403 - Chapter 2 Flashcards
Parallel Flow Path
Pressure only builds in the path of least resistance.
Series Flow Path
Pressure builds at each valve and adds up to a total.
Orifice
Narrowing of pipe or tube.
A pressure drop is created after the orifice.
If pressure is reduced then,
Rate of flow is also reduced.
Doubling diameter:
Halving diameter:
Quadruples area.
Quadruples velocity.
Designing a hydraulic system:
- Stroke length
- Load
- Area
- PSI
The sum of pressure and kinetic energy is constant with a constant flow rate
True
SUS
Saybolt Universal Seconds
Greater the Viscosity Index =
Less change in viscosity due to temperature.
High viscosity:
Thick high resistance to flow.
Increased power consumption due to friction.
Increased pressure drops through valves and lines.
High temp due to increased friction.
Low viscosity:
Increased leaking
Excessive wear
Two types of fluids:
Newtonian
Non-Newtonian
Newtonian fluids
Viscosity is constant and independent to the rate of shear.
Ex: water, most mineral oils, gasoline, kerosine
Non-Newtonian fluids
Viscosity is not constant and not independent of the rate of shear.
Ex: clay, mud, ketchup, tar…most are natural things.
Continuity Equation:
For steady flow in a pipeline the flow rate is e same for all cross sections of a pipe.
Cavitation
The collapse of bubbles that are formed in the pump.
The implosion of bubbles on the surface of the pump, creates pitting and erosion.
Can create intense pressure of up to 10,000 psi of shock.
Cavitation causes:
Breaking shafts
Shortens bearing life
Destroys impellers and volutes
Ruins mechanical seals
