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Media Grade Selection Guide:
The selection of a suitable filter element media depends on first determining the target cleanliness for the system. The next step is to adjust the level based on consideration of specific system operating conditions. These stress factors result in an adjusted target cleanliness level that can be used to select the proper media code.
| Media Grade Selection Process |
Step 1: Determine target cleanliness |
Step 2: Adjust target for stress factors |
Step 3: Select a media grade to achieve target |
Step 1: Determine Target Cleanliness
The code levels below show typical recommended target cleanliness levels that are based on data from several hydraulic manufacturers. For recommendations for your specific system requirements contact Western Filter or your distributor.
| Component |
1-3000 psi |
3000 > psi |
Hydrostatic Transmission |
18/16/14 |
16/14/11 |
Fixed Displacement Piston Pump |
18/16/13 |
17/15/12 |
Variable Displacement Piston Pump |
18/16/13 |
17/15/12 |
Variable Displacement Vane Pump |
18/16/13 |
17/15/12 |
Gear Pump |
20/18/15 |
19/17/14 |
Vane Motors |
19/17/14 |
18/16/13 |
Fixed Displacement Piston Motor |
17/15/13 |
16/14/11 |
Variable Displacement Piston Motor |
18/16/13 |
17/15/12 |
Solenoid Directional Control Valve |
18/16/13 |
17/15/12 |
Servo Valve |
16/14/11 |
15/13/10 |
Cartridge Valve |
18/16/13 |
17/15/12 |
Proportional Directional Valve |
17/15/12 |
16/14/11 |
Industrial Gearbox Bearings |
17/15/13 |
16/14/11 |
Determine the target cleanliness requirement by selecting the most contaminant sensitive component in the system (lower codes are cleaner).
Step 2:
Adjust Target for Stress Factors
Based on Application |
Minimum Temperature < 0ºF |
Maximum Temperature > 160ºF |
High Vibration or Shock |
Process Critical Component |
Safety Hazard |
Fluid not 100% Petroleum Oil |
If any two answers are “Yes”, decrease the ISO cleanliness levels by one code: (i.e. 19/17/14 becomes 18/16/13)
Step 3:
Select a Media Grade
Adjusted Target Cleanliness |
Suggested Media Grade |
20/18/16> |
C20 |
Between 18/16/15 & 20/18/15 |
C10 |
Between 16/14/13 and 18/16/14 |
C05 |
16/14/12 < |
C03 |
Cleanliness levels assume full flow through pressure line and return line filters. For systems with long periods of pump compensation, a “kidney loop” system connected to the main reservoir is recommended. For systems with expensive or dirt sensitive components, add a filter of the same media grade as the main filter of that component upstream.
Seal Code and Fluid Compatibility
Most Western Filter elements and housings are available with the following seal materials:
Code B – Standard Seal Material: Buna (a.k.a. Nitrile or NBR)
Compatible with petroleum, diesters, water, and water glycol fluids. Recommended for most general-purpose applications. Operating temperature range –65 to +250ºF.
Code V – Optional Seal Material: Viton (a.k.a. Fluorocarbon or FPM)
Recommended for higher operating temperatures, Petroleum, Silicate Ester, Diester, and most Phosphate Esters. Not compatible with Skydrol or Skydrol 500. Operating temperature range –20 to +350ºF. (+650ºF for limited periods)
Code E – Optional Seal Material: EPR (a.k.a. Ethylene Propylene Rubber, EPM, or EP)
Recommended for use with phosphate Ester, Steam, (to 400ºF), Water, and Ketones. Highly recommended seal material for Skydrol and Skydrol 500. Not recommended for petroleum or Diester based fluids. Operating temperature range: -65 to +300ºF.
Commonly Used Hydraulic Fluids:
Petroleum:
A thick, flammable, yellow to black mixture of gaseous, liquid, and solid hydrocarbons that occurs naturally beneath the earth’s surface. It can be separated into fractions including natural gas, gasoline, naphtha, kerosene, fuel, hydraulic and lubricating oils, paraffin wax, and asphalt and is used as raw material for a wide variety of derivative products. All Western Filter media Packs™ with standard code B Buna seals are compatible with petroleum-based fluids.
Diester Oil:
A synthetic lubricating fluid made from esters: also called ester oil or an organic ester, formed by reacting a dicarboxylic acid and an alcohol; properties include a high viscosity index (V.I.) and low volatility. With the addition of specific additives, it may be used as a lubricant in compressors, hydraulic systems, and internal combustion engines. Use BetaPore™ elements with code E EPR seals.
Ethylene Glycol:
A chemical compound widely used an automotive antifreeze (coolant). In its pure form, it is odorless, colorless, syrupy liquid, with a sweet taste. Ethylene glycol is toxic, and its accidental ingestion should be considered a medical emergency. BetaPore™ element Paks™ with standard code B Buna N seals are the preferred choice for Ethylene Glycol fluids.
Phosphate Ester:
Phosphate Ester™ fluids are also referred to as synthetic fluids and are compatible with all Western Filter Media Paks™. Size filters using viscosity corrections as indicated within our catalog. Code E EPR seals should be used with Phosphate Esters including Skydrol™ and Skydrol 500™.
Skydrol / Skydrol 500:
A fire resistant used on all commercial aircraft manufactured in the U.S. Phosphate Ester-based aviation hydraulic fluids are purple fresh out of the can and may change color during service. Color is not a reliable indicator of fluid quality, and there is no in-service specification for fluid color. The fluid should be clear with no cloudiness or suspended solids. BetaPore™ elements only should be used for Skydrol and Skydrol 500™ applications using the code E (EPR) seal option.
High Water Based Fluids (HWF or HWBF):
A fire resistant mixture of clean water and a soluble mineral based fluid, or a synthetic fluid and other chemicals to prevent the formation of algae. Ratios as high 95/5 (96% water / 5%glycol) are common but may be as high as 98:2 or as low as 90:10. Often used in underground mining operation or high ambient temperature industrial applications, BetaPore™ element Paks™ with Code B or V Buna N or Viton seals are compatible with both types of fluid and should be sized the same as with 150 SSU petroleum based fluids. Cavitation can a problem with these fluids and care must be taken to insure proper suction characteristics.
Filter Placement
Filter Location:
With no defined rules regarding location of filters in a fluid system, every effort should be made to achieve the optimum positioning so that the fluid system will function with the highest degree of efficiency. Several types of filters perform various functions required in the fluid system, and can be described by their location.
Pressure Filters are the primary filters in fluid systems and are located down stream from the main pump. They are exposed to full system pressure and must not allow fluid to bypass the filtration medium. Fluid bypass can be prevented by used of a non-bypass filter or device that restricts flow as differential pressure across a dirty filter increases. The main function of a pressure filter is to protect all components from contamination generated by the pump. However, it does not protect components from contamination generated by each other.
Return Filters are located down-stream of working system components and upstream of fluid reservoir. The function of a return filter is to remove contaminants generated by system components before the fluid returns to the reservoir.
Kidney Loop Filters are located in a separately powered, independently operated loop of the main fluid system. The purpose of the kidney loop filter is to cleanse reservoir fluid.
Point-of-use filters are pressure filters located immediately upstream of critical components for the purpose of collecting contaminants generated by other components
Contamination Control
Contamination:
The primary function of a filter is to reduce or eliminate undesirable contaminants from fluids prior to their flow through sensitive system components. These contaminants, when allowed to flow freely in a system can cause wear, malfunction, and failure of many expensive components.
Regardless of conditions, contamination is inherent in every fluid system. It is influenced by many factors, generated by mechanical components, and collected by the fluid as it circulates.
There are several factors to consider when determining fluid systems needs and selecting filters. These include, but are not limited to: the complexity of the fluid system, the various functions of the system, the type(s) of components used, and the fluid itself. A complex system would require several filters to protect each component adequately.
Contaminant Sources:
External Contamination, also known as ingressed contamination may stem from many environmental sources. However, there are four major ways contaminants can enter a system: reservoir vent ports (breathers), power unit or system access plates, components left open during maintenance, and faulty seals or o-rings. Generally ranging in size from 1-500 microns, these contaminants may be dust, dirt, corrosion, adhesives, paint, etc.
Internal Contamination is the most dangerous contamination to a system. Internal contamination is the contamination generated by the system itself. Particles created by such conditions as adhesive wear or galling, abrasive wear, surface fatigue, and erosion are “work hardened” to a greater material hardness than the surface from which they came and are very aggressive in causing further wear to the system. Pumps generate contaminants during normal operation that if not immediately removed, result in elevated contamination levels wear effect, causing more particulate contaminant, causing more wear, and so on until the inevitable failure occurs. Other internal sources of concern include chemical wear, excessive heat, and microbiological growth.
One noteworthy and unique source of internal contamination is filter failure. A common cause of catastrophic failure is improper maintenance and poor quality filtration products. When a filter element fails, it collapses and unloads much or all of the contaminant (both internal and external) previously captured. This extreme concentration of system contamination is suddenly released downstream and whatever is in its path may be severely damaged or destroyed.
Contaminated New Oil, an often-overlooked source, is a major contributor to system contamination. Although hydraulic and lubrication oils are refined and blended under relatively clean conditions, the fluid travels through many hoses and pipes before it is stored in drums or in a bulk tank at the users facility. At this point the fluid is no longer clean. The pumps, the lines, and the drums it has traveled through have contributed metal, rubber, flakes of scale, corrosion, and exposure to dirt and dust.
Storage tanks are severe problems as water condenses on the inner walls, causing rust particles that then enter the fluid. Contamination from the atmosphere also finds its way in to the tank when sufficient air breather filtration is not installed.
Built in Contamination from new machinery is most always a cause for concern. Typical incidences are burrs, chips, flash, slag, weld splatter, dirt, dust, fiber, sand, moisture, pipe sealant, paint, flushing solution, and almost anything imaginable.
