Instrument Queries
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Transcript of Instrument Queries
Objective type Questions
1‐Which Type of work permit is used for Grinding in the field?.
Ans‐ Hot work permit
2‐If a transmitter shows reading above normal what you will do?
Ans‐Get permit, Isolate the transmitter, purge and check Zero if problem then calibrate.
3‐ What types of Ultrasonic Flow Measurement exist in industries?
Ans‐Transient & Doppler Effect Type.
4‐Describe the function of Accumulator into the Pump?
Ans‐ Reduce the pulsating in the suction fluid of a pump.
5‐Describe the following safety code of instrument>
Ex d II C T6
Ans‐
Ex=Explosion Protection
d= Types of protection d,Dust proof
II= indicates grouping Group I=Under ground work Group II=Surface work
C=Gas sub division Group c= Hydrogen
T6=Temperature class T6=85 degree
6‐ What means by IP65?
Ans‐ IP=Ingress protection
65=Degree of protection 6=Complete protected against dust
5=Protected against Jet of water from all direction of instrument
7‐If signal fails and valve goes to close?
Ans‐FTC(fail safe to close)
8‐If signal increase and valve goes to close position
Ans‐Direct acting
9‐Which mechanical device is used in pressure gauges to reduce pulsating>
Ans‐Snubber
10‐In steam service,pressure gauge is used with?
Ans‐Siphon
11‐Main purpose of cage is?
Ans‐Reduce noise
12‐If controller signal is 50%, and valve opening is 75%, valve characteristics is
Ans‐Quick Opening
13‐If Equal percentage valve is used and valve opening is 62% what is the controller O/P
Ans‐75%
14‐Valve seat leakage class VI is
Ans‐Tight shut off
15‐If error in the controller is +2%, error in the transmitter is ‐1%, the total error is
Ans‐+1%
16‐Describe anti‐surge loop?
Ans‐To minimize/reduce or illuminate the surging effect in the compressor
17‐what effects a surging can produce in the compressor?
Ans‐a‐Bow of compressor Shaft b‐Stress on sealing’s c‐Damage internal parts .
18‐What mean by 2 out of 3 voting logic in the controller system?
Ans‐System trip when any 2 inputs variable goes to Bad state
19‐If the Feedback link disengages from the valve, what happened with valve?
Ans‐Valve goes to fail safe position either close/open
20‐If valve is opened with a momentum jerk, causes due to?
Ans‐Glands are over tight/Air supply UN sufficient
21‐What type of Serial links are used in control system normally?
Ans‐RS‐232/485
22‐Triconex used processing techniques of?
Ans‐TMR (Triple Modular Redundant)
24‐PlC has cycling speed than DCS?
Ans‐High
25‐One of the most popular method of Flow measurement is?
Ans‐DP type
26‐What LEL stands for?
Ans‐Low Explosive Limit
27‐What LTV stand for?
Ans‐Low Thresh hold Value
28‐To do job in the field, must be primary requirement is?
Ans‐PPEs(Personal Protective equipments)
29‐In Triconex system, RED LED indicates?
Ans‐Normal operation
30‐Software used in Triconex is called?
Ans‐TRI‐Station
31‐In 3500 vibration monitoring system, firmware used is called?
Ans‐RCS(Rack Configuration system)
32‐3500 monitoring system total PLC is called?
Ans‐System 1
33‐Active type speed probe needs?
Ans‐Energization power supply
34‐For minimum speed measurement, a suitable probe is?
Ans‐Active type
35‐The minimum conductance which can be measure/sensed by Mag flow meter?
Ans‐0.5micro Siemens
36‐In mountains area which type of Transmission is suitable?
Ans‐Line of Sight transmission
37‐The wave receiving by Radar Type transmitter is called?
Ans‐Echo
38‐The radar transmitter measures?
Ans‐The time factor of Echo
39‐In open Underground tank, level is measured by?
Ans‐Bubbler type transmitter
40‐Hart stands for?
Ans‐High Way Addressable Remote Transducer
41‐If a cable has 0.5 ohm/m resistance, how much a transmitter get resistance if the cable length is 100 m?
Ans‐50 ohm
42‐Key phaser is basically used for?
Ans‐phase amplitude of shaft
43‐MSDS stands for?
Ans‐Material safety data sheet
44‐Rectifiers are used to convert?
Ans‐Ac/DC voltage
45‐In Triconex, communication to the other system which card is used?
Ans‐SMM (safety manager module)
46‐On line cards are replaced in Triconex due to?
Ans‐TMR techniques
47‐EMS standard is based of
Ans‐1400‐200(Environmental management system
48‐If a transmitter is installed 10 m below its tapping point how much pressure exerted if fluid is water?
Ans‐4.3mH2O
49‐In 3‐Element loops what is the master variable?
Ans‐Level
50‐3‐element is used to illuminate the effect of?
Ans‐Swelling/Shrinking
51‐In‐3 element loop if we want to calibrate the transmitter we should keep controller on?
Ans‐ Single loop
55‐In Gas turbine IGV stands for?
Ans‐Inlet gide Vanes
56‐IGV is used to control
Ans‐Speed of turbine
57‐In ISO mod of gas turbine operation?
Ans‐Load remains constant
58‐In Droop mode of GT,which remains constant?
Ans‐Speed constant.
59‐In boiler which Gas is used for Purging?
Ans‐Nitrogen
60‐What is NFPA Stands for?
Ans‐National Fire Protection Association
61‐In NFPA Diamond Blue Color shows?
Ans‐Health Hazard
62‐Which type of Fire extinguisher is used in Electric type fire?
Ans‐Co2
63‐K type thermocouple temperature range is?
Ans‐0‐‐‐1600Deg
64‐If DP is 25% what is volumetric flow rate?
Ans‐50%
65‐To convert DP transmitter O/P to a linear range is used?
Ans‐Square Root Extractor
66‐Explain the procedure of a PT calibration
Ans‐Do your Self.
67‐If a metallic object comes near to the probe the return energy?
Ans‐Reduce
68‐ To extinguish fire with water Process is called?
Ans‐Quenching method
69‐To purge an ammonia fluid transmitter ensure on high priority?
Ans‐Wind Direction
70‐Decode the following vibration probe No
330101‐00‐24‐02‐01
Ans‐330101=8mm UNF probe 00=unthreaded length 0 24=2.4inch probe length 02=Miniature male Coaxial connector 01=Agency approval 01(CSA)
71‐What is meant by REBAM vibration probe?
Ans‐Rolling Element Bearing Activity Monitoring
72‐Enlist the probe Tip materials?
Ans‐Teflon,PPS,Ceramic
73‐If we used 330101‐00‐050‐00‐05 what is probe length?
Ans‐50cm
74‐NSV type probe stands for?
Ans‐Narrow side view
75‐In DCS system a single task is performed by?
Ans‐Multiple Controllers
76‐If signal goes to increase, valve stem goes down and valve plug will open, what is valve action?
Ans‐Air to close
76‐If signal decrease, valve stem goes down, valve plug goes to close?
Ans‐Air to Open
77‐In orifice Plate reduces stream size?
Ans‐Abruptly
78‐An orifice that is semicircular in shape rather than round, is called?
Ans‐Segmental‐bore orifice
79‐A manometer is relatively free from error because it has no?
Ans‐Moving parts
80‐The maximum recommended distance between an orifice and a manometer is?
Ans‐50 Ft
Subjective Questions
1‐How to check electrical health of Vibration probe?
2‐How you realize/select which vibration probe is able to use?
3‐Draw the schematic/functional block diagram of Triconex showing comprehensive card detail?
4‐Define Surging/Anti surging System of a compressor?
5‐Explain with the sketch of Anti surging loop of Compressor?
6‐Which transmitter is used for direct level control Measurement?
7‐Describe 3500Vibration Monitoring system?
8‐What is meant by FSK‐Hart protocol?
9‐How does a positioned work?
10‐If a valve is hunting, what you will do?
11‐How to calibrate a temperature transmitter & how a Cold junction Compensation will be carried out?
12‐How Proximitor works?
13‐Describe/Draw Mark V/VI functional detail?
14‐Do you like to perform work as a Team Work or preferred to do work as a Single?
15‐What safety precautions you will adopt to work on Steam service control valve?
16‐What is Preventive Maintenance Program (PMP) and how it is Effective in a technical/operational organization?
17‐What is procedure to work in your present organization?
18‐Why it needs to do Preventive maintenance (PM)?
19‐What is ERP program?
20‐If Company select you what is your notice period?
Multiple Questionnaires
21‐ Which one of the following combination of measured variable and its unit is wrong?
a) Pressure‐Bar b) Flow‐ Kg/hr c) Temperature‐Kpa d) Level‐%
22‐Which of the following combination is wrong for thermal elements
a) K‐Type Iron ‐Constant b) J Type Iron ‐Constant c) T Type Copper ‐Constant d) E Type Chromel –Constant
23 If polarity of thermocouple is reversed,
a) The temperature indication will not be affected b) The indicated temperature will be more c) The indicated temperature will be less d) The temperature indication will increase slowly and saturate at maximum scale range
24‐which of the following meters does not use an obstruction in the line
a) Magnetic flow meter b) Head meter c) Turbine flow meter d) Open channel meter 25 The Corlious effect associated with a) Magnetic flow meter b) Mass flow meter c) Orifice flow meter d) Venture flow meter
26 choose the correct definition of mass flow a) Mass flow =Volumetric Flow/Density of Medium b) Mass flow =Volumetric Flow X Density of Medium c) Mass flow =Volumetric Flow X Cross sectional area of Pipe
d) Mass flow =Volumetric Flow 27 which of the following principle is used in ultrasonic flow mete a) Doppler Method b) Transit time method c) Faraday ,S law of electromagnetic induction d) Both a & b 28 A pressure transmitter can also be used as a) I/P convertor b) P/I Convertor c) Position Transmitter d) None of the above 29 A DP type flow transmitter has been calibrated at 200”of WG for 2000 KG/hr range. It is required to change the range to 4000 kg/hr.What will be the new DP Setting? a) 400” WG b) 200” WG c) 800” WG d) 600” WG
30 A tank of 20m height is filled with 10 meters of Water and 10 meters of Oil. Density of Oil is 0.9. The resultant head pressure at the bottom wall of the tank is
a) 15 m b) 14.5 m c) 19 m d) 10m e) 19.1m f) 15.2m 31 An air failure: Close: globe valve fails to close completely on Air failure. What will be the probable cause? a) The spring is weak/Broken b) The diaphragm is punctured c) Instrument Air supply pressure is not enough as per bench set requirement.
d) Instrument Air supply is very high as bench set requirement
32 Which of the following leakage class of control valve are the lowest shut‐off characteristics? a) Class I b) Class II c) Class III d) Class VI e) Class IV
33 The following characteristics of Control valve: Equal increment of travel yield equal increments of flow constant pressure drop” refers to a) Quick Opening b) Parabolic c) Equal percentage d) Linear e) Fast opening f) None of them 34 what will happen if the feedback link of the control valve has failed during operation a) valve will be locked b) Will be hunting c) Will seems no problem in operation d) Positioned output will go to maximum on one direction depend upon positioned action
35 when proportional band is 100%,the gain of the automatic controller will be a) 5 b) 0.5 c) 50 d) 1 36 If PID controller has no action of integral, what will be happen a) The controller will tends to vibrate
b) The controller has steady offset from set point c) Controller will be more noise sensitive d) Action will be slow of controller 37 Which control philosophy works to measure the disturbance and correct them before they cause upset to the controlled variable? a) Feed forward control loop b) Feed back control loop c) Open loop d) Cascade loop 38 the calibration errors noticed on various components of a pressure loop are pressure Transmitter=1%” Controller Error=2%” Control valve=‐2%.What will the total resultant error? a) 3% b) 9% c) 5% d) 2.3% 39 In safe area classification :an area where explosive gas‐air mixture is continuously present: is called a) Zone 1 b) Zone 0 c) Zone 3 d) Zone 2
40 An instrument with following certification: EX d e m IIC T4” can be installed in which zone? a) Zone 0 b) Zone 1 c) Both b & c above 41 Which of the following frequencies contributes harmonics in a power line operating at 50 Hz frequency a) 100. 150,200, 250‐‐‐‐‐‐ b) 51, 52, 53, 54‐‐‐‐‐‐‐‐ c) 60, 120, 180, 240‐‐‐‐ d) None of the above 42 To avoid Ground loop current in a two wire system which of the following practice is recommended? a) Ground the shield wire at one end( either at marshaling cabinet or transmitter end)
b) Ground the shield wire at both ends( transmitter & marshaling end)
c) Connect the negative power line to the shield d) None b& c 43 which is the purpose of key phasor in compressor a) To monitor axial displacement of the compressor shaft b) For speed control of the compressor c) To monitor speed of the machine and used in condition monitoring analysis
d) To measure the vibration of the compressor shaft
44 A BNC 3120 proximitor,driving BNC 300‐00‐00‐08‐18‐02 probe will require how much feet of extension cable a) 18 feet b) 20 feet c) 17 feet d) 8 feet 45 In a TMR Triconex system with hot spare DO card installed, which of the following steps is not recommended? a) Removal of non‐active DO card b) Removal of active DO card c) On line down loading of changes d) Forcing of an input 46 what is “Sequence of events” functionality in a DCS/PLS a) It is program for sequence control of process b) It is batch control process program c) It is recording of all digital events with time resolution same as the plc scan time program
d) All the above 47 Using of the following modules.Tri station can be connected to Tricon Module? a) SMM b) EICM c) NCM
d) Both b &C 48 Error detection that is typically used on Ethernet and most local area networks is a) Checksum b) CRC(Cyclic reduncy code) c) Parity check d) None of the above 49 To connect field transmitter, which frequency is used for wireless instruments? a) 2.4 GHz b) 2.0 GHz c) 2.4 MHz d) Both a & c 50 What is meant by 2 out of 3 voting in instrument trip system? a) Any 2 instrument give trip value, system goes to trip b) Any 3 values jointly give trip, system will initiate trip c) Any single trip value will trip system d) Both a& b e) Both b & c 51 In PLC feature that indicates which alarm has operated first is called as a) SOE b) Trip history c) Both b & C
d) First out 52 To do job in a confined space vessel, one need to a) Work permit b) Entry permit & Work permit c) JSA,vessel entry and Work permit d) Both B & C 53 What steps should be taken to calibrate DP flow transmitter in Steam application while plant is in running format a) Work Permit, LP valve isolation, Equalize 3 way manifold, LP valve isolation. Depressurize the impulse line, start calibration
b) Work Permit, LP valve isolation, Equalize 3 way manifold, LP valve isolation. Depressurize impulse line, start calibration
c) Work permit, equalize 3 way manifold,LP valve isolation,LP valve isolation, depressurize impulse line, start calibration
d) Hp valve isolation, Equalize 3 way manifold,LP vale isolation, Depressurize impulse line, Work permit, Start calibration
54 The most important goal of :Continuity check” before powering up of field instrument to ensure a) Transmitter power is available b) Transmitter is wired to the proper controller loop
c) Correct transmitter is installed d) None of the above 55 which one of the following standards refer to Environmental management system a) ISO 9002 b) ISO 14001 c) ISO 9001 d) OHSAS 18001 56 A P & ID need to be updated when: a) A preventive maintenance activity is performed on a process equipment
b) A corrective maintenance activity is performed on instrument
c) A new process equipment is installed and commissioned d) Both a & b 57 To minimize electrical interference when AC power and DC wiring meet in a control panel, It is good to, a) Use a different size wire b) 90 Degree Cross the both wire c) Run the wire parallel to each other d) Twisting AC wire across the DC wire 58 A DP type transmitter is mounted 3 Feet below the Zero level in a tank, for correct value of the transmitter, its output must be; a) Zero elevated
b) Calibrated for Span c) Calibrated for true zero d) Suppressed Zero concept 59 What is the resistance of 1000 ft of copper wire( Specific resistance=10.37) given a cross‐sectional area of 10370Cmill and a wire temperature is 20 degree a) 1 ohm b) 2 Ohm c) 10 ohm d) 100 Ohm 60 what is the Standard Color code for K type thermocouple in the USA standard
a) White (+), Red (‐)
b) Purple(+), Red(‐) c) Yellow(+), Red(‐) d) Blue(+), Red(‐)
62. Which of the following is not true of thermocouples?
a. They do not use a reference junction.
b. They generate a small voltage.
c. They are composed of dissimilar metals.
d). They can be calibrated.
63. To calibrate a pressure transmitter, with a range of 0 psi to 600 psi, to .02% of
Reading accuracy, which of the following test equipment would be best suited for the calibration?
a. Precision dial gage.
b. Precision dead weight tester.
c. High pressure mercury manometer.
d. Precision air piston
64. There is a problem with our HART475 it is not communicating with smart devices error becomes "NO DEVICE FOUND"we have insert 250ohm resistance as per requirement but invain plz tell me the solution
65. On liquid service if PT Head is 18 meters. How much pressure will be exerted on it. If Transmitter is not in service?
66. If an Instrument has 550 ohm internal resistance and the cable used for that instrument is 0.5 ohm
per meter resistance. If the voltage is 12volt.How much length cable can be used?
66. how the flow rate is measured from a pipe with the help of pressure?
67. What is transducer?
68. what would be the minimum flow rate that we can measure on rotameter..?
69. what is temperature compensation?
70. Can we install leveltrol in steam drum for measurement the level of steam drum? if not then why?
71. What is the principle of ultrasonic flow meter and radar type flow meter?
72. What is modbus & what signals are taken through it
73. How to check earthing,what is minum ohms for proper earthing?
74. Explain about signal isolator?
75. What is mean by trim?
76. for crude oil application in floating roof tank, how to calibrate a DP Transmitter? How is the floating roof weight considered?
77. Working principle capacitance type level transmitter?
78. What is procedure to change mmwc into tph?
79. How can I make calculation for Install level transmitter (DP) for open tank and cloes tank?
80. How to calibration a control valve?
81. What is Dry Leg calibration and where is it used?
82. How to measure flow with DP?
83. What is coriolis principle for mass flow meter?
84. How to trim the pressure transmitter?
85. How to calibrate bubbler type level transmitter of Rosemount make and how to set air flow
according to the range... Give one calibration procedure with one example?
86. Describe flow nozzle principle?
87. What are the characteristics of control valve?
88. What is the reason for flow fluctuations happen on differential flow transmitter during in service?
89. How to calibrate the interface leveltrol?
90. What do u mean by 2/3 solenoid valves?
91. Explain about SOURCING & SINKING concepts in PLC to field sensor wiring?
92. What is sil (safety integrity level?
93. Where & why we are using SURGE PROTECTION?
94. Why using 4‐20ma not using 0‐20or why not using 1‐ 20ma?
95. Define the terms Accuracy, precision, Spam, process tolerance while doing calibration of an instrument? Explain with an example?
96. How do you calibrate the vacuum transmitter if it shows more reading?
97. How to calculate the total flow in square root?
98. What is the right procedure for adjusting the gap voltage of Bentley Nevada vibration sensor?
99. Whether radar level transmitter is applicable for the open tank?
100. What is load line in control valve?
101. What is Field bus?
102. How to overhaul control valves. What are the proper procedures?
103. How to find out turn down ratio of Pressure transmitter?
104. Why we set ‐10 volt in vibration sensor output, why not +10 volt?