Instrumentation

ROTC March 2016

PresenterRajiv Dhillon

Instrumentation Purpose of Instrumentation Evolution of Instrumentation Choosing the Right Instrument Installation Options Instrument Engineer’s Skill Set

Instruments Are Our EyesPrinciple measurements desired in industry: Temperature Pressure Level Flow Analytical - pH, Turbidity

Specific importance to the sugar industry: Density of sugar (Brix)

General Overview: Human beings are not well designed for process conditions. Instruments can be selected to match specific process conditions. Two main parts to an instrument:

Sensor: feels the condition of the process.

Transmitter: amplifies this signal to allow display or transmission to the control system.

Transmitter

Sensor

Functional Elements of an Instrument

Process/Measured medium

Primary Sensing ElementE.g. Level

Variable Conversion ElementDigital value

Variable Manipulation ElementScaled Value

DataTransmission Element4-20mA to PLC

Data Presentation ElementCITECT or HMI

Observer

BackgroundImportant discoveries 1592 – 1st thermometer 1701 – first practical thermometer late 1700’s – temperature is not a fluid! 1821 – thermocouple effect 1880 – first controller 1885 – effect of temperature on conductivity late 1800’s – metals have different thermal expansion effect

Background – Beginning of Industrial Revolution to ~ 1920’s

Temperature readings by a Thermometer Pressure by Bourdon Tube Gauges – still

common practice Level by Sight Glass dP by Manometer

Background – Need to Transmit Signals to Directly Control the Process1930’s Transmitters used to convert sensing

device signal to pneumatic signal Feedback controllers invented – PID Improvements in valve design to

better control process Valves fitted with pneumatic actuators

Foxboro Flow Controller w/ 24-hr. Chart Recorder

Background – Further Improvements in Signal Transmission and ControlEarly 1960’s Most process signals can be converted to low-level electric signals 4-20 mA current loop was standardized for analog devices Early computers used to control process

Background – Instrumentation Developments in the Last 20 Years Recognized weaknesses of 4-20 mA current loop

- needs continuous re-zero and re-rangetransmits PV in a scaled format only.

1988 - Digital Instrumentation with Self-calibration, Diagnostics, Messaging capability.

1998 - Networked instrumentation - Bus systems for Process Instruments.

Presently - Wireless Transmitters and Self-Organizing Networks.

Choosing the Right Instrument Instrument selection determines the success of

the entire control system (garbage in = garbage out).

Choices are vast, all with pros and cons. After selection, error can still be made in sizing,

installation and process connections.

Point Level Measurement

Vibrating ROD• Will function

even when bent!• Fine grain or

coarse grain, non-fluidised bulk solids.

Tuning Folk• Susceptible to

bridging and damage to prongs.

• Fine grain or powdery solids.

White Sugar??

Icing Sugar??

Installation Options (Mounting Locations)

Level Measurement• Hydrostatic Head • Float• Load Cells• Magnetic Level Gauge• Capacitance

Transmitters• Magnetostrictive• Ultrasonic• Microwave• Laser• Radar• Guided Wave Radar• Dip Stick• Vibration

Considerations Open tank or closed tank? Can the level sensor be inserted into the tank or should it be completely

external? Contact or non-contact? Continuous measurement or point measurement? What type of material is being measured? Liquid or Solid? Clean or Slurry? Is the tank in a Hazardous Area?

BRIX (Moisture Concentration)

Pro-M-TecPan Probe

BERTOLD100mm Flow

Tube

SMARTank Measurement

Consistency Probe (Magma)

• DC Motor armature current increases with rotor load. (viscosity)

• Constant head height supplied by weir.

• Deflection plate to reduce flow influences.

Process ConnectionsDRD Flange TRI-CLAMP®

The DRD flange is well used in food

industry. Disadvantage is

the big diameter of 125mm, which

might prevent the use in the conical

part of a tank.

Well used within the food industry

too. Easier installation.

Fieldcare

FieldCare is Endress + Hauser’s plant asset management tool we use to configure Analytical device parameters, including storage of configurations.

Calibration“Set of operations which establishes, under specified conditions, the relationship between values indicated by a measuring instrument or measuring system, and the corresponding standard or known values derived from the standard”. ANSI

OR: Comparison of one instrument’s response with that of a reference instrument of known response and accuracy.

Purpose: to establish the reliability of the instrument i.e. that it can be trusted.

CALIBRATION RECORDS

Internal Calibration Sheet External Calibration Sheet

Instrument Engineer’s Skill Set Understanding of the process and all Engineering Fundamentals Understanding of process dynamics and process response Understanding of applications of feedback control and opportunities for

advanced control Work effectively with process operators Constantly upskilling with changing technology Documentation and traceability Attention to detail

Thank You!