CLASSIFICATION OF INSTRUMENTS, CONTROLS, VARIABLES Flashcards
-An instrument which, if not conforming to specification, could potentially compromise product or process quality and
safet
CRITICAL INSTRUMENT
An instrument whose function is not critical to product or process quality, but whose function is more of an operational
significance. An instrument whose function is not critical to product or process quality, but whose function is more of an
operational significance.
NON-CRITICAL INSTRUMENT
-An instrument whose function is not critical to product quality, not significant to equipment operation, and not used for
making quality decisions.
REFERENCE ONLY
-in process industries it refers to the regulation, command or direction of all aspects of the process
CONTROL
2 TYPES OF CONTROL
MANUAL CONTROL
AUTOMATIC CONTROL
-refers to the methods of changing or refining raw materials to create end products
PROCESS
-the regulation or manipulation of variables influencing the conduct of a process in such a way as to obtain a product of
desired quality and quantity in an efficient manner
PROCESS CONTROL
-an arrangement, set or collection of physical components connected or related in such a manner as to form and/or act as
an entire uniT
SYSTEM
-an arrangement of physical components connected or related in such a manner as to command, direct or regulate itself
or another system.
CONTROL SYSTEM
-an arrangement of two or more instruments connected together to
perform a unified task
INSTRUMENTATION SYSTEM
-a process management system designed to maintain a process variable at a desired set point.
CONTROL LOOP
2 TYPES OF CONTROL LOOP
CLOSED AND OPEN CONTROL LOOP
–exists when a process variable is measured, compared to a setpoint and action is taken to correct any deviation from
setpoint.
CLOSED LOOP
-exist when the process variable is not compared, and action is taken not in response to on the condition of the process
variable
OPEN LOOP
-a value for a process variable that is desired to be maintained
SETPOINT
ELEMENTS OF THE INSTRUMENT LOOP
- Process
- Measuring Element
- Receiving Element
- Final Control Elemen
-Any operations or sequence of operations involving a change of energy, state, composition, dimension or other properties
that may be defined with respect to a datum/data.
Process
- any variable property of a process
PROCESS VARIABLE
- any input variable that seats the desired value of the measured variable.
SET POINT
– outputs signal generated in response to a change of a process variable.
CONTROLLER OUTPUT
-a process variable linked to the controller output that is used to influence the measured variable.
Manipulated variable
MAJOR PROCESS VARIABLES
- PRESSURE
- LEVEL
- FLOW
- TEMPERATURE
MINOR PROCESS VARIABLES
ANALYSIS
POSITION
SPEED
+MORE
A combination of two or more instruments or control functions arranged so that signal pass from one to another for the
purpose of measurement and/or control of a process variables
Instrumentation & Control Loop or Instrument Loop
-The regulation or manipulation of variables influencing the conduct of a process in such a way as to obtain a product of
desired quality and quantity in an efficient manner
PROCESS CONTROL
The determination of the magnitude of a variable (VALUE
MEASUREMENT
The determination of the existence or the presence of a variable
DETECTION
The limit or extent of variation.
RANGE
The lower limit is called _______
LRV
the upper limit is called _______
URV
The number of units between two limits
SPAN
a signal that has no discrete positions or states and changes value.
ANALOG SIGNAL
a signal that generates or uses binary digit signals to represent continuous values or discrete
states.
DIGITAL SIGNAL
TYPES OF MEASURING OUTPUTS
- Sensor
- Transmitter
- Transducer
- Process Switch
The part of Instrument loop or instrument that first senses the value of a process variable, and that assumes a
corresponding, predetermined, and intelligible state or output.
- Integral part of loop that first senses the value of a process variable that assumes a corresponding predetermined
state and generates an output signal indictive of or proportional to the process variable.
SENSOR
A device that senses a process variable through the medium of a sensor and has an output whose steady-state
value varies only as a predetermined function of the process variable.
TRANSMITTER
A general form of a device that receives information in the form of one or more physical quantities, modifies the
information and/or its form, if required, and produces a resultant output signal.
TRANSCUDER
-a device that converts one type of signal into another type of signal.
CONVERTER
-a device that converts a reading from one sensor or transducer into a standard and transmits that signal to a monitor or
controller
TRANSMITTER
