Wednesday, August 23, 2017

Engineering Definations


Definitions – Instrumentation (As per Standards)-
Although I never believe in memorizing the definitions but some of the interviewers believe that if a young engineer is more found of mesmerizing the things rather than understand the things, the person is more suitable to them. This is not good for developing the engineering but for getting the job , It would be good if you try to mesmerizing few things. I am presenting it in a tabular form (Total 121)
Use ctrl F for search any particular definition if you don't want to read all, these definitions are taken from various sources as mentioned in last column.

1
ABSOLUTE CRITICAL PRESSURE
The equilibrium pressure of a fluid that is at its critical temperature, expressed in absolute units.
 
2
ABSOLUTE VAPOUR PRESSURE
The pressure, at the coincidental fluid temperature, at which the liquid is in equilibrium with its vapor.
 
3
ACCURACY RATING
A number or quantity that defines a limit that errors will not exceed when a device is used under specified operating conditions. When operating conditions are not specified, reference operating conditions shall be assumed.
ISA DICTIONARY 3RD EDITION
4
ACTUATOR
1. A pneumatic, hydraulic, or electrically powered device which supplies force and motion to open or close a valve.
2. A part of the final control element that translates the control signal into action of the final control device in the process.
ISA-dS75.05
5
AIR CONSUMPTION
The maximum rate at which air is consumed by a device within its operating range during steady-state signal conditions. It is usually expressed in ft3 / min or m3 / h at a standard (or Normal) specified temperature and pressure.
ISA DICTIONARY 3RD EDITION
6
AIR FILTER
A device for removing solid particles such as dust or pollen from a stream of air, especially by causing the air stream to pass through layered porous material such as cloth, paper or screening.
ISA DICTIONARY 3RD EDITION
7
AIR SET
A device (regulator) which is used to control the supply pressure to the valve actuator and its auxiliaries.
ISA
DICTONARY,
Ver 1.0.
8
AMBIENT
PRESSURE
The pressure of the medium surrounding a device.
ISA DICTIONARY 3RD EDITION
9
AMBIENT
TEMPERATURE
The temperature of the air surrounding a particular location.
ISA DICTIONARY 3RD EDITION
10
ANALOG
Pertaining to data in the form of continuously variable physical quantities. Contrast with digital.
ISA DICTIONARY 3RD EDITION
11
ANSI THERMOCOUPLE TYPE
The ANSI/MC96.1 Standard’s thermocouples type letter designation.
B – Platinum – 30% Rhodium vs. Platinum – 6%
E – Chromel vs. Constantan
J – Iron vs. Constantan
K – Chromel vs. Alumel
R – Platinum – 13% Rhodium vs. Platinum
S – Platinum vs. Rhodium
ANSI / MC96.1-1982
12
ASSEMBLY
A unit constructed of many parts or components, and which functions in service as a single device, mechanism or structure.
ISA DICTIONARY 3RD EDITION
13
ATMOSPHERIC PRESSURE
The barometric reading of pressure exerted by the atmosphere. At sea level 14.7 lbf/in2 or 29.92 inHg.
ISA DICTIONARY 3RD EDITION
14
BACK PRESSURE
1. The absolute pressure level as measured four pipe-diameters downstream from the turbine flow meter under operating conditions, expressed in Pascal's, [RP31.1]
2. The pressure that exist at the outlet of a pressure relief device as a result of the pressure.
ISA DICTIONARY 3RD EDITION
15
BAROMETRIC PRESSURE
Atmospheric pressure as determined by a barometer usually expressed in inches of mercury.
ISA DICTIONARY 3RD EDITION
16
BENCH SET
The calibration of the actuator spring range of a control valve, to account for the in-service process forces.
ISA DICTIONARY 3RD EDITION
17
BETA RATIO
The ratio of the diameter of the constriction to the pipe diameter.
ISA DICTIONARY 3RD EDITION
18
BLOWDOWN
The difference between the set pressure and the closing pressure of a pressure relief valve, expressed as a percentage of the set pressure or in pressure units.
API 520 Part1
19
BUBBLE POINT
The temperature at which a liquid mixture begins to boil and evolve vapors.
ISA DICTIONARY 3RD EDITION
20
CALIBRATE
To ascertain outputs of a device corresponding to a service of values of the quantity which the device is to measure, receive, or transmit. Data so obtained are used to determine the location at which scale graduations are to be placed.
ISA DICTIONARY 3RD EDITION
21
CALIBRATOR
A single or multi-purpose device or equipment, fixed or portable, which permits accurate signal generation and/or signal readout as required for the calibration of equipment.
IEC902-1987
22
CAPACITIVE INSTRUMENT
A measuring device whose output signal is developed by varying the capacitive reactance of a sensitive element.
ISA DICTIONARY 3RD EDITION
23
CAPILLARY
A tube with a very small diameter.
ISA DICTIONARY 3RD EDITION
24
CASE
An enclosure designed to hold one or more components in a fixed position, usually by nesting into a conforming recess or resting on fixed supports, in some instances, components are attached directly to the enclosure, the entire unit may be kept in storage.
ISA DICTIONARY 3RD EDITION
25
COMPRESSIBILITY FACTOR
A factor used to compensate for deviation from the laws of perfect gases. If the gas laws are used to compute the specific weight of a gas, the computed value must be adjusted by the compressibility factor Z to obtain the true specific weight.
ISA DICTIONARY 3RD EDITION
26
CONDUCTIVITY
The amount of heat (Btu) transmitted in one hour through one square foot of a homogeneous material 1 in. thick for a difference in temperature of 1 deg F between the two surfaces of the material.
ISA DICTIONARY 3RD EDITION
27
CONTROL ACTION
Of a controller or a controlling system, the nature of the change of the output effected by the input. The output may be a signal or the value of a manipulated variable.
ISA DICTIONARY 3RD EDITION
28
CORIOLIS-TYPE MASS METER
An instrument for measuring mass flow rate by determining the torque form redial acceleration of the fluid.
ISA DICTIONARY 3RD EDITION
29
CRITICAL POINT
The temperature and pressure at which the two phases of a substance in equilibrium with each other become identical, forming one phase.
ISA DICTIONARY 3RD EDITION
30
CRITICAL PRESSURE
The equilibrium pressure of a fluid that is at its critical temperature.
ISA DICTIONARY 3RD EDITION
31
CRITICAL TEMPERATURE
The temperature of a fluid above which the fluid cannot be liquefied by pressure alone.
ISA DICTIONARY 3RD EDITION
32
DEAD BAND
The range through which an input signal may be varied, upon reversal of direction, without initiating an observable change in output signal. Dead band is usually expressed in percent of span.
ISA DICTIONARY 3RD EDITION
33
DENSITY
 A physical property of materials measured as mass per unit volume.
ISA DICTIONARY 3RD EDITION
34
DESIGN PRESSURE
The maximum allowable working pressure permitted under the rule of ASME construction code.
ISA DICTIONARY 3RD EDITION
35
DESIGN TEMPERATURE
The maximum temperature at which a device is operable in the most severe condition.
 
36
DEW POINT
1. The temperature, referred to a specific pressure, at which water vapors condensate.
2. That temperature at which condensation of moisture from the vapor phase begins.
ISA DICTIONARY 3RD EDITION
37
DIAPHRAGM
 A thin, flexible disc that is supported around the edges and whose center is allowed to move in a direction perpendicular to the plane of the disc, it is used for a wide variety of purposes.
ISA DICTIONARY 3RD EDITION
38
DIAPHRAM SEAL
A thin flexible sheet of material clamped between two body halves to form a physical barrier between the instrument and process fluid.
ISA DICTIONARY 3RD EDITION
39
DIFFERENTIAL PRESSURE
1. The difference in pressure between two points of measurement.
2.  The difference in pressure between two points of  as system.
3.  The static pressure difference generated by the primary device when there is no difference in elevation between the ups.
ISA DICTIONARY 3RD EDITION
40
ENCLOSURE
A surrounding case constructed to provide a degree of protection to personnel against incidental contact with the enclosed equipment and to provide a degree of protection to the enclosed equipment against specified environmental conditions.
NEMA  250-1979
41
END CONNECTION TYPE
The configuration provided to make a pressure tight joint with the pipe. Typical categories include Flanged, Flangeless, Split Clamp, Threaded and Welded.
MODIFIED ISA
42
FACE-TO-FACE DIMESION
1. The dimension from face of the inlet opening to the face of the outlet opening of a valve or fitting. Also referred to as ``end to end’’ dimension.
2.  By extension, the dimension from face of the inlet opening to the face of the outlet opening of an in
ISA DICTIONARY 3RD EDITOIN
43
FAIL MODE
The operating mode of the tagged item should its pneumatic supply source fail (loss of supply of power).
 
44
FAIL SAFE VALUE
The outlet value of a control device which will take effect should a failure event signal the need to switch to the fail safe value.
 
45
FINAL CONTROL ELEMENT
An instrument that takes action to adjust the manipulated variable in a process. This action moves the value of the controlled variable back towards the set point.
 
46
FLAMEPROOF
A type of protection of electrical apparatus in which an enclosure will withstand an internal explosion of a flammable mixture which has penetrated into the interior, without suffering damage and without causing ignition, through any joints.
ISA dS 12.1.01
47
FLOW RATE
The quantity of fluid which moves through a pipe or channel within a given period of time.
ISA DICTIONARY 3RD EDITION
48
FRQUENCY
The number  of cycles a periodic variable passes through per unit time.
 
49
GAUGE DIAPHRAGM
An elastic element in the form of a single flat or convoluted plate that deforms to provide displacement in response to a change in pressure differential across it.
 
50
GAUGE INTERNAL STOP
A stop designed to restrain the pressure element motion by acting directly on it or on the movement mechanism.
 
51
GAUGE LIQUID FILLED CASE
A case that is filled with liquid such as glycerin or silicon fluid to at least 75% of its internal volume. Liquid filled cases may be either open front or solid front types. The purpose of this construction is to protect the internals from damage cause.
 
52
GAUGE MOUNTING
The means by which the gauge is installed or supported, typically flush mounted, stem mounted or  surface (wall) mounted.
 
53
GAUGE NOMINAL SIZE
The inside diameter of the case, normally in inches, at the dial.
 
54
GAUGE POINTER
The gauge component that, in conjunction with the dial, indicates measure value.
ASME B40.1 91
55
GAUGE POINTER ADJUSTMENT
A means of causing a change in indication. The change in approximately equal over the entire scale.
 
56
GAUGE RING
The gauge component that secures the window to the case. Ring configurations will vary for design and aesthetic reasons.
 
57
HERTZ
Unit for frequency of a periodic phenomenon measured in cycles per second.
ISA DICTIONARY 3RD EDITION
58
HYDROSTATIC TEST
Determining the burst resistance or leak tightness of a fluid component or system by imposing internal pressure.
ISA DICTIONARY 3RD EDITION
59
IMPEDENCE
The complex ratio of a force like parameter to a related velocity-like parameter – for instance, force to velocity, pressure volume velocity, electric voltage to current, temperature to heat flow, or electric field strength to magnetic field strength.
 
60
 INSERTION LENGTH
The length from the free end to, but not including, the external threads or other means of attachment, and is assigned the symbol ``U’’.
ANSI/MC96.1-1982
61
LAGGING EXTENSION LENGTH
That portion of a thermowell above the threads, intended to extend through the lagging. The length is from the lower end of the external threads of the well to the outer end of the portion intended to extend through the lagging, less one inch allowance.
ANSI / MC96.1-1982
62
LEVEL DISPLACER / FLOAT
The displacer element is usually of cylindrical shape, of a length to correspond to the level variation expected, and weighted to sink in the liquid being measured.
CONSIDINE, HANDBOOK 3RD EDITION.
63
LIQUID DENSITY
The physical property of the liquid phase measured as mass per unit volume, at the coincident pressure and temperature conditions.
 
64
LIQUID MASS FLOW RATE
The mass flow rate of the liquid phase of the stream, at the coincident pressure and temperature conditions.
 
65
LIQUID VISCOSITY
The physical property of the liquid phase measured as the internal friction of a fluid or its resistance to flow, at the coincident pressure and temperature conditions.
 
66
LOAD CELL
A transducer for the measurement of force or weight. Action is based on strain gauges mounted within the cell on a force beam.
ISA DICTIONARY 3RD EDITION
67
LOWER RANGE – VALUE
The lowest value of the measured variable that a device is adjusted to measure or indicate.
ISA DICTIONARY 3RD EDITION
68
MAGNETIC FLOWMETER
A transducer which measures the mean velocity of an electro-conducting fluid in a non-magnetic tube. The velocity is determined by measuring the electromotive force produced at two electrodes perpendicular to the axis of flow.
IEC902-1987
69
MANIFOLD (INSTRUMENTATION)
Any configuration of values which can be manipulated to create zero differential pressure at the measuring instrument.
ISA DICTIONARY 3RD EDITION
70
MASS FLOWMETER
An instrument for measuring the rate of flow in a pipe, duct or channel in terms of mass per unit time.
ISA DICTIONARY 3RD EDITION
71
MEASURED VARIABLE
The quantity, property, or condition which is to be measured.
ISA DICTIONARY 3RD EDITION
72
MELTING POINT
The temperature at which a solid substance becomes liquid; for pure substances & some mixtures it is a single unique temperature; for impure substances, solutions and most mixtures it is a temperature range.
ISA DICTIONARY 3RD EDITION
73
METER RUN
A flowmeter installed & calibrated in a section of pipe having adequate upstream & downstream length to satisfy standards of flowmeter installation.
ISA DICTIONARY 3RD EDITION
74
MIN LOAD CAPABILITY
The minimum load resistance capability rating is identified with a transmitter operating at 20mA output, with respect to a stated power voltage & rated in Ohms.
ISA-S50.1
75
NACE STANDARD
National Association of Corrosion Engineering standard
 
76
NEMA STANDARD
Consensus standards for electrical equipment approved by the majority of the members of the National Electrical Manufacturers Association.
ISA DICTIONARY 3RD EDITION
77
NIPPLE
A short piece of pipe or tube, usually with an external thread at each ends.
 
78
NORMALLY CLOSE
1.       A switch position where the usual arrangement of contacts permits the flow of electricity in the circuit.
2.       In a solenoid valve, an arrangement whereby the disk or plug is seated when the solenoid is deenergized.
ISA DICTIONARY 3RD EDITION
79
NORMALLY OPEN
1.       A switch position where the usual arrangement of contacts provides an open circuit (no current flowing).
2.       In a solenoid valve, an arrangement whereby the disk or plug is seated when the solenoid is energized.
ISA DICTIONARY 3RD EDITION
80
OUTPUT SIGNAL
A signal delivered by a device, element or system.
ISA DICTIONARY 3RD EDITION
81
OVERRANGE LIMIT
The maximum input that can be applied to a device without causing damage or permanent change in performance.
ISA DICTIONARY 3RD EDITION
82
PERMANENT PRESSURE DROP
The unrecoverable reduction in pressure that occurs when a fluid passes through a nozzle, orifice or other throttling device.
ISA DICTIONARY 3RD EDITION
83
POSITION TRANSMITTER
A device that is mechanically connected to the valve stem or shaft & generates & transmits a pneumatic or electrical signal representing the valve position. 
ISA-dS75.05
84
POSITIONER
A position controller, which is mechanically connected to a moving part of a final control elements or its actuator, & automatically adjusts its output pressure to the actuator in order to maintain a desired position that bears a predetermined relationship.
ISA-dS75.05
85
POSITIVE DISPLACEMENT METER
 A device introduce into a closed conduit consisting of enclosures of known volume & a mechanism driven by the pressure of the fluid flow whereby these enclosures are repetitively filled & emptied of fluid.
IEC902-1987
86
POSITIVE-DISPLACEMENT FLOWMETER
Any of several flowmeter designs in which volumetric flow through the meter is broken up into discrete elements & the flow rate is determined from the number of discrete elements that pass through the meter per unit time.
ISA DICTIONARY 3RD EDITION
87
POWER CONSUMPTION
The maximum amount of electrical power used by a device during normal steady-state operation.
ISA DICTIONARY 3RD EDITION
88
PRESSURE
Measure of applied force compared with the area over which the force is exerted
ISA DICTIONARY 3RD EDITION
89
PRESSURE SWITCH
A device that activates or deactivates an electrical circuit when a preselected pressure is exceeded in a process vessel or piping system.
ISA DICTIONARY 3RD EDITION
90
PROTECTING TUBE
A closed-end tube that surrounds the measuring junction of a thermocouple & protects it from physical damage, corrosion or thermo-chemical interaction with the medium whose temperature is being measured. Also known as thermowell.
ISA DICTIONARY 3RD EDITION
91
PROXIMITY SWITCH
A device that senses the presence or absence of an object without physical contact & activates or deactivates an electrical circuit as a result.
ISA DICTIONARY
92
RANGE
The set of values over which measurements can be made without changing the instrument’s sensitivity. The extent of a measuring, indicating or recording scale. The set of values that a quantity or function may assume.
ISA DICTIONARY 3RD EDITION
93
RANGEABILITY
The ratio of the maximum flow rate to the minimum flow rate of a meter.
ISA DICTIONARY 3RD EDITION
94
RATIO OF SPECIF HEAT CAPACITY
Specific heat at constant pressure divided by specific heat at constant volume.
 
95
RATIO OF SPECIFIC HEATS
Specific heat at constant pressure divided by specific heat at constant volume.
ISA DICTIONARY 3RD EDITION
96
REGULARTOR
A device for controlling pressure or flow in a process.
ISA DICTIONARY 3RD EDITION
97
REPEATABILITY
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, for full-range traverses. It does not include hysteresis.
ISA DICTIONARY 3RD EDITION
98
RESET
  1. To restore a storage device to a prescribed initial state, not necessarily that denoting zero.
  2. The sequence action that returns the sequence to the “normal” state.
ISA DICTIONARY 3RD EDITION
99
ROTAMETER
A variable-area, constant-head, indicating type rate-of-flow volume meter in which fluid flows up through a tapered tube, lifting a shaped plummet to a position where upward fluid force just balances the weight of the plummet.
ISA DICTIONARY 3RD EDITION
100
RTD
Abbreviation for Resistance Temperature Detector, a temperature transducer that provides temperature information as the change in resistance of a metal wire element, often platinum, as a function of temperature.
ISA DICTIONARY 3RD EDITION
101
SENSING ELEMENT
The element directly responsive to the value of the measured variable.
ISA DICTIONARY 3RD EDITION
102
SENSITIVITY
The ratio of a change in output magnitude to the change in input which causes it after steady state has been reached.
BLH glossary
103
SETPOINT
1.       An input variable which sets the desired value of the controlled variable. The input may be manually set, automatically set or programmed. It is expressed in the same unit as the controlled variable.
ISA DICTIONARY 3RD EDITION
104
SIGNAL
1.       In process instrumentation, a physical variable, one or more parameter of which carry information about another variable (which the signal present)
2.       Information conveyed from a point in a transmission or control system to another. Signal change.
ISA DICTIONARY 3RD EDITION
105
SPECIFIC GRAVITY
1. The ratio of the density of a material to the density of the water at the same condition .                          Specific Gravity: Gf = Liquid at flowing condition referred to water at 60 deg F
2. The density of gas compared to the density of air.
ISA DICTIONARY 3RD EDITION
106
TEMPERATURE COMPENSATION
Any construction or arrangement that makes a measurement device or system substantially unaffected by changes in ambient temperature.
ISA DICTIONARY 3RD EDITION
107
THERMISTOR
 A resistance temperature device utilizing semiconductor material.
IEC902-1987
108
THEMOCOUPLE
Two dissimilar thermoelements so joined as to produce a thermal emf when measuring and reference junctions are at different temperatures.
ANSI/MC96.1-1982
109
THERMOCOUPLE ASSEMBLY
An assembly consisting of a thermocouple element & one or more associated parts such as terminal block, connection head & protecting tube or thermo-well.
ANSI/MC96.1-1982
110
THERMOWELL
1.       A pressure tight receptacle adapted to receive a temperature sensing and provided with external threads or other means for pressure tight attachment to a vessel.
2.       A closed-end tube that surrounds the measuring junction of a thermocouple & RTD
ISA DICTIONARY 3RD EDITION
111
TOLERANCE
Permissible deviation from a specific value; may be expressed in measurement units or percent.
ISA DICTIONARY 3RD EDITION
112
TORQUE
A rotary force such that applied by a rotating shaft at any point on its axis of rotation.
 
113
TUEBINE FLOWMETER
A transmitter which uses a multi-bladed rotor to measure fluid flow rate in a closed conduit. The rotational speed of the rotor, which is proportional to the flow rate, is usually detected by a device mounted outside the conduit.
IEC902-1987
114
UPPER RANGE LIMIT
The highest value of the measured variable that a device that a device can be adjusted to measure.
NOTE: The following components terms are used with suitable modification to the units “measured variable upper range limit ” ,    “measure signal upper range limit”, etc.
ISA DICTIONARY 3RD EDITION
115
UPPER RANGE VALUE
The highest value of the measured variable that a device is adjusted to measure or indicate.
ISA DICTIONARY 3RD EDITION
116
VACUUM
A low-pressure gaseous environment having an absolute pressure lower than ambient atmospheric pressure.
ISA DICTIONARY 3RD EDITION
117
VAPOR DENSITY
The physical property of the vapor phase measured as mass per unit volume; at the coincident pressure & temperature conditions.
 
118
VELOCITY
The rate of change of a position vector with respect to time at any given point in space; the first derivation of distance with respect to time.
ISA DICTIONARY 3RD EDITION
119
VORTEX- TYPE FLOWMETER
A device that uses differential pressure variations associated with formation & shedding of vortices in a stream of fluid flowing past a standard flow obstruction; usually a circular element with a T, shaped cross section—to accurate a sealed detector
ISA DICTIONARY 3RD EDITION
120
WORKING PRESSURE
The maximum allowable operating pressure for an internally pressurized vessel, tank or piping system, usually defined by applying the ACME Boiler & Pressure Vessel Code or the API code
ISA DICTIONARY 3RD EDITION
121
WORKING TEMPERATURE
The temperature of the fluid immediately upstream of a primary device.
ISA DICTIONARY 2ND EDITION

 

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