Pressure

Question 1

What is pressure?

Answer 1

Pressure is the amount of force acting on a specific amount of surface area

Question 2

How is pressure typically measured?

Answer 2

Pressure is typically measured in pounds per square inch (psi)

Question 3

If a 100-lb weight is placed on a block with a surface area of 10 in², what is the pressure?

Answer 3

10 psi

Question 4

What is standard atmospheric pressure in psi?

Answer 4

14.7 psi

Question 5

What are other units of pressure measurement besides psi?

Answer 5

Inches of mercury, millimeters of mercury, millibars

Question 6

What is the relationship between psi and inches of mercury?

Answer 6

1 psi = 2.04 ‘Hg

Question 7

What is the relationship between psi and millimeters of mercury?

Answer 7

1 psi = 51.7 mm Hg

Question 8

What is the relationship between psi and millibars?

Answer 8

1 psi = 68.9 millibars

Question 9

Describe how pressure is measured in inches of mercury.

Answer 9

Involves filling a test tube with mercury, turning it upside down, and measuring the height where gravity and atmospheric pressure equal out

Question 10

What does gauge pressure (psig) refer to?

Answer 10

Pressure reading that is over and above ambient pressure

Question 11

What does a gauge pressure gauge read when no pressure is being created?

Answer 11

Zero

Question 12

What is absolute pressure (psia)?

Answer 12

Pressure that includes atmospheric pressure in its reading

Question 13

How is absolute pressure calculated?

Answer 13

Absolute pressure = gauge pressure + atmospheric pressure

Question 14

When would a psia gauge be useful?

Answer 14

In applications like manifold pressure on a piston engine

Question 15

What is differential pressure (psid)?

Answer 15

The difference between pressures being read at two different locations within a system

Question 16

Give an example of where differential pressure might be measured.

Answer 16

In a turbine engine oil system as it enters and leaves the oil filter

Question 17

What happens to the pressure drop across a filter as it clogs?

Answer 17

The pressure drop becomes greater, potentially causing an advisory light to come on

Question 18

What does a differential pressure gauge measure in an airplane?

Answer 18

The difference in pressure between the inside and the outside of the airplane

Question 19

What could happen if the pressure difference in an airplane becomes too great?

Answer 19

The structure of the airplane could become overstressed