Courses Outline / Training content

I. Key topics include the following areas pertaining to instrumentation and control:

•        Pressure

•        Flow

•        Level

•        Temperature

•        Control

At the end of training the participants will be able to:

Pressure

•        explain the basic working principle of pressure measuring devices: bourdon tube, bellows, diaphragm, capsule, strain gauge, capacitance capsule;

•        explain the basic operation of a differential pressure transmitter;

•        explain the effects of operating environment (pressure, temperature, humidity) on pressure detectors;

•        state the effect of the following failures or abnormalities: over-pressuring a differential pressure cell or bourdon tube; diaphragm failure in a differential pressure cell;  blocked or leaking sensing lines; and loss of loop electrical power.

Flow

•        explain how devices generate a differential pressure signal: orifice, venturi, flow nozzle, elbow, pitot tube, annubar;

•        explain how each of the following will affect the indicated flow signal from each of the above devices:
             - change in process fluid temperature;
             - change in process fluid pressure; and

                            - erosion.

•        identify the primary device, three-valve manifold and flow transmitter in a flow measurement installation;

•        state the relationship between fluid flow and output signal in a flow control loop with a square root extractor;

•        state the effect on the flow measurement in process with abnormalities: Vapour formation in the throat, clogging if throat by foreign material, Leaks in HI or LO pressure sensing lines;

Level

•        explain how a level signal is derived for: an open vessel, a closed vessel with dry reference leg, a closed vessel with wet reference leg;

•        explain how a DP cell can be damaged from over pressure if it is not isolated correctly;

•        explain how a bubbler derives level signal for an open tank;

•        explain the need for zero suppression and zero elevation in level measurement installations;

•        describe the effects of varying liquid temperature or pressure on level indication from a differential pressure transmitter;

•        explain how errors are introduced into the DP cell signal by abnormalities: leaking sensing lines, dirt or debris in the sensing lines;

Temperature

•        explain the principle of operation of temperature detectors: RTD, thermocouple,  bimetallic strip & pressure cylinders;

•        state the advantages and disadvantages of  RTDs and
thermocouples
•        state the effect on the indicated temperature for failures, open circuit and short circuit; 

Control

•        identify the controlled and manipulated variables;

•        sketch a simple block diagram and  indicate set point, measurement, error, output and disturbances;

•        state the difference between open and closed loop control;

•        explain the general on/off control operation;

•        explain why a process under on/off control is not controllable at the set point;

•        explain why on/off control is suitable for slow responding processes;

•        explain the meaning of proportional control in terms of the relationship between the error signal and the control signal;

•        explain why offset will occur in a control system, with proportional control only;

•        choose the controller action for corrective control;

•        convert values of PB in percentage to gain values and vice-versa;

•        determine the relative magnitude of offset with respect to the proportional band setting;

•        state the accepted system response, i.e., 1/4 decay curve, following a disturbance;

•        explain the reason for the use of reset (integral) control and its units;

•        sketch the open loop response curve for proportional plus reset control in response to a step disturbance;

•        state two general disadvantages of reset control with respect to overall loop stability and loop response if the control setting is incorrectly adjusted;

•        calculate the reset action in MPR or RPM given a control system‘s parameters;

•        state the purpose of rate or derivative control;

•        state the units of derivative control;

•        justify the use of rate control on slow responding processes such as heat exchangers;

•        explain why rate control is not used on fast responding processes.

•        sketch the open loop response curve for a control system with proportional plus derivative control modes;

•        state which combinations of the control modes will most likely be found in typical control schemes;

•        sketch typical control schemes for level, pressure, flow and temperature applications.

Also, the participants will know the instrument symbols, instrument abbreviations and colour coding, being able to read a P&ID and an electrical control drawing.

 

II. Other topics include:

·        INTERNATIONAL SYSTEM of UNITS (SI)

·        Basics of PFD & PID.

 

BACK [to “TRAINING” page]