T3 Flashcards
What is sludge?
A thick gel-like two-phase substance composed of liquid and solid particles
Two situations where fluid temperature increases
-Increases during operation due to pressurization of the oil
-Increases when the fluid expands as it leaves the pressure relief valve
State the main difference between absorbent and adsorbent depth-type filters.
-Absorbent filters mechanically trap contaminants in oil
-Adsorbent filters mechanically trap contaminants and chemically remove them
Why are absorbent filters not used in hydraulic systems?
They may remove important additives from oil
What are filter condition indicators?
They sense the pressure difference between the filter inlet and outlet.
Where are filters placed in a hydraulic circuit?
-Pump inlet
-Working lines between pump and actuator
-On the return line before entering the reservoir
What is the main difference between sump strainers and suction filters in terms of their location?
-Sump strainers are installed at the pump inlet
-Suction filters are installed above the fluid level in the tank.
Why should suction filters be carefully inspected and replaced once clogged?
The clogged filter causes more reduction to the vacuum pressure at the pump inlet.
List 3 types of heat exchangers used in a hydraulic system.
-Radiators and finned conductors
-Shell and tube
-Immersion heat exchangers
How is the housing of working line filters different from return line filters?
The housing of working line filters are designed to stand the high working fluid pressure.
What is the purpose of fins on some types of heat exchangers?
The fins increase the exposed surface area for more heat transfer.
Which is more efficient in transferring heat: Liquid to liquid or air to liquid heat exchangers?
Liquid to liquid
Why are immersed electric heaters equipped with thermostats?
To limit the amount of heat delivered to the fluid. This helps avoid overheating.
What are two ways by which contaminants enter the system during operation?
- Dust may enter the system during rod retraction
- Dust and moisture could enter through the tank breather
What should be done to the system to ensure an adiabatic process?
The system should be perfectly insulated so no heat transfer is allowed.