Top Instrumentation and Control Engineers Interview Questions List


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Instrumentation and Control Engineers Questions and Answer

QUESTIONS BY TOPIC

PNEUMATICS:

1.EXPLAIN HOW A FLAPPER AND NOZZLE WORKS?
2. SKETCH A TYPICAL AIR SUPPLY TO AN INSTRUMENT?
3. EXPLAIN HOW A PNEUMATIC RELAY WORKS?
4. WHY DO WE HAVE A VENT HOLE AT THE BOTTOM OF A REGULATOR?
5. IF SUPPLY AIR HEADER PRESSURE FELL FROM 100 PSI TO 50 PSI, WILL THE REGULATOR OUTPUT ALSO FALL?
6. HOW DOES A LOCK UP RELAY WORKS?
7. DRAW A SKETCH OF A PNEUMATIC CONTROLLER WITH P.& I. D CONTROL?

FLOW

1.HOW TO ZERO CHECK A FLOW TRANSMITTER (ORIFICE)?
2. WHAT ARE THE TYPES OF ORIFICE PLATES?
3. WHY DO WE HAVE A SMALL HOLE, SOMETIMES ABOVE OR BELOW THE ORIFICE HOLE?
4. HOW TO TOP UP/ FILL LINES ON FILLED SYSTEM INSTALLATION?
5. ADVANTAGES/DISADVANTAGES OF ORIFICE PLATES, VENTURI TUBES ETC.
6. SIZING OF ORIFICE PLATES (ENGINEER, S.I.T ONLY)
7. SKETCH TYPICAL FLOW INSTALLATION.
8. WHY DO WE FIND A SQUARE ROOT EXTRACTOR ON FLOW LOOPS?
9. WHY ARE MAGNETIC TYPE FLOW METERS GENERALLY NOT USED IN REFINERIES?
10. RE RANGE A D.P TYPE FLOW METER (CALCULATION)

LEVEL:

1.HOW DO YOU CALIBRATE A LEVELTROL/DENSITY ADJUSTMENT?
2. HOW DO CALIBRATE AN INSTRUMENT USED ON INTERFACE SERVICE?
3. HOW DO CALIBRATE A LEVEL SWITCH (INCREASING AND DECREASING) SIGNAL?
4. ELEVATION AND SUPPRESSION KITS WHY WE USE?
5. TYPICAL OPEN AND CLOSED TANK LEVEL MEASURING SYSTEM?
6. CAPACITANCE LEVEL TYPE LEVEL MEASUREMENT, EXPLAIN.
7. TYPICAL LEVEL ALARM SETTINGS FOR HIGH (H), HIGH HIGH (HH), LOW (L), AND LOW LOW(LL)
8. ENRAF TYPE LEVEL GAUGES.
9. BUBBLE TUBE TYPE INSTALLATION
10. EFFECT OF DENSITY ON LEVEL MEASUREMENT?

PRESSURE:

1.TYPE OF PRESSURE GAUGES .
2. ABSOLUTE / GAUGE PRESSURE / DIFFERENTIAL PRESSURE.
3. ZERO ADJUSTMENT ON A PRESSURE GAUGE.
4. MEASURING VACUUM. VACUUM SCALE EXPLAIN.
5. HOW DOES A BOURDON TUBE WORKS?
6. HOW DOES A D.P CELL WORKS?
7. HOW WOULD YOU CALIBRATE A HIGH RANGE PRESSURE TRANSMITTER (0~100 H.G)

TEMPERATURE:

1.2 ,3 AND 4 WIRE R.T.D. CIRCUITS?
2. THERMOCOUPLE PRINCIPLE.
3. TYPES OF THERMOCOUPLES.
4. UPSCALE BURNOUT.
5. ABSOLUTE TEMPERATURE/ DEG.F TO DEG.C CONVERSION.
6. DIFFERENCE BETWEEN THERMOCOUPLE CABLE AND COMPENSATING CABLE.
7. FILLED SYSTEMS. SCALE READING FOR LIQUID , VAPOUR AND GAS.
8. CONNECTING OF THERMOCOUPLE LEADS TO COMPENSATING CABLE.
9. AMBIENT TEMP. COMPENSATION FOR THERMOCOUPLES.
10. AMBIENT TEMP. COMPENSATION FOR FILLED SYSTEMS.

CONTROL VALVES:

1.TYPES OF CONTROL VALVES.
2. SKETCH IN DETAIL ALL PARTS OF A VALVE.
3. WHY DO WE USE A POSITIONER?
4. WHAT IS F.O / F.C / F.L (FAIL OPEN, FAIL CLOSED, FAIL LOCKED)?
5. WHAT IS A C.V OF A VALVE?
6. ADVANTAGES, DISADVANTAGES OF DIFFERENT TYPES OF VALVES.
7. SEAT TIGHTNESS (ENGINEERS, S.I.T.S, ONLY)
8. SIZING OF CONTROL VALVES (ENGINEERS, S.I.T. ONLY)
9. HOW TO REVERSE ACTION OF A VALVE?
10. REPLACEMENT OF VALVE PACKING.
11. HOW WOULD YOU DEAL WITH A JERKY OR STICKING OF A CONTROL VALVE?

CONTROL SYSTEMS:

1.EXPLAIN P.&I.D ACTION.
2. WHERE DO WE NORMALLY USE D ACTION.
3. SKETCH CASCADE CONTROL LOOP. EXPLAIN OPERATION.
4. WHY WE USE CASCADE CONTROL?
5. EXPLAIN HOW DO YOU TUNE A CONTROL LOOP.
6. IN CASCADE CONTROL, WHICH IS MASTER, WHICH IS SLAVE?
7. WHAT IS ON-OFF CONTROL?
8. HOW TO COMMISSION A CASCADE LOOP?
9. HOW CAN INTEGRAL ACTION INTRODUCE PROBLEM?

SAFETY, HAZARDOUS AREAS:

1.EXPLAIN INTRINSIC SAFETY.
2. WHAT IS A ZENER BARRIER?
3. ZONE CLASSIFICATIONS.
4. USE OF TEST EQUIPMENT IN HAZARDOUS AREAS.
5. PURGING OF CABINETS WITH INERT GAS OR CLEAN AIR.
6. WHAT IS THE NORMAL ZONE CLASSIFICATION FOR A REFINERY.
7. USE OF WORK PERMITS(HOT AND COLD PERMITS).
8. MEANING OF EXPLOSION PROOF?

GENERAL QUESTION RELATED TO INSTRUMENTATION

1.EXPLAIN THE PRINCIPLE OF OPERATION OF AN ELECTRONIC TRANSMITTER WITH BLOCK DIAGRAM.
2. WHAT IS A HOOK - UP DIAGRAM? WHAT ARE THE DIFFERENT TYPES OF TAPPING FOR AN ORIFICE PUT IN (A) GAS ( B ) LIQUID ( C ) STEAM SERVICE EXPLAIN.
3. WHAT ARE DIFFERENT TYPES OF FLOW MEASUREMENTS/
4. EXPLAIN A TYPICAL PROCESS ( IN YOUR PLANT ) ITS AND ASSOCIATED MEASUREMENT + CONTROL. (VIZ. TANK LEVEL, AIR COMPRESSOR, ETC.).
5. WHAT IS A SIMPLE P.I.D CONTROLLER? EXPLAIN THE ACTIONS OF P.I.D.
6. EXPLAIN THE DIFFERENCE BETWEEN ALIGNMENT AND TUNING OF THE CONTROLLER?
7. EXPLAIN TUNING OF THE CONTROLLER WITH JUSTIFICATION?
8. WHAT IS A CASCADE CONTROL SYSTEM? GIVE A TYPICAL EXAMPLE AND EXPLAIN?
9. DRAW A FLOW LOOP ( CLOSED )WITH PROPER SYMBOLS? ( PNEUMATIC AND ELECTRONIC).
10. LIST DIFFERENT TYPES OF CONTROL VALVES? NAME THE PARTS OF A TYPICAL VALVE YOU ARE FAMILIAR WITH.
11. HOW YOU REDUCE CAVITATION IN THE VALVE?
12. EXPLAIN THE APPLICATION OF SINGLE SEATED AND DOUBLE SEATED VALVES WITH ITS LIMITATIONS?
13. WHAT ARE THE DIFFERENT ACCESSORIES OF A CONTROL VALVE?
14. WHAT ARE THE MATERIALS USED FOR PLUG AND SEAT WHEN THE TEMPERATURE OF THE FLUID IS HIGH AT CORROSIVE ATMOSPHERE?
15. EXPLAIN FLOW CHARACTERISTIC OF A VALVE + C.V OF VALVE.
16. WHAT ARE THE DIFFERENCE BETWEEN R. T. D. + THERMOCOUPLE? LIST DIFFERENT TYPES OF THERMOCOUPLE AND THEIR RANGES.
17. EXPLAIN THE METHOD OF CALIBRATING A LEVEL TROL IN SITE WITH WATER?
18. WHAT IS A JUNCTION BOX? EXPLAIN THE FUNCTION OF IT.
19. INTRINSIC SAFETY - EXPLAIN.
20. DRAW A CIRCUIT OF FULL WAVE RECTIFIER AND DERIVE A DUAL POWER SUPPLY.
21. WHAT ARE THE LOGIC CIRCUITS? EXPLAIN AND, OR, NOT NOR, NAND CIRCUITS USING DIODES.
22. WHAT IS A MULTIPLEXER?
23. STATE THE DIFFERENCES BETWEEN RELAY LOGIC + PROGRAMMABLE LOGIC CONTROLLER?
24. EXPLAIN THE ACTION OF AIR TO OPEN AND AIR TO CLOSE ACTION OF A CONTROL VALVE? EXPLAIN WHY.
25. EXPLAIN WITH EXAMPLE SPLIT RANGE ACTION.
26. WHAT IS AN IMPULSE LINE? ITS LIMITATIONS.
27. CONNECT A THREE WAY SOLENOID VALVE TO A CONTROL VALVE AND EXPLAIN SHUTDOWN ACTION FOR A TYPICAL PROCESS YOU ARE FAMILIAR WITH.
28. LIST THE TEST INSTRUMENTS FOR CALIBRATING 0 - 1000 PSI ELECTRONIC TRANSMITTER AND EXPLAIN THE METHOD.
29. WHAT ARE UNITS OF PRESSURE , FLOW ,TEMPERATURE ,AND CONDUCTIVITY?
30. EXPLAIN A TYPICAL PROBLEM YOU HAVE FACED IN YOUR PLANT IN RECENT TIMES + HOW DID YOU TROUBLE SHOOT IT?

GENERAL QUESTION INSTRUMENTATION - PART 2

1.DRAW A TYPICAL FLOW ,LEVEL, PRESSURE, TEMPERATURE CONTROL LOOP AND GIVE A FULL EXPLANATION.
2. NAME AS MANY PRIMARY MEASURING ELEMENTS AS YOU CAN FOR FLOW, LEVEL, PRESSURE, AND TEMPERATURE.
3. WHAT IS MEANT BY CLOSED LOOP AND OPEN LOOP CONTROL.
4. DESCRIBE THE SEQUENCE USED TO ISOLATE A D/P TRANSMITTER.
5. DESCRIBE CALIBRATION OF A D/P CELL TRANSMITTER.
6. HOW DO IDENTIFY FLOW DIRECTION THROUGH AN ORIFICE PLATE.
7. HOW DO TUNE A CONTROL LOOP.
8. DESCRIBE ( IN GRAPH FORM AND VERBALLY ) EACH OF THE 3 TERMS OF CONTROL P. , P +I , P + I +D .
9. DESCRIBE THE OPERATION OF I / P CONVERTER.
10. FUNCTIONS OF A VALVE POSITIONER.
11. SKETCH AND IDENTIFY MAJOR PARTS OF A TYPICAL CONTROL VALVE.
12. PROCEDURE OF HAVING A CONTROL VALVE ISOLATED AND REMOVED FROM THE PROCESS LINE ( NOT FORGETTING OBTAINING WORK PERMIT)
13. WHAT TO LOOK FOR AND WHAT ACTION IN THE EVENT OF CONTROL VALVE STUCK IN ……………… POSITION.
14. HOW DO WE MEASURE LEVEL?
15. HOW DO WE COMMISSION A DP CELL USED FOR LEVEL MEASUREMENT IN A CLOSED VESSEL?
16. WHAT IS A THERMOCOUPLE ------ PRINCIPLE OF OPERATION----- HOT AND COLD AND JUNCTION— EXPLAIN EXTENSION LEAD ( COMPENSATION CABLE) – TYPE OF THERMOCOUPLE AND TYPICAL TEMP. RANGE.
17. WHAT IS A RTD? EXPLAIN DIFFERENCE 2 AND 3 WIRE SYSTEM. DRAW SKETCH A TYPICAL WHEATSTONE BRIDGE A SHOWING A 3 WIRE RTD.
18. WHAT IS FOX NET? EXPLAINATION OF SYSTEM AND TIE - INST. THROUGH U.E.M. , WHAT IS MEANT BY C.C.M.? WHAT IS THE TOTAL NUMBER OF INTERSPEC STATIONS CONNECTED TO AN INTERSPEC BUS? TIE IN OF INTERSPEC TO FOX NET.
19. WHAT IS A CASCADE CONTROL SYSTEM?
20. PROCEDURE OF COMMISSIONING A CASCADE CONTROL LOOP. SHOW TYPICAL SKETCH AND APPLICATION.

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