Flashcards in Fluid Conditioning Deck (33)
What are four sources of ingressed contamination?
breathers, pistons, shafts, new lubricant, bad seals, failed filters, open or poorly sealed inspection hatches.
What is ISO 4406?
ISO Cleanliness standard that measures particles in oil
What does ISO 16/14 mean?
an indication of the number of particles greater than 5 microns/15 microns.
Note: There are proposals to add a 2 micron standard, as well as to change the standard to 4 microns/6 microns/14 microns.
What is a beta ratio?
Beta ratio is the ratio of particles greater than a given size going into a filter to the number coming out.
What does β 3 200 mean?
It is the rating given a filter whose absolute rating is 3 microns and that for every 200 particles greater than 3 microns in size entering the filter, only one will exit.
What is a graded pore filter?
A graded pore filter is one whose pores become smaller near the fluid exit.
What is more effective, a fixed pore or a non-fixed pore filter?
A fixed pore filter is more effective because fibers are bonded. Non-fixed pore filters are more subject to breakage.
The three forms of water in lube oil are _______, _______, and _______.
Name at least three negative effects the presence of water will have on the properties of a lubricant.
1. It causes rust and corrosion
2. Hydrogen embrittlement and water etching/erosion
3. It promotes oxidation
4. Depletes additives and reduces
How does emulsification of water affect a lubricant’s viscosity?
It increases until the proportion of water is very high, then it decreases.
What is the smallest dot that most people (under age 40) can see with the naked eye?
40 microns (particles of 5 microns can cause damage in lubricating oil systems)
Other than continuous filtering, what are other options that can be used to clean up systems that tend to get contaminated?
First, control the source of contamination.
Then try settling out water and contaminants, raising the system temperature to drive off water and facilitate settling, adding portable filters, centrifuging or vacuum dehydrating.
Name three types of filter ratings?
Nominal Rating: An arbitrary micrometer value indicated by the filter manufacturer. Due to the lack of reproducibility rating is depreciated.
Absolute Rating: The diameter of the largest hard spherical particle that will pass through filter under test condition.
Filtration Ratio: The ratio of particles greater than a given size upstream divided by the number of particles of the same size downstream.
Give recommended beta ratios for ball bearings, roller bearings and industrial gear boxes.
Ball Bearings ß (1 to 6) = 200
Roller Element Bearings ß (1 to 3) = 200
Gears ß (3 to 12) = 200
What are two primary objectives to consider when selecting a filter?
What are the two most important numbers that indicate the capacity of a filter?
Apparent dirt capacity
Retained dirt capacity
What are the three major categories of component failure?
Clearance sized particles have what three effects on valves?
slow response/instability their effectiveness
It increases oil viscosity and plugs filters. It decreases bearing life and oxidizes babbitt. It freezes and promotes bacterial growth. Minerals may produce hard deposits. It may cause foam, although some studies dispute this.
What is the typical clearance in a servo valve?
1 to 4 microns
Piping selection is based on ________, which is measured in FPS.
Piping must be large enough to prevent _________ in the pump suction lines.
What are the three steps of Systemic Contamination Control?
Set a target cleanliness level
Select filters & filter placement to achieve target
Sample fluid & confirm achievement
Name four sources of contamination?
Contaminated new oil
Built in contamination
Ingressed (Introduced from outside)
Internally generated contamination
Name four sources of contamination from outside sources?
Reservoir vent ports
Power unit access plates
Cylinder rod seals
Name three types of Generated Contamination?
Explain the “chain reaction” caused by abrasive wear?
Abrasive particles become work hardened (harder than parent surface)
Work hardened particles produce greater wear and move particles
New particles become work hardened
Chain reaction accelerates wear unless particles are removed by filtration.
Name three types of adsorbent filters.
A servo system should have a filtration range of __________.
Name four types of filter material.