Instrumentation 2 Test Flashcards
What makes temperature measurements unique when compared to other process variables?
It is not measured directly
It is inferred by monitoring temperatures affects on other things
What is exothermic?
The emission of heat
What is endothermic
Absorption of heat
What is he transfer?
Process of thermal energy flowing from a body of high energy to a body of low energy
Four types of temperature measurements
Fahrenheit
Celsius
Kelvin
Ranking
There’s a thermowell?
Protects temperature sensors from harsh environments
Four main types of temperature sensors?
RTD
Thermocouples
Thermistor
Integrated circuit
Fahrenheit to Celsius
(F-32) / 1.8 = C
Celsius to Fahrenheit
C x 1.8+32=F
Celsius to Kelvin
C+273.15=kelvin
Rankine to Fahrenheit
R-459.67= F
What are two thermal couple types
Copper Constantin
Iron constantin
What is a thermopile
Set of thermocouples arranged for measuring small quantities of radiant heat usually wired in series
What is a dry well calibrator
Used for accurate liquid free calibrations of temperature devices
(RTD’S
Thermistors
Thermocouples)
Most common type of RTD
100-ohm, platinum
What device is the basis of most pneumatic instruments
Nozzle flapper system
Most common type of gas utilized for pneumatic signaling
Dry instrument air
Most Common pneumatic Signal
3-15 psi
How to find accuracy
(Deviation/span)x 100
How should process tubing be installed
As short as possible
Relationship between Flow through a valve and the area of the opening
Proportional to the square root of the differential pressure across the valve times the area of the opening
Difference between when your valve and nonlinear valve
When your valve when open 50% there is 50% of the max flow rate 25% open means 25% of the max flow rate the relationship is not true for a nonlinear valve
What is a I/P transducer
Convert a current to pressure
Fail open
Applied air acts against the spring in the actuator to cause the valve to close upon loss of air the spring will force the valve to open also referred to as direct action
Fail closed
Opposite of feel open also known as reverse action
Two most common analog signals used in the industry
1-5 VDC
4-20 mA
both utilize live zero
Single loop controller
Program stored into permanent memory cannot be changed or adapted to fit a working process other than what it was designed for
Protocol
Describes how data is to be exchanged
Alpha numeric
Character set the controls both letters and digits
Controlled system
Part of the system under control also known as the process
How do you controllers execute the program logic
Sequentially
What should be done before configuring a smart transmitter
What is the control loop in manual mode
What’s the what’s the security switch be in
Off state
Which process variable measurement may require the technician to configure transmitter for a square root output rather than a linear outlet
Flow-due to the relationship between flow velocity and the square root of the differential pressure measured across the restriction
Digital to analog trim is performed on the smart device
Set the output of the device so thatwhen it tries to help with the necessary current it really is the current
Damping procedure is completed
Adjusts how often the instrument updates the output in response to the sensor
Sensor zero trim is performed
One point calibration that the Stabley S-t is the starting point for the sensing element
Relationship between installation and accuracy
Transmitter is mounted in a position that changes the actual process pressure that is measuring the overall goal of maintaining efficient and accurate an automatic process cannot be achieved
Recommended spacing for in front of an instrument in order to maintenance and calibrate
6 inches
Vent valves should be oriented with a liquid and what direction
Taps should be located on bottom of process line
Vent valves for a gas should be located where
Tabs are at the top of device
Discrete signal
Input signal receive from controller movie either on or off
Gas measurement
Process to Tubing should be able to routed down word from the transmitter to the process
Process to Bing for a liquid
Upward
Process tubing for gas
Downward
Impulse to being is connected to steam
Tubing will be filled with water to isolate the instrument from the heat of the steam
Gas tubing cannot be routed without valleys we’re moisture may accumulate
Drains must be mounted to allow moisture to be removed
Routing electrical conduit to a transmitter
Care must be taken so that the signal is not induced by stress voltage or electrical noise
