The Numbers behind the Hydraulic Filtration

Articles - Education

Numbers behind filtrationThis article is intended to look a little more in detail the numbers or formulas that are behind the theory of filtration in Glossary Link hydraulics.

 

The experience of the designers and users of hydraulic equipment have found that: over 75% of hydraulic system failures are a direct result of the contamination!

Particle size of substancesTo start, anything that is in the hydraulic Glossary Link fluid like, gases, solid particles and other liquids are contaminants. The most devastating of all of them is solid particles. Gases can cause malfunction and further wear and liquids can generate Glossary Link viscosity alterations that can lead to wear also.

We are going to concentrate in solid contamination.

What is a Glossary Link micron? It is a thousandth of a millimeter or 0.00004" and 1 millimeter is 0.04"

 

Minimum size a human can see: 40 Glossary Link micron

If you compare the size of the substances with the typical clearances in the hydraulic components, you can see that they are very close so damage can happen.

 

Typical clearances in hydraulic components

The cost due to Contamination can be measured on the following aspects:

- Loss of production-MACHINE STOPS

- Replacement of worn items

- More frequent replacement of the oil.

- Higher general maintenance costs.

From different studies, we know that depending on the environment the ingression of foreign particles in a hydraulic system is as follows:

Mobil equipment 108-1010 particles /minute

Factories, contaminated air 106-108 particles /minute

Factories, clean air 105-106 particles /minute

 

Contamination levels ISO code 4406 - 1999During the last 30 years some sets of standards has been developed trying to measure the degree of contamination in a hydraulic system to be able to have it under Glossary Link control.

In 1987 The International Organization for Standardization ISO created the ISO 4406 - 1987 intended to use Method for coding the level of contamination by solid particles in a hydraulic system. This was later updated with ISO 4406 - 1999 that is in use in these days.


ISO Code

Given the importance of particle size, there has been selected 3 different ranges or numbers for the code as follows:

First number for particles > 4 micron

Second number for particles > 6 micron

Third number for particles > 14 micron

So, in the table above the code has:

From 1300 to 2500 particles larger than 4 micron

From 320 to 640 particles larger than 6 micron

From 40 to 80 particles larger than 14 micron. All these per ml of fluid.


Parker particle counterParticle counter resultsTechnology has improved enough in these days to be able to count the particles contained in a sample of hydraulic fluid. The result of an analysis would be a table or just the ISO number like the sample picture at the right side.

 

 

 

 

Maximum contamination levels recomendedHydraulic manufacturers make recommendations of what  the contamination levels are  according to the type of components.

Every hydraulic component has a maximum contamination level suggested.

Let's see a general recommendation.

To establish and maintain a target cleanliness level for a hydraulic system a couple of points should be followed:

 

 

 

 

1. Type of application or type of machine.

2. Maximum Glossary Link flow and Glossary Link pressure.

3. Glossary Link Volume of fluid in the entire system including lines and actuators.

4. Select the most sensitive component( Glossary Link pump, Glossary Link valve or Glossary Link actuator) and find its cleanliness target level.

5. Fluid type.

6. Operating temperature.

7. High vibration or shock?

8. Is the machine critical in the manufacturing process?

9. Can the system cause a safety hazard if it fails?

 

Using the table above, select the most sensitive component and the iso number that corresponds to it; it would be your target. Take into account that if you are using fluids different than petroleum oil, your cleanliness target will be one step cleaner.

 

Filter element

Selection of filters

To begin to understand how we can apply a Glossary Link filter to a hydraulic system, we need to know how they are manufactured.

Surface filters like those made of metal mesh trap particles in its surface and the size of the pass determines the size of the particles trapped. It is possible to filter up to 25 micron.

In-depth filters use a number of layers of random oriented fibres that allow to trap many different particle sizes inside(the whole volume of the Glossary Link filter element). These are the most common filters and can be used in return and pressure lines.

As there is not a specific pore size to filter, manufacturers perform tests on filters to determine its Glossary Link efficiency that is why there is a standard procedure to classify filters according to filtration ability.

A filter's absolute rating is the diameter of the largest hard spherically shaped particle that will pass through a filter under specific test conditions. This does not give any clue about its efficiency but it provides a micron number, ie. 10 micron.

The ISO standard 4572 known also as Multipass filter performance test was created to give a ratio between the number of particles that a filter allows to pass and the total amount supplied to the filter. This number is β (beta) so:

βx = # particles IN / # particles OUT where x is the micron size. 1/βx X 100% is the efficiency.

this number is always >= 1. For example: if a filter has a β10 of 100, that means that the filter has an efficiency of 99.0% of efficiency for particles of 10 micron.


Would you like to try out ipage hosting, they provide reliable green hosting service.

Login

Get access to privileged information. Register today.



Hydraulics Knowledge POLL

Is the pressure a result of the flow?
 
Hydraulic Calculations 2.0
Hidraulic Calculations 2.0

BLOGS Latest Posts

hidrocel  →  NEW GENERATION BENT AXIS PISTON PUMPS AND MOTORS

04.05.2013 19:25 0 0

Çelebi Hidrocel ® Axial Piston Pumps, Axial Piston...

Memo63  →  Motor Hidraulico vs Motor Electrico

03.14.2013 02:14 1 0

Hola todos Espero alguien pueda ayudarme. Deseamo...

Hydraperm  →  Hydra-Perm-Co Ltd - PERMCO UK, European & Middle Eastern Distributors

08.29.2012 18:15 2 0

// Hydra-Perm-Co Ltd is an international...

nefacio  →  Consulta sobre cañería de salida de bomba

08.24.2012 00:23 1 0

Hola, tengo una consulta sobre la elección del dia...

kobra  →  Bienvenidos a KOBRA Paintball fields

07.22.2012 03:30 0 0

// Puede visitar nuestro sitio en Face...

juanqui  →  SERMATER; SERVICIO DE REPARACION Y MANTENCION DE MAQUINARIA PESADA EN TERRENO

06.16.2012 08:10 0 0

// SATISFACEMOS LAS NECESIDADES DE REPAR...

jneschii  →  Buscando un motor hidráulico que funcione eficientemente desde baja velocidad.

06.06.2012 16:37 3 0

//   Hola, buenos días. Muchas gracias...

BLOGS LatestComments

Motor Hidraulico vs Motor Electrico

Buenos dias, Para empezar, es mejor saber cual es ...

Twitter

Latest Hydraulics News

HYDRAULICS - News

Recent Content Added

Copyright © 2008 - 2014 Hidraulica Practica. All Rights Reserved.

Joomla Templates designed by Joomla Hosting