Hydrostatics and Pressure Measurement

Question 1

What is Hydraulics?

Answer 1

• The laws of pressure and flow of fluids and their applications to engineering.

Question 2

What is hydrostatics?

Answer 2

The study of fluids at rest.

Question 3

What is Pascal’s law?

Answer 3

The pressure of a confined fluid acts equal in all directions with undiminished intensity, perpendicular to the containing walls.

Question 4

Whats a common example of Pascal’s Law?

Answer 4

Pressure in a Hydraulic Jack.

Question 5

What pressure type (Gauge or Atmospheric) is usually used in Hydraulics?

Answer 5

Gauge Pressure

Question 6

Where does pressure act on the walls of a full water tank with unit width?

Answer 6

1/3 of the height from the base.

Question 7

What are the three types of pressure measuring device? Briefly describe how they work.

Answer 7

• Manometer
  
  • Measures the pressure in fluid as a column of liquid.
• Mechanical Instrumentation
  
  • Pressure acts on a diaphragm or piston.
• Electronic Instrumentation
  
  • Transducers or Transmitters

Question 8

Name three types of Manometer.

Answer 8

• Barometer - Measures atmospheric.
• Piezotube
• U-Tube Manometer

Question 9

What are the two types of U-tube manometer?

Answer 9

1. U Tube Manometer - Open to atmosphere on one side.
2. U Tube differential manometer - both sides of the U are connected at points in the pipeline.

Question 10

What’s imprortant to remember when calulating pressure using manometers?

Answer 10

• Always draw an X–X line through the point where two fluids are at the same level.
• From that point, calulate relevant column presuures using (ro)gh.

Question 11

What are three types of mechanical pressure gauge?

Answer 11

• Borden gauge
• Bellows gauge
• Diaphragm gauge

Question 12

What are the two types of electronic pressure senor and how do they vary?

Answer 12

• Transducer:
  
  • Converts energy from one form to another.
  • Generally weak signal, only useable over short distances.
  • Output is dependant on input.
• Transmitter:
  
  • When a transducer is amplified, using and amplifier, it becomes a transmitter.
  • Amplifier takes the transducer signal, converts it to an output and then transmits it.
  • Signal independant of Input

Question 13

What’s the typical signal for an electronic pressure sensor?

Answer 13

• 4-20mA
  
  • Allows a zero mA error reading.

Question 14

What is the equation for pressure in a column of fluid?

Answer 14