Technical Standards for Transmitters

8/6/2019 Technical Standards for Transmitters

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Presentation onPresentation on

Technical Standards for TransmittersTechnical Standards for Transmitters

By : AJIT N. AHUJA


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DefinitionDefinition : It is a device which :: It is a device which :

Converts a Process Variable into a standard signal ofConverts a Process Variable into a standard signal of

Analog (4Analog (4--20 mA) and Digital superimposed on 420 mA) and Digital superimposed on 4--2020mA ( for host complying HART protocol ) and transmitsmA ( for host complying HART protocol ) and transmitsit to a remote location.it to a remote location.

Process

Variable

Measurement

Remote Location


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Process Variables:Process Variables: The variables which are toThe variables which are to

be monitored & controlled in a process industrybe monitored & controlled in a process industry

primarily include:primarily include:

PressurePressure

FlowFlow

LevelLevel

TemperatureTemperature


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OBJECTIVE ToUnderstand :

The need for Transmitters & Principles of Operation

The General Requirements for Transmitters

Specific Requirements for Pres.& Diff Pres Transmitters (SECL/EIL)

Transmitter Accessories

SelectionC

riterion for Pressure Transmitters Salient features of Emerson 3051S Series Transmitters

General considerations for Handling & Transportation

of Transmitters


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Why do weneed Transmitters ?

As an integral part ofCentralized Process Monitoring &

Control :

Optimized Process Performance

Aids in Generation of MIS Reports


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PRINCIPLES OFOPERATION

Measurement of Pressure

Measurement of Flow Measurement of Level

BASIC PROCESS

VARIABLE FOR


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Pressure measurement techniques widely employed are :

Capacitance Type

Strain Gauge Type

Piezoelectric Type

Differential Transformer Type


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PRINCIPLES OFOPERATIONCAPACITANCE TYPE :


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PRINCIPLES OFOPERATIONCAPACITANCE TYPE


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PRINCIPLES OFOPERATION STRAIN GAUGE TYPE :

The metallic strain gauge consists of a very fine wire or,

more commonly, metallic foil arranged in a grid pattern.

The grid pattern maximizes the amount of metallic wireor foil subject to strain in the parallel direction. The grid is

bonded to a thin backing, called the carrier, which is

attached directly to the test specimen. Therefore, the

strain experienced by the test specimen is transferred

directly to the strain gauge, which responds with a linear

change in electrical resistance. Strain gauges are

available commercially with nominal resistance values

from 30 to 3000 , with 120, 350, and 1000 being the

most common value


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Piezoelectricity is an Electric Voltage produced by

certainc

rystals and by a numbe

rofce

ramicmate

rialswhenthey aresubjectedto pressure .

This property can beuseful inmeasurementofStatic

pressure.

PIEZOELECTRIC TYPE:


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SiliconResonant SensorTechnologySiliconResonant SensorTechnology

Silicon resonant sensors are fabricated from a singleSilicon resonant sensors are fabricated from a single

crystal silicon. As pressure is applied, the bridges arecrystal silicon. As pressure is applied, the bridges aresimultaneously stressed, one in compression and one insimultaneously stressed, one in compression and one intension. The resulting change in resonant frequencytension. The resulting change in resonant frequencyproduces a high differential output (kHz) directlyproduces a high differential output (kHz) directlyproportional to the applied pressure. This simple timeproportional to the applied pressure. This simple time--

based function is managed by a microprocessor.based function is managed by a microprocessor.MicroMicro--machined from a single silicone crystal to providemachined from a single silicone crystal to provide

superior stability and repeatability while eliminatingsuperior stability and repeatability while eliminating

hysteresis.hysteresis.

PRINCIPLES OFOPERATION PIEZOELECTRIC TYPE:


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Temperature effects are less than 1/10th of other siliconTemperature effects are less than 1/10th of other silicon

technologies (10 ppm/deg C), making this extremelytechnologies (10 ppm/deg C), making this extremelystable in the most demanding process applications. Thestable in the most demanding process applications. The

output produces a much higher signal to noise ratio asoutput produces a much higher signal to noise ratio as

compared to analog sensors. Errors resulting fromcompared to analog sensors. Errors resulting from

temperature and static pressure are insignificant intemperature and static pressure are insignificant in

relation to total output.relation to total output.

This advanced sensor technology is applied toThis advanced sensor technology is applied to

Yokogawa's DPharp EJX seriesYokogawa's DPharp EJX series pressurepressure transmitter.transmitter.

PRINCIPLES OFOPERATION PIEZOELECTRIC TYPE:


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General requirementsforTransmitters ?

Operating Voltage : 24 DC / 110 V 50 Hz AC

Two Wire System with 4-20 mA Standard Output with

. superimposed digital signal having simultaneous

. analog & digital communication , using HART Protocol.

LCD Display in Engineering Units and % for level in field

Mounting : 2pipe Mounted or Panel Mounted Intrinsically Safe or Ex-proof

Microprocessor based with non-volatile memory


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General requirementsforTransmitters ?

Range : Process variable is indicated within

40 to 60% for linear , 60 to 80% for square root inputs

Accuracy : +/- 0.1% of span for a rangeability of 1:100

External zero adjustment and Integral vent / drain

Tx to run complete Auto Diagnostic Routine, in event of

failure, o/p shall be driven to predefined value.

Response Time


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Specific requirements for Pressure / DP Transmitters

Pressure :

Atmospheric Pressure : Pressure on the surface of earth

due to column of air above

Gauge Pressure : Pressure above Atm. Pressure

(excluding Atm. Pressure)

Absolute Pressure : Gauge pressure + Atm. Pressure

Differential Pressure : Pressure difference across a

restriction in fluid flow path in pipe

or in a liquid column in a vessel


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Differential & Absolute PTs shall be :

316 SS Capsule Diaphragm

CS Bodies or SS 316 or Monel or Tantalum

NPT Threaded Process Connections / Flange

Connection 1/2/3 depending on the service.

DPT with Integral Manifold


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Over Range protection :

PTs : able to withstand ORP ~ 100% of max. span

DPTs: able to withstand ORP ~ body rating on either

side of the element

RFI Interference / Magnetic Interference:

+/- 0.1% of span from 20 to 1000 MHz and for field

strength upto 30 V/m.


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Transmitter Accessories

Volumetric Diaphragm Seals

Capillary Tubes

Manifolds : Coplanar Design , Traditional Design ,

Inline Design


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ACCESSORIES


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SELECTION CRITERION

Functional Specifications

Performance Specifications

Material Selection

Desirable Features


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SELECTION CRITERION

FUNCTIONAL SPECIFICATIONS

Temperature : Maximum Process & Ambient Temp.

Pressure : Operating Pressure Range & Maximum Press.;

Minimum Pressure (vacuum) ; Static line

pressure for differential transmitters,

Environment : The transmitter should be capable ofoperating in environments with 0 to 100%

relative humidity. The working fluid and the

ambient environment should be considered

for corrosiveness.


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SELECTION CRITERION

DefinitionofHazardousLocations:

Class I, Division I

Locations in which hazardous concentrations of flammable gases or

vapors exist continuously, intermittently, or periodically under normaloperating conditions.

Class I, Division II

Locations in which volatile flammable gases are handled, processed

or used, but in which the hazardous liquids, vapors or gases will

normally

be confined within closed containers or closed systems from which

they can escape only in case of accidental rupture or breakdown of

such systems or containers, or in case of abnormal operation of

Equipment.


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SELECTION CRITERION

Class II Locations

Locations which are hazardous because of the presence of combustible

dust.

Class III Locations

Locations in which easily ignitable fibers or materials producing

combustible flyings are present.

Group A

Atmospheres containing acetylene.

Group B

Atmospheres containing hydrogen or gases or vapors of equivalent

hazards such as manufactured gas.


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SELECTION CRITERION

Group C

Atmospheres containing ethyl ether vapors, ethylene, or cyclopropane.

Group D

Atmospheres containing gasoline, hexane, naptha,benzine, butane,

alcohol, benzol, lacquer solvent vapors, or natural gases.

Group E

Atmospheres containing metal dust, including aluminum, magnesium,

and their commercial alloys, and other metals of similarly hazardouscharacteristics.

Group F

Atmospheres containing carbon black coal or coke dust.


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SELECTION CRITERION

Group G

Atmospheres containing flour, starch, or grain dusts.

Explosion-ProofEnclosureExplosion-proof enclosure means an enclosure for electrical

apparatus which is capable of withstanding, without damage, an

explosion which may occur within it, of a specified gas or vapor,

and capable of preventing ignition of a specified gas or vapor

surrounding the enclosure from sparks or flames from theexplosion of the specified gas or vapor within the enclosure. To

make a system explosion-proof, the enclosure must be capable ofwithstanding an explosion.


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SEL

ECTIO

N CR

ITER

IO

NIntrinsically Safe EquipmentIntrinsically safe equipment and wiring are incapable of releasing

sufficient electrical energy under normal or abnormal conditions to cause

ignition of a specific hazardous atmospheric mixture. Abnormal conditions

will include accidental damage to any part of the equipment or wiring,

insulation, or other failure of electrical components, application of overvoltage, adjustment and maintenance operations, and other similar

conditions. Equipment built for this requirement is designed with low

energy storage components.

Several advantages to the intrinsic safety approach are listed below.These advantages have to be weighed against the initial higher purchase

price :

Lower installation cost Less operator-dependent to maintain a safe

system Easier to maintain and repair Accessible to repair without

special precautions before opening the unit


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SEL

ECTIO

N CR

ITER

IO

NPERFORMANCE SPECIFICATIONSACCURACY : Closeness to the actual value .

HYSTERISIS : Hysteresis is the maximum difference for

the same input between the upscale and

downscale output values during a full range

traverse in each direction.

REPEATIBILITY : Repeatability is the closeness of

agreement among a number of

consecutive measurements of the output

for the same value of the input under the

same operating conditions, approaching

from the same direction. It does not

include hysteresis


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SEL

ECTIO

N CR

ITER

IO

NPERFORMANCE SPECIFICATIONS

Reproducibility : Reproducibility is the closeness of

agreement among repeated measurements of the

output for the same value of input mode under thesame operating Conditions over a period of time,

approaching from both directions. Normally this

implies a long period of time. It includes hysteresis,

drift, and repeatability.


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Technical Standards for TransmittersTechnical Standards for TransmittersSELECTION CRITERION


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SEL

ECTIO

N CR

ITER

IO

N


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SEL

ECTIO

N CR

ITER

IO

NFEATURES :

Range Adjustability

External Zero Adjustment

Adjustable Damping for pulsating process conditions

Reverse Polarity Protection

Installation Considerations for greater Flexibility

Local Indications may be considered eg. for tank level

Modular Plug in Circuit Boards for easily accessible test

pts.


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Salient Features of Emerson Series 3051 S Transmitters

Power Supply Variation: 10.5 to 42.4 V DC with no load

Model No.: 3051S1CD 2 A 2 E12 A 1A B4

Diaphragm Material :

Hastelloy

Monel

Tantalum

Gold Plated Monel

Gold Plated 316L SST


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Transmitter Labels :

Information Label:

Name & Address of Manufacturer

Complete Model No.

Device Serial No.

Year ofConstruction

Marking for Explosion Protection


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Transmitter Labels :

Intrinsic Safety Housing Label

Type n Housing Label Dust Housing Label

Flame Proof Label


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Technical Standards for TransmittersTechnical Standards for TransmittersSalient Features of Emerson Series 3051 S Transmitters


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General Packaging & Handling Procedures for Transmitters :

A Permanent Tag to be attached on each Tx specifying:

Tag No,

Manufacturers Name or Trademark, Model No. or Type,

Serial No.,

Press-Temp rating,

Body & Material Element, Calibrated Span & Units,

Range Limits

Power Supply-Electrical Classification


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General Packaging & Handling Procedures for Transmitters :

Each Carton or Box to be marked with the Instrument

Tag No. on top & side of the Carton

For Larger Box containing multiple cartons the larger

box to be marked on top with all Tag Nos.

All ports & openings to be sealed, threaded connections

protected using caps or plugs.


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CONCLUSION

Provides guidelines for the Key Technical Specifications to

be followed while selecting & ordering Transmitters.

&

DISCUSSION


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Thank You !!Thank You !!

Technical Standards for Transmitters

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