Gates Belts & Applications - Tips and guidelines written by Gates Industrial Engineers

Hose Cleanliness – Methods of measurement Part 3

Tuesday, April 25, 2017

posted by Brent at 9:21 AM 0 comments


There are three principal methods to measure the contamination level in a component, circuit, or system. The methods are Gravimetric Measurement (ISO 4405); Particle Size Distribution Analysis (ISO 4406 or NAS 1638); Maximum Particle Size Analysis (ISO 4407).

Maximum Particle Size Analysis (ISO 4407)  

This evaluation is done using a microscope. A microscope is used to identify and measure the size of individual pieces of contaminant. Particle size is important in reference to maximum clearances of hydraulic components.

Whether hydraulic assembly cleanliness applies to you or not, it is worthwhile to understand the significant impact that contamination levels can have on the life of hydraulic system components.

Implementing a thorough cleanliness system may have a significant impact on warranty returns for hydraulically powered equipment.

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Hose Cleanliness – Methods of measurement Part 1 - Gravimetric Measurement

Tuesday, March 28, 2017

posted by Brent at 1:58 PM 0 comments


There are three principal methods to measure the contamination level in a component, circuit, or system.

The methods are: Gravimetric Measurement (ISO 4405); Particle Size Distribution Analysis (ISO 4406 or NAS 1638); Maximum Particle Size Analysis (ISO 4407).
 
This discussion will cover Gravimetric Measurement.

Gravimetric Measurement (ISO 4405) is a reporting method that references the total mass of
contaminant found in a hydraulic component. This total mass of contaminant measurement is then normalized by the total internal component surface area of a hydraulic component. A fluid is used to
dislodge contamination in a hose assembly and is then poured through a membrane catch filter.

An analytical balance is used to measure the total mass of contaminate which has been flushed out of a component. The total mass of contaminate and is referenced to the surface area or volume of the assembly.

Gates currently offers a system of four Gravimetric measurement (ISO 4405) levels of cleanliness for hydraulic assembly that can be used to meet or exceed cleanliness requirements.

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Fluid Power - Learn the Terminology

Monday, December 5, 2016

posted by Brent at 7:47 AM 0 comments

Burst Pressure - The pressure that causes rupture.  Reference pressure intended for destructive testing purposes and design safety factors only.

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Fluid Power - Learn the Terminology

Buffing: The partial removal of the hose cover in order to put on a coupling. A stone wheel is typically used to grind or buff the cover to remove the cover material.

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Learn the Terminology

Monday, November 7, 2016

posted by Brent at 11:06 AM 0 comments


Cut-Off Length:  The length of that part of the coupling not directly in contact with or applied to the hose. Subtract the sum of the cut-off length of the two couplings from the total length of the assembly, and you will have the approximate hose-cut length to be replaced.
Dash Size:   A shorthand method of denoting the size of a particular end fitting or the inside diameter of a hose.  Measured in 1/16 of an inch (i.e., -4 = 4/16” or ¼”).

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Hose Cleanliness – Methods of measurement Part 2

There are three principal methods to measure the contamination level in a component, circuit, or system:

1) Gravimetric Measurement (ISO 4405)

2) Particle Size Distribution Analysis (ISO 4406 or NAS 1638)

3) Maximum Particle Size Analysis (ISO 4407).

This post will discuss the second method (above).

Particle Size Distribution Analysis (ISO 4406 or NAS1638) 

Particle Size Distribution Analysis is a reporting method to gauge both the size and number of contaminant particles in a calculated quantity of hydraulic fluid.  A fluid sample is either taken directly out of a hydraulic system or a known quantity of fluid is used to dislodge contaminants out of a hydraulic component. This fluid is run through a particle counting instrument to size and count contaminant particles.

These particle ‘counts’ can then be normalized by comparing the total component volume and to a corresponding ISO 4406 ‘code’ level of particle contamination. Levels of five and 15 microns of contamination are reported on a logarithmic scale corresponding to and ISO 4406 ‘code’ for the number of particles greater than or equal to these respective sizes per milliliter of fluid.
 


 

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Hose Cleanliness – affects Valves, Pumps, System cooling

Monday, October 24, 2016

posted by Brent at 1:03 PM 0 comments


Valves: Microscopic contamination (similar to erosion) can mill away tolerances which are used for sealing purposes. On spring centering valves, the debris may get caught between the valve and the wall surface. The contamination will cause the slowing down of the motion of the valve or causing sluggish or adverse mechanical actuation.

Abrasive particles enter the clearances between moving parts they score and hone the surfaces to greater tolerances. As these tolerances broaden, system performance is compromised by pressure losses incurred due to fluid leakage from high to lower pressures.

The worst occurrence is when particles that are greater than or equal in size to the orifice openings become wedged between the two surfaces. The contamination may cause wear to occur or it may cause the system components to seize.

Pumps & drives: Microscopic contamination can mill away material, creating leak points. These leak points rob the hydraulic system of pressure and cause poor responsiveness.

System cooling: Working fluid may not flow through to remove contaminants generated from metal to metal contact when passages become blocked. Lower flow rates mean greater heat buildup in systems and thermal breakdown of the working fluid.

 

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