Module 3- Pressure Measurement Standards and Pressure

Question 1

How is flow inferred from pressure

Answer 1

measure of the press dropped across a restriction

Question 2

Define pressure

Answer 2

the measurement of force acting on the area of a surface

Question 3

Pressure formula

Answer 3

Force/Area

Question 4

Pressure units

Answer 4

pounds per square inch PSI
Pascals Pa

Question 5

1 PSI in Pa

Answer 5

7000

Question 6

What does pressure vary depending on

Answer 6

weather pressure fonts, sea level

Question 7

Define Gauge pressure

Answer 7

the pressure measured relative to the atmospheric pressure. It is the difference between the absolute pressure of a system and the atmospheric pressure surrounding it

Question 8

Gauge pressure Formula

Answer 8

Absolute pressure - Atmospheric pressure

Question 9

A gauge pressure device will indicate zero when

Answer 9

bled down to atmospheric pressure

Question 10

Define absolute pressure

Answer 10

the total pressure exerted on a system, measured relative to a perfect vacuum (where there is no pressure)

Question 11

Absolute pressure formula

Answer 11

Gauge pressure + Atmospheric Pressure

Question 12

When would an absolute pressure indicator indicate atmospheric pressure

Answer 12

when completely vented down to atmosphere and it would not indicate scale 0

Question 13

When Absolute pressure is zero what does is Gauge pressure

Answer 13

-101.3 kPa(g)

Question 14

When gauge pressure is 0 what is absolute pressure

Answer 14

101.3

Question 15

What are the 3 basic functions of pressure detector

Answer 15

ICA
Indicate
Alarm
Control

Question 16

List pressure sensor

Answer 16

BBC MS
Bourdon tube
Bellow
Pressure Capsule
Manometer
Strain gauge

Question 17

Describe the manometer

Answer 17

a fluid-filled
tube where an applied gas pressure causes
the fluid height to shift proportionately

Question 18

why is a manometer consider a differential pressure instrument

Answer 18

because it indicates the
difference between two pressures by a shift
in liquid column height

Question 19

List the types of manometer

Answer 19

U tube manometer
Well manometer
Raised well manometer
inclined manometer

Question 20

What equation is the manometer based on

Answer 20

P1- P2 = rho g h

Question 21

Errors associated with manometer

Answer 21

manometer zero
meniscus
parallax
Vapourization of fluid

Question 22

Three pressure standards used with manometer

Answer 22

a standard atmosphere
A vertical column of water
A vertical column of mercury

Question 23

properties of manometer liquid

Answer 23

low temperature coefficient of expansion
low surface tension
low vapor pressure
immiscible with other liquids

Question 24

What are the typical gauge elements

Answer 24

Bellows
Bourdon Tube
Metallic Diaphragms
Capsules

Question 25

Bellows are extremely... and provide

Answer 25

extrmely sensitive and provide power for recording activating and indicating mechnisms

Question 26

Define hookes law

Answer 26

s, the force required to stretch an elastic object such as a metal spring is directly proportional to the extension of the spring

Question 27

Hookes law formula

Answer 27

F=-kx

Question 28

Define the bellows

Answer 28

collapsable tank consist of corrugated or pleated tubes that can expand and contract along their length pressure is applied to the internal volume and as the pressure changes it expands or contracts to generate an an electrical signal that causes the gauge pointer to move

Question 29

Pressure increase in bellows

Answer 29

If the pressure inside the bellows exceeds the external pressure, the bellows will expand.

Question 30

Pressure decrease in bellows

Answer 30

If the external pressure is greater than the pressure inside the bellows, it will cause the bellows to contract.

Question 31

Describe the make up of a bourbon tube

Answer 31

Thin arch shaped tube that is flattened so that is cross sectional area is that of an ellipse that is permanently fastened at on end

Question 32

Principle of operation of a bourdon tube

Answer 32

When pressure is applied to the system is the tube cross section returns to a circular shape and this causes the tube to straighten, the tip of the tube traces a curve this tip movement generates an electrical signal to move theguage pointer

Question 33

Types of bourdon

Answer 33

spiral and helical

Question 34

Diaphragms