What is the definition of "beta ratio"?
A filter specification that indicates its capability to trap particles. The beta ratio is determined by comparing the number of particles upstream and downstream of the filter.

Learn more about beta ratio in the class Contamination and Filter Selection 330 below.


Hydraulics and Pneumatics Training


Class Information
Tooling U-SME classes are offered at the beginner, intermediate, and advanced levels. The typical class consists of 12 to 25 lessons and will take approximately one hour to complete.
Class Name:Contamination and Filter Selection 330
Description:This class provides an overview of contamination, hydraulic filters, and fluid maintenance. Includes an Interactive Lab.
Prerequisites: 570120  570140 
Difficulty:Advanced
Number of Lessons:16
Language:English, Spanish
 
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Class Outline
  • Objectives
  • What Is Contamination?
  • The Role of Hydraulic Fluid
  • Contamination Sources
  • Effects of Contamination
  • ISO Contaminant Code
  • Dirt Tolerance and Cleanliness Standards
  • Filter Types
  • Basic Specifications
  • Beta Ratio
  • Pressure Drop
  • Particle Capacity
  • Filter Condition Indicator
  • Fluid Maintenance
  • System Flushing
  • Summary
  
Class Objectives
  • Describe contamination.
  • Describe the role of hydraulic fluid.
  • Describe sources of contamination.
  • Describe the effects of contamination.
  • Identify the meaning of an ISO contaminant code.
  • Define dirt tolerance.
  • Describe the types of filters.
  • Describe basic filter specifications.
  • Identify the meaning of a beta ratio.
  • Describe pressure drop.
  • Define particle capacity.
  • Describe a filter indicator.
  • Describe proper guidelines for fluid maintenance.
  • Identify different system flushing methods.

Class Vocabulary

Vocabulary TermDefinition
absolute rating A filter specification that indicates the size of the largest opening in the filter.
absorbent Used for trapping particulate matter. Absorbent filters consist of surface-type filters like screens and depth-type filters made of cellulose and fiberglass.
beta ratio A filter specification that indicates its capability to trap particles. The beta ratio is determined by comparing the number of particles upstream and downstream of the filter.
built-in contamination The unavoidable presence of foreign particles largely due to the manufacture and assembly of hydraulic equipment. Built-in contamination is also called primary contamination.
bypass valve A type of relief valve that diverts fluid back to the tank once the terminal pressure drop is reached and the filter ceases to allow flow.
catastrophic failure A serious effect of contamination characterized by the sudden and complete loss of component performance. Catastrophic failure can be the result of gradual degradation and intermittent failure.
cavitation An unwanted condition characterized by the formation of cavities on the surface of a metal hydraulic component. Cavitation is commonly caused by entrained air.
cellulose An insoluble fibrous material common in paper and used to make hydraulic filters.
clearance The space between components that allows movement and lubrication.
contaminant Any foreign substance that may cause a loss of efficiency or a breakdown in a fluid system.
contaminant capacity A filter specification that indicates the quantity of particles a filter can hold. Contaminant capacity is also called particle capacity and dirt holding capacity.
contamination The presence of any unwanted substances in a fluid system. Contamination is the primary cause of problems in fluid systems.
corrosion A process by which a metal degrades from a reaction with a chemical such as an acid.
depth-type filter An absorbent filter designed for trapping fine particulate matter. Particles are trapped within this type of filter.
dirt holding capacity A filter specification that indicates the quantity of particles a filter can hold. Dirt holding capacity is also called particle capacity and contaminant capacity.
dirt tolerance An indication of the internal clearance of a hydraulic component. Components with high dirt tolerance have the most clearance, and components with low dirt tolerance have the least amount of clearance.
double oil and filter change A flushing technique involving changing the fluid and filter, circulating the new fluid, and then changing the fluid and filter once more.
downstream In a direction away from the source of power in a fluid system. Downstream in a hydraulic system is in the same direction as the fluid is moving.
environmental contamination The presence of foreign particles that entered a hydraulic system from the surrounding environment. Environmental contamination is also called ingressed contamination.
filter A screen used for limiting contamination by trapping very fine and fine particulate matter.
flow capacity A hydraulic power variable that describes how much fluid is being moved and how much work is being performed. Flow capacity, or flow rate, is usually measured in gallons per minute (gpm) or liters per minute (lpm).
fluid contamination The unavoidable presence of foreign particles in new fluid due to refining, transfer, and storage.
fluid suitability A hydraulic filter specification that indicates whether a filter is compatible with a fluid. Filters that are incompatible with a fluid will quickly fail.
gallons per minute A unit of measurement that indicates the flow capabilities of a hydraulic component. Gallons per minute is abbreviated gpm.
ingressed contamination The presence of foreign particles that entered a hydraulic system from the surrounding environment. Ingressed contamination is also called environmental contamination.
initial pressure drop The lowest pressure drop, usually associated with a brand new filter.
intermittent failure An effect of contamination characterized by unpredictable and unreliable component performance. Intermittent failure can result from gradual degradation and lead to catastrophic failure.
International Organization for Standardization ISO. An organization based in Switzerland that develops and publishes standards for its international membership base.
ISO 4406:1999 A standard method for identifying and describing actual (in fluid) or target (component specification) contaminant levels. ISO 4406:1999 is the official name of the ISO contaminant code.
ISO contaminant code A standard method for identifying and describing actual (in fluid) or target (component specification) contaminant levels. The official name of the ISO contaminant code is ISO 4406:1999.
kidney loop A filter located on an independent circuit intended only for filtration. The kidney loop filter shares a common reservoir with the main circuit.
liters per minute A unit of measurement that indicates the flow capabilities of a hydraulic component. Liters per minute is abbreviated lpm.
lubricity A general term used to describe a lubricant's effectiveness and ability to lubricate. An effective lubricant has a high lubricity.
mechanical flushing A flushing technique that involves forcing a spongy projectile through the system with high-pressure air.
mesh number A basic filter and strainer specification that indicates the number of spaces or openings in one linear inch. Mesh number is also called the sieve number.
multi-pass testing The test used to determine beta ratios of hydraulic fluids. Multi-pass testing involves releasing a controlled amount of particles into a hydraulic system and counting how many get through the filter.
nominal rating A filter specification that indicates the size of the smallest particle the filter can trap.
oxidation A chemical process in which a hydraulic fluid degrades due to a reaction with oxygen.
particle capacity A filter specification that indicates the quantity of particles a filter can hold. Particle capacity is also called contaminant capacity and dirt holding capacity.
particulate matter Solid contaminants including metal, dirt, sand, and dust.
power flushing A flushing technique involving forcing a fluid through a hydraulic system at high speeds.
pressure differential A filter specification that is determined by comparing the pressure directly before and after the filter. Pressure differential is also commonly called the pressure drop.
pressure drop A filter specification that is determined by comparing the pressure directly before and after the filter. Pressure drop is also commonly called the pressure differential.
pressure line filter A filter located at the outlet of the pump.
pressure rating An indication of the amount of pressure a fluid conductor can withstand.
primary contamination The unavoidable presence of foreign particles largely due to the manufacture and assembly of hydraulic equipment. Primary contamination is also called built-in contamination.
return line filter A filter located on the return line just before the line enters the reservoir.
rust A reddish-brown substance caused by metal's reaction with moisture and oxygen.
self-generated contamination The presence of foreign particles in a hydraulic system due to wear and processes like cavitation, oxidation, and rust. Self-generated contamination is also called system wear contamination.
sieve number A basic filter and strainer specification that indicates the number of spaces or openings in one linear inch. Sieve number is also called the mesh number.
silt A collection of particulate contaminants.
silting The buildup of particulate matter inside a hydraulic system.
sludge A form of contamination. Sludge is gummy liquid matter that forms in the reservoir.
strainer A screen used for trapping large and coarse particulate matter.
suction filter A filter located between the reservoir and the pump.
surface-type filter An absorbent filter designed for trapping large particulate matter. Particles are trapped on the surface of this screen-type filter.
system wear contamination The presence of foreign particles in a hydraulic system due to wear and processes like cavitation, oxidation, and rust. System wear contamination is also called self-generated contamination.
terminal pressure drop The highest allowable pressure drop, or the point beyond which the filter ceases to allow proper flow.
upstream In a direction toward the source of power in a fluid system. Upstream in a hydraulic system is in the direction from which the fluid is coming.