurement requiredc. Costc. Costd. Fluid Condition (Clean or entrained d. Fluid Condition (Clean or entrained

solids)solids)e. Flow Conditions (Pressure, e. Flow Conditions (Pressure,

temperature, temperature, viscosity etc.) viscosity etc.)f. Corrosiveness of fluids.f. Corrosiveness of fluids.

Page 13: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

g. Installation and maintenance g. Installation and maintenance requirementsrequirements

h. Reliabilityh. Reliabilityi. Type of read out required – i. Type of read out required –

Local/Panel.Local/Panel.j. Pressure loss available.j. Pressure loss available.k. Requirement of power i.e. electricity, k. Requirement of power i.e. electricity,

compressed air etc.compressed air etc.l. External environment requirements l. External environment requirements

due due to corrosive or hazardous atmosphere.to corrosive or hazardous atmosphere.

Page 14: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

For proper selection and measurement of process For proper selection and measurement of process parameters, services conditions must be known and parameters, services conditions must be known and listed in detail. For example for Flow Measurement listed in detail. For example for Flow Measurement the following conditions should be known & listed.the following conditions should be known & listed.1.1.Line size.Line size.2.2.Range of flow rates – min, normal and maximum.Range of flow rates – min, normal and maximum.3.3.Fluid characteristics – Fluid characteristics – a) Liquid, gas, slurry a) Liquid, gas, slurry b) Temp. b) Temp. c) Pressure c) Pressure d) Viscosity d) Viscosity e) Compressibility e) Compressibility f) Degree of superheat for steam f) Degree of superheat for steam g) Molecular wt. g) Molecular wt. 4. Corrosive effects.4. Corrosive effects.5. Whether flow is pulsating.5. Whether flow is pulsating.

Page 15: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

Inferential measurementInferential measurement Direct quantity Direct quantity measurement measurement

Mass flow measurement Mass flow measurement

1.1. Variable area type Variable area type (Rotameter)(Rotameter)

1. Positive displacement 1. Positive displacement Meters. Meters.

1. Impeller turbine meter 1. Impeller turbine meter Which responds to rate of Which responds to rate of mass flow.mass flow.

2. Variable Head type (D.P. 2. Variable Head type (D.P. Meters) Meters) 2. Oval gear Meters2. Oval gear Meters

2. Volume flow rate meter with 2. Volume flow rate meter with automatic density automatic density correction.correction.

3. Magnetic flow meter3. Magnetic flow meter

4. Turbine meter4. Turbine meter

5. Target meter5. Target meter

6. Swirl meter6. Swirl meter

7. Vertex meter7. Vertex meter

8. Sonic meter8. Sonic meter

9. Pitot tube9. Pitot tube

MEASUREMENT METHODS AND METERSMEASUREMENT METHODS AND METERS

Page 16: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

1.1 Variable Area Meters (Rotameters)1.1 Variable Area Meters (Rotameters)

Advantage1. Good rangeability.2. Relatively low cost.3. Good for metering low flows.4. Easily equipped with alarm switches.5. No restrictions in regard to inlet and outlet piping

requirements (other than vertical flow requirements).6. Low pressure drop requirement.7. Can be used in some light slurry services.Disadvantages/Limitations1. Glass tube types subject to breakage.2. Not good in pulsating services.3. Must be mounted vertically.4. Generally limited to small pipe sizes (unless bypass

rotameter is used).5. Limited to relatively low temperature.6. Require in-line mounting (except by-pass type).

Page 17: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

1.2 Variable Head and Diff. Pressure Meters1.2 Variable Head and Diff. Pressure Meters

This type of meter though one of the oldest, is still used extensively. It outsprings all other types of flow meters because of simplicity, accurate and reliable measurement and low cost. It measures the flow which is proportional to the differential pressure created across the restriction. The summary of various primary elements under this category is shown in next slide:

Page 18: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

Primary Primary elementelement FluidFluid

Permanent Permanent Pressure- Pressure-

losslossRange- Range- abilityability AccuracyAccuracy Upstream Upstream

pipingpiping CostCost Velocity Velocity effecteffect

OrificeOrifice Liquid, gasLiquid, gas 50-90%50-90% 3:13:1 ±¾ -1%±¾ -1% 10D-30D10D-30D Low Low HighHigh

Venturi Venturi TubeTube Liquid, gasLiquid, gas 10-20%10-20% 3:13:1 ±1%±1% 5D-10D5D-10D Very HighVery High Very HighVery High

Flow Flow NozzleNozzle Liquid, gasLiquid, gas 30-70%30-70% 3:13:1 ±1%±1% 10D-30D10D-30D MediumMedium HighHigh

Pitot Pitot TubeTube Liquid, gasLiquid, gas NILNIL 3:13:1 VariableVariable 20D-30D20D-30D LowLow LowLow

Page 19: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

Advantages 1. Relatively low cost, especially for large lines.2. Proven accuracy and reliability well known and predictable

flow characteristics.3. Secondary or diff. device easily isolated for zero check or

calibration.4. Adaptable to any pipe size5. Cost remains almost the same with increasing pipe size.

Disadvantages/Limitations1. Flow rangeability is 3:12. Relatively high permanent pressure loss.3. Difficult to use for slurry services.4. Square root characteristics.5. Straight run lengths required for accurate measurement

some times present problems.6. Pulsating flow difficult to measure.7. Accuracy is dependent of fluid characteristics such as

pressure, temperature, viscosity etc.

Page 20: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

CONCENTRIC ORIFICE PLATE

Advantages

1. Low cost2. Available in many materials3. Can be used for wide range of pipe materials4. Good accuracy if Orifice plate is properly installed

Disadvantages

1. Relatively high permanent pressure loss2. Accuracy depends on installation.3. Tend to clog, reducing its use in slurry service.

Page 21: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

VENTURI TUBES

Advantages

1. Low permanent pressure loss.2. Can handle suspended solids.3. Used for higher flow rates.4. Well known characteristics.5. More accurate over wide flow range than Orifice plate.

Disadvantages

1. High cost.2. Not normally available line size below 6”,

Page 22: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

FLOW NOZZLE

Advantages

1. Permanent pressure loss lower than Orifice plate.2. Available in numerous materials.

Disadvantages

1. Higher cost than Orifice plate.2. Limited to moderate pipe sizes.

Page 23: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

PITOT TUBE

Advantages

1. Essentially no pressure loss.2. Economical to install.3. Some types can be removed from the lines.

Disadvantages

1. Poor accuracy2. Not recommended for dirty or sticky fluids.3. Calibration data need to be supplied from manufacturer.

Page 24: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

1.3 Magnetic Flow Meters1.3 Magnetic Flow Meters

These are used primarily in difficult to measure services where other, more economical type do not function well. They are particularly well suited for slurry and corrosive services but require that the measured fluid be electrically conductive. No pressure drop except straight line loss. Accuracy is unaffected by pressure, viscosity, density or character of flow. Response is linear with flow rate. The flow is inferred from velocity of fluid.

Page 25: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

Advantages1. Can handle slurries2. Can handle corrosive fluids3. Has very low pressure drop.4. No obstruction in pipe5. Available in many construction materials6. Available in large pipe sizes.7. Piping configuration not critical8. Bidirectional flow measurement9. Measurement unaffected by viscosity, density, temperature or

pressure10. Can measure turbulent or laminar flow11. Unaffected by conductivity change

Disadvantages1. Fluid must be conductive with minimum value required by

particular manufacturer.2. Meters must be full all time3. Relatively high in cost4. Entrained gas, bubbles result in measurement error5. In-line mounting required6. Meter must be explosion proof when installed in hazardous area

Page 26: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

1.4 Turbine Meters1.4 Turbine Meters

These meters are used for applications where high accuracy of the order of ±0.25% is required. The repeatability is excellent and the rangeability is also good. This is popularly used for the measurement of flow of ammonia. Here the velocity of fluid causes the rotor of the turbine meter to rotate at a speed which is proportional to the flow rate. The rotation of the rotor is counted by a magnetic pick-up which generates pulses. The output of the magnetic pick-up is fed to the digital instrument for indication or totalisation.

Page 27: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

Advantages1. Good accuracy 2. Excellent repeatability3. Excellent rangeability4. Low pressure drop5. Easy to install and maintain6. Can be compensated for viscosity variations7. Adaptable to flow totalizing8. Good temp. and pressure rating.

Disadvantage/Limitations1. In line mounting required2. Relatively high cost3. Limited use for slurry applications4. Non-lubricating fluids some times present

problems5. Straight run of pipe required ahead of the meter6. Strainers/vapour eliminators recommended for

these meters.

Page 28: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

2.0 PRESSURE MEASUREMENT2.0 PRESSURE MEASUREMENT

The selection of pressure devices is not as difficult as selecting flow or level devices. In pressure measurement the emphasis is less on fluid characteristics and more on consideration of accuracy, range of measurement and material selection. The pressure elements are generally divided into the following categories.

1. Manometer2. Bourdon Tube3. Bellows4. Diaphragm elements5. Strain gauges6. Chemical seal

Page 29: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

2.1 Manometers2.1 Manometers

In early days of process instrumentation, their use was more frequent, but now-a-days these are occasionally used for low pressure services (few inches of water).

Advantages1. Simple and time proven2. High sensitivity3. Moderate cost4. Particularly suitable for low pressure

and low diff. applications5. Wide range of filling fluids of varying

specific gravities.

Disadvantages/Limitations1. Lack of portability2. Need leveling3. Generally large and bulky4. No over range protection5. Condensation may present problem

Page 30: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

2.2 Bourdon Elements2.2 Bourdon Elements

C-type, helical and spiral type bourdon elements comprises a high % of all pressure applications. Most local pressure gauges and receiver gauges utilizes the C-type bourdon tube.

•C-type – pressure range – 1 to 7000 Kg/cm², accuracy range ± 1% to ± 5%

•Spiral element – press. Range – upto 7000 kg/cm², accuracy ±0.5%

•Helical element – press. Range – 7 to 5500 kg/cm², accuracy ± 0.5 to 1%

Page 31: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

Advantages1. Low cost2. Simple construction3. Years of experience in

application4. Available in wide variety of

range5. Good accuracy specially when

considered in relation to cost.Disadvantages/Limitations

1. Susceptible to shock and vibration2. Subject to hysteresis

Page 32: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

2.3 Bellows Elements2.3 Bellows Elements

Most bellows elements are used for low pressure and differential pressure services. These are widely used as differential units for flow measurements particularly in field mounted indicators/recorders.

These units operate from vacuum service upto 0-30 Kg/cm². Some units are available that operate upto 0-150 kg/cm². Accuracy is in the range of ± 0.5%.

Page 33: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

Advantages1. Moderate cost2. Adaptable for absolute and

diff. pr. use.3. Good in low-to moderate

pressure range.

Disadvantages/Limitations1. Need ambient temp.

compensation2. Not suitable for high pressure3. Limited by material of

construction

Page 34: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

2.4 Diaphragm Elements2.4 Diaphragm Elements

These are used in vacuum and pressure services, in motion and force balancing units.

The normal application range is from vacuum upto 15 Kg/cm² special diaphragm units are available for pressure upto 700 Kg/cm². Accuracy range from ± ½ to 1 ½ % of full span.

Page 35: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

Advantages1. Moderate cost2. Small in size3. High over range

characteristics4. Linearity is good5. Adaptable to slurry services6. Available in several materials

for good corrosion resistanceDisadvantages/Limitations

1. Does not have good vibration and shock resistance

2. Difficult to repair

Page 36: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

2.5 Strain gauges2.5 Strain gaugesThese gauges find limited use in process industry. Accuracy ranges from ± 1% of span.

Advantages

1. Small and easy to install2. Good accuracy3. Available for wide range of

measurement – from vacuum to 14000 kg/cm²

4. High output signal strength5. High over range capacity6. No moving parts7. Good shock vibration

characteristics8. Fast speed of response.

Page 37: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

Disadvantages/Limitations

1. Moderate to high cost2. Electrical read out necessary3. Require constant voltage supply4. Temp. compensation usually

necessary

Page 38: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

2.6 Chemical Seals2.6 Chemical Seals

These are used to isolate process materials from measuring elements due to

1. To prevent clogging of the measuring elements.

2. To prevent the corrosive materials from reaching the measuring element because of cost and other factors.

3. To prevent process fluid from freezing/vaporizing.

Disadvantages1. Additional cost2. Possible reduction in accuracy, ambient

temperature variation effects on filling fluid may cause some error.

Page 39: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

3.0 LEVEL MEASUREMENT3.0 LEVEL MEASUREMENTThe selection of proper level measurement

method is probably more difficult for any of the four major process variables except flow. As in flow measurement the conditions of measured media have many adverse effects on measuring devices.

Level Range(Selection criterias)1. Fluid Characteristics (a) Temp. (b) Pressure

(c) Sp. Gr. (d) whether fluid is clean or dirty, contains vapors or solid etc.2. Corrosive Effects3. Whether fluid has a tendency to “coat”

vessel walls or the measuring devices.4. Whether fluid is turbulent around the

measurement area.

Page 40: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

3.1 Displacer element type

The Displacement or buoyancy method was for many years the most widely used technique for measuring liquid levels.

It is still popular for clean fluids, but many processes that slurries, have tendencies to “coat” have wide ranges etc. require other, more acceptable methods.

Page 41: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

Advantages1. High accuracy.2. Reliable in clean liquid3. Proven method4. Can be mounted internally or externally5. Externally mounted units can be valved

off for maintenance

Disadvantages1. Has limited range unit exceeding

48” in length are bulky difficult to handle.

2. Costs increase appreciably for externally mounted units as pressure rating increases.

3. External units may require heating to avoid freezing.

4. External unit may be in error because of temp. differences between the vessel fluid and level chamber fluid.

Page 42: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

3.2 Differential Pressure TypeThe use of diff. pressure measurement for level

determination has increased significantly in the past few years. Several different types of differential devices make it possible to measure wide level ranges for clean or corrosive services for slurries and for highly viscous materials. Almost any type of D.P. devices can be used for level measurement if it is available in low ranges normally required for level, usually from about 10” water to approximately 150” of water, they are broadly classified into two groups. Sealed & non-sealed system.

a. Non-sealed system – Differential units such as the d/p cell used for flow measurement are used for measuring levels. They may be used directly in contact with fluid or may be purged with suitable gas or liquid sources.

Page 43: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

Advantages 1. Good accuracy2. Adaptable to wide level range3. Adaptable in many construction

materials/or can be purged for corrosive liquid.

4. Can be purged for use in slurry service

5. Moderate cost6. Can be isolated

Disadvantages1. Errors caused by density

variation2. Low pr-headline often

undesirable in other than atmospheric application

3. Heating of lead lines sometimes necessary

4. Operating & maintenance problems often presented by purged lines.

Page 44: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

b. Sealed system – To meet application requirements for some slurries & highly viscous materials, sealed system.

Advantages 1. Purge not required

2. Good for slurries and corrosive materials3. Sensing units essentially flush with

operating fluid eliminating cavities where plugging & freezing are likely to occur.

4. Wide measurement range5. Wetted diaphragms can be furnished in a

wide variety of materials6. Fair accuracy7. Can be used for open or closed vessels8. Good for relatively high temperature

Page 45: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

Disadvantages

1. Unit cannot be removed for checking and/or maintenance without shutting down the equipment.

2. Density variations cause errors.

3. The mounting location affects calibration since the head of capillary filled legs must be considered.

4. Ambient temp. changes cause errors in capillary filled system type.

Page 46: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

3.3 Capacitive Type

Capacitance level measurement need to be separated into two categories for evaluation. Continuous & point. Continuous measurements are not made frequently with capacitance probes but work well in some applications. However, they are used often for point measurements and are superior for many applications.

a. Continuous Measurement: For the infrequent use in continuous level applications the capacitance methods have several advantages & disadvantages

Page 47: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

Advantages1. Can be used for some application where other

type ore not feasible.2. Moderate cost3. Fair accuracy4. Can be used for high temp & high pressure

applications5. Can be used in polymer & slurry services

Disadvantages1. Special calibration required in many instances2. Affected by density variations of measured

materials3. Limited application data

Page 48: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

b. Point Measurement: For the infrequent use in continuous level applications the capacitance methods have several advantages & disadvantages

Advantages1. Reasonable cost2. Easy to install3. Useful on applications such as powders, pellets &

other solid containing materials, as well as slurries & corrosive materials where many other level devices will not work

4. Simple in design5. No moving parts

Disadvantages1. Accuracy affected by material characteristics2. Coating of probes troublesome on same design3. Lack of data on diebatric constraints of same

material

Page 49: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

3.4 Radiation TypeThe radiation type is used both for continuous &

point level measurement generally, it is expensive method to use and is considered seriously only when it is obvious than other, less expensive, methods are not very likely to be satisfactory.

a) Continuous system: Continuous system for radiation level gauging is expensive. Not only is the hand were costly, but calibration & testing can also be time consuming. Thus adding operating cost. Since they are so often used as a last resort method and are successful in most instances, their overall cost may still be considered economical.

Page 50: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

Advantages1. Sometimes works when no other method is

available2. External mounting often possible3. Easy zero check

Disadvantages1. Costly to install2. Requires licensing by regulatory agency3. Dangerous to handle unless precautions are

followed4. Original calibration & checkout often difficult &

costly5. Errors caused by density variations in measured

materials6. Lack of application data7. Difficult to obtain in linear readout over wide range8. Problems presented by materials that coat walls

Page 51: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

b) Point measurement: Point measurement is not nearly as difficult to make as continuous measurement. Calibration is also relatively easy.

Advantages1. Sometimes works when no other method is available2. External mounting often possible3. Easy zero check

Disadvantages1. Costly to install2. Requires licensing by regulatory agency3. Dangerous to handle unless precautions are followed4. Original calibration & checkout often difficult & costly5. Errors caused by density variations in measured

materials6. Lack of application data7. Difficult to obtain in linear readout over wide range8. Problems presented by materials that coat walls

Page 52: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

3.5 Rotating Paddle Type

Paddle switches are used primarily on level application for solid materials such as powders & pellets. They are relatively inexpensive & easy to install. They need to be placed in a position where they are protected from inflowing streams. When this is not feasible a protecting baffle should be placed above the unit some switch model has been subject to failures because five powders enter shaft seals causing false alarms. This can be prevented by proper sealing of shafts.

Page 53: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

4.0 Temperature Measurement

Temp. is probably most widely measured and frequently controlled of the process variables. There are many industries in which the measurement and control play a critically important part. For example, in the manufacture of steel the temperature to which liquid steel is heated in the furnace affects the final product in several ways. The rate of chemical reactions rapid with increasing temp., in some cases by a factor of 2 or 3 for every 10ºC rise in temperature.

In selection of temperature devices is not as difficult as selecting flow or level device. Unlike flow and level measurements where some devices simply will not work, most of the temperature measuring devices in common use would work in majority of applications the choice rests on cost, accuracy, response, maintainability and preference. Some of the common used temperature devices are: -

• Filled System• Thermocouples• Resistance Bulb• Bimetal thermometer• Pyrometer

Page 54: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

4.1 Filled System

Filled systems were among the early method used for process temperature measurement. The method was and still is a satisfactory way of measuring temperature for local indication. These systems can be divided into the following.

CLASCLASSS

Filling Filling MediumMedium

RangeRange ScaleScale ResponsResponsee

II LiquidLiquid -125 to 600ºF -125 to 600ºF UniformUniform 5-10 Sec5-10 SecIIII VapourVapour -430 to 600ºF -430 to 600ºF Not UniformNot Uniform 5-10 Sec5-10 SecIIIIII GasGas -400 to 1500ºF -400 to 1500ºF UniformUniform 1-5 Sec1-5 SecIVIV MercuryMercury -40 to 1000ºF -40 to 1000ºF UniformUniform 4-5 Sec4-5 Sec

Page 55: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

Advantages1. Simple, time-proven measurement method2. Relatively low cost3. No outside source of power required4. Narrow spans available5. Raggedly constructed6. Presents no electrical hazards

Disadvantages1. Limited to measurement below 1500ºF.2. Relatively slow response (fast enough for most

application)3. Bulb failure required replacement of the entire

system4. Transmission distances limited.

Page 56: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

4.2 Thermocouple

Thermocouple temperature measurement comprises a high percentage of those made in process industries. For remote process temp checkpoints they are used as exclusively bimetal thermometers are of local readout.

.

Page 57: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

Sr. No.Sr. No. TypeType Temp. Range º FTemp. Range º FLimits of ErrorLimits of Error

StandardStandard SpecialSpecial

11 K – Chromel/Alumel K – Chromel/Alumel 32 to +53032 to +530+530 to +2300 +530 to +2300

± 4 ºF± 4 ºF± ¾ % ± ¾ %

± 2 ºF± 2 ºF± 3/8 % ± 3/8 %

22 S – Pt/Pt-10% Rh S – Pt/Pt-10% Rh 32 to 1000 32 to 1000 ± 5 ºF ± 5 ºF - - 33 R – Pt /Pt-13% Rh R – Pt /Pt-13% Rh +1000 to +2700 +1000 to +2700 ± ½% ± ½% - - 44 J – Iron/Constants J – Iron/Constants 32 to +53032 to +530

+530 to 1400 +530 to 1400 ± 4 ºF± 4 ºF± ¾ % ± ¾ %

± 2 ºF± 2 ºF± 3/8% ± 3/8%

Page 58: Basic Instrumentation for Oil Gas Industries_presentation_29.08.10

Advantages1. Small unit that can be mounted conveniently1. Wide variety of designs for standard & special application2. Electrical output adaptable to a variety of readout &/or control

devices3. Response speed high compared to filled system4. Wide measurement range – from near absolute zero to 5000

ºF5. Low cost6. Good accuracy7. Calibration checks made easily8. Transmission distances can be long 9. Good repeatability

Disadvantages1. Temperature – voltage relationship not fully linear2. Accuracy less than that of resistance bulb3. Stray voltage pickups must be considered4. Temperature spans not as narrow as filled system or resistance

bulbs.5. Hot junctions “Age” in same services6. Requires expensive accessories for control application

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4.3 Resistance Bulbs

Resistance bulbs in the past have been used frequently and only for applications requiring high accuracy and/or narrow spans.

Advantages1. High accuracy2. Narrow span3. Reproducibility is good4. Remain stable & accurate for many years

Disadvantages1. Relatively expensive compared to

thermocouples2. Bulb sizes larger than thermocouples3. Mechanical abuse or vibration can be problem

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4.4 Radiation PyrometerRadiation pyrometers are used primarily for high & very

high temperature above ranges normally covered by thermocouples. They find limited use in chemical processing industries.

Advantages1. Ability to measure high temperature2. Does not require contact with target of measurement3. Fast response speed4. High output5. Moderate cost

Disadvantages1. Nonlinear scale2. Subject to errors due to presence of intervening

gases of vapors that absorb radiating frequencies3. Measurement affected by emissivity or target

material

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4.4 Bimetal Thermometer

Bimetal thermometers are used extensively for local indication of process temperature. They cost more that glass stem thermometers, but the additional cost is justified because glass thermometers are so easily broken.

Measurements can be made from about – 100 to 1000 ºF, minimum span is about 30 ºF. The scale is linear over most of the range. Accuracies range from ± ½ to ± 2% or higher.

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Advantages1. Low cost2. Not easily broken3. Easy to install & maintain4. Good accuracy relative to cost5. Fairly wide temperature range

Disadvantages1. Limited to local mounting2. Indicating only3. Calibration may change if handled roughly4. Not as accurate as glass stem thermometer.

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IV. INTER DESCIPLINE CO-ORDINATIONIV. INTER DESCIPLINE CO-ORDINATION

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V. INSTRUMENT DESIGN ACTIVITIESV. INSTRUMENT DESIGN ACTIVITIES

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Receive P & ID from Process Department

Prepare Instrument List

Verification of Control Valve Size

Selection of Instrument Ranges

Prepare specification sheet of Instrument

Prepare Control Panel Drawings

Prepare Control Room Equipment List

Prepare Mounting & Hook-up drawing.

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Prepare Loop drawing for field instrument

Prepare Control Loop schematics

Programmable logic controller (PLC) Preliminary I/O Estimation

Prepare Programmable Logic Controller (PLC) Input/Output List

Prepare Alarm List

Prepare Junction Box Schedule

Prepare Cable Schedule

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Prepare Cable specification and calculate total quantity.

Release indent for Enquiry.

Carry out technical evaluation of offers

Discussion with the bidders

Review vendor drawing for instrument

Prepare Material take offs

Technical evaluation of vendor for approved vendor list

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VI. INSTRUMENT STANDARD SYMBOLS AND VI. INSTRUMENT STANDARD SYMBOLS AND PRESENTATIONPRESENTATION

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6.1 Instruments Line Symbols (Ref. ISA S 5.1)

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6.2 General Instruments and Function Symbol (Ref. ISA S 5.1)

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6.3 Control valve body symbols, damper symbols (Ref. ISA S 5.1)

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6.4 Actuator symbols (Ref. ISA S 5.1)

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6.5 Symbols for self-actuated regulators, valves, and other devices (Ref. ISA S 5.1)

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6.6 Symbols for actuator action in event of actuator power failure (shown typically for diaphragm-actuated control valve). (Ref. ISA S 5.1)

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6.7 Primary element symbols (Ref. ISA S 5.1)

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6.7 Primary element symbols (contd.) (Ref. ISA S 5.1)

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6.7 Primary element symbols (contd.) (Ref. ISA S 5.1)

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6.7 Primary element symbols (contd.) (Ref. ISA S 5.1)

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6.7 Primary element symbols (contd.) (Ref. ISA S 5.1)

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6.7 Primary element symbols (contd.) (Ref. ISA S 5.1)

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6.7 Primary element symbols (contd.) (Ref. ISA S 5.1)

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6.7 Primary element symbols (contd.) (Ref. ISA S 5.1)

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6.7 Primary element symbols (contd.) (Ref. ISA S 5.1)

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6.7 Primary element symbols (contd.) (Ref. ISA S 5.1)

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6.8 IDENTIFICATION LETTERS (Ref. ISA S 5.1)

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VII. TYPICAL INSTRUMENT INSTALLATIONVII. TYPICAL INSTRUMENT INSTALLATION

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Pressure Gauge (Liquid/Gas Service)

Pressure Gauge (Steam Service)

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Pressure Gauge (Diaphragm Seal Type)

Pressure Switch

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PT (Gas / Vapour)

PT Remote Seal (Liquid Appl.)

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DPT for Level Appl.DPT Remote Seal for Level Appl.

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DP FT (Liquid Service) DP FT (Gas Service)

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Magnetic FT (Horizontal Mounting)

FT (Vortex Type)

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Level Gauge

Level Transmitter/Switch (Displacer Type)

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LT (Ultrasonic Type)

LT (Radar Type)

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Temp. Element (Line Mounted)

Temp. Gauge (Pipe/Tank Mounted)

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Control Valve ON-OFF Valve

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VIII. TYPICAL CONTROL ROOM LAYOUTVIII. TYPICAL CONTROL ROOM LAYOUT

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Typical Control Room Layout

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