Filtration Flashcards
What are the 4 purposes of a filter?
Protect
Clean
Condition
Extend oils life
What do harmful contaminates do?
Reduce efficiency and cause 70% of hydraulic failures
What are the 4 ways contamination effects hydraulic systems?
Increased internal leakage- decreases ability to control flow and pressure. Excess heat
Corrosion of systems
Sticking of parts due to sludge or silting
Seizure of parts
What is silting?
Collection of fine particles in critical areas
What are the 5 major sources of system contaminates?
Contamination built in at the point of manufacture
Hydraulic fluid contamination
Environmental contamination
System wear contamination
Contamination introduced during the servicing process
Dirt particles are measured in what?
Microns - 0.001mm
What is absolute filter fineness?
Indicates the largest particle able to pass through the filter
What is nominal filter fineness?
Particles of nominal pore size are stopped passing through several times, a percentage of particles
What type of application uses grade 1-5
Aeronautics
What type of application uses grade 25-40?
Low pressure systems
What are the 2 types of filter designs?
Surface filter
Deep bed filters
What is surface filter?
Thin layer of woven fabric e.g metal gauze. Disposable and suitable for flushing and commissioning a system
What is deep bed filter?
Compressed, multi fabric fibres which have a much higher dirt retention capacity across the same filter area
What is bypass filtration?
Only part of the delivery is filtered
What is main flow filtration?
Suction, pressure and return lines are filtered
What is the disadvantages of by pass filter?
Low dirt filtering capacity
Only part of the delivery is filtered
What is the advantages of main flow filtration?
Protects pump and prevents cavitation
Where is the pressure line filter located and what are the advantages and disadvantages?
After the pump
Protects valves sensitive to dirt
Only protects valves sensitive to dirt and expensive
Where is the suction line and what are the disadvantages and advantages?
Before the pump
Protects pump
Can starve pump if becomes blocked
Where is the return line located and what are the disadvantages and advantages?
On the return line
Cleans fluid returning to the tank
Contamination can only be removed after passing through components
