Extend Machine and Lubricant Life
   Through Contamination Control
September 8, 2005

In This Issue:

Oil Filter Ratings Explained

Keeping Gearbox Oil Clean

Water Exclusion is Difficult

 

Oil Filter Ratings Explained

"What does industry consider the standard in regards to filter efficiency? When I hear that a filter is rated at 1 micron, does that mean it is 100 percent efficient at that micron size?"

Filter ratings are an often misunderstood area of contamination control. The most commonly used rating is the Beta ratio, which is defined as the ratio of the number of particles upstream of the test filter versus the number downstream, greater than a given size. Using the Beta ratio, a 3 micron filter with a Beta 75 rating, will have on average 75 particles larger than 3 micron upstream of the filter for every one 3 micron or greater particle.

The efficiency of the filter can be calculated directly from the beta ratio since the % efficiency is simply (beta-1)/beta x 100. A beta 75, 3-micron filter is thus said to be 98.66% efficient at removing 3 micron and larger particles. It is important to note that a change in the beta rating from 75 to 200 at the same micron rating represents an increase of less than 1% in efficiency, but the beta 200 filter is more than 3 times more effective at removing 3 micron and larger particles than the beta 75 filter.

Caution must be exercised when using beta ratios since they do not take into account field operating conditions such as pressure surges and changes in temperature, which can affect real life performance. A filters beta ratio also does not give any indication of its dirt holding capacity, the total amount of material that can be trapped by the filter throughout its life, nor does it account for how the capture efficiency changes over time. Nevertheless, beta ratios are an effective way of gauging the expected performance of a filter.

The ISO standard for Multi-pass filter testing (ISO 16889) has changed to require filter manufacturers to determine the average particle sizes which yield Beta ratios equal to 2, 10, 75, 100, 200, and 1000, again using the multi-pass test stand approach. The new standard gives a better interpretation of a filter's overall performance.

Of course, regular monitoring of fluid cleanliness using ISO particle counting should be used to determine the efficiency of the filter in actual field conditions.

Keeping Gearbox Oil Clean

"I notice that the ISO cleanliness level doesn't change much after changing the oil in my gearboxes. Shouldn't the oil be cleaner after the change?"

Most gearboxes are drained on a quarterly, semi-annual or annual basis - usually to eliminate contaminants. Typically, five percent or more of the old lube is left in the gearbox. If the oil is not drained shortly after shutdown, the sludge and contaminants will accumulate in the bottom of the sump and remain with the residual oil. When the box is refilled with lubricant and restarted, the contaminant is re-suspended, and the oil change fails to achieve its objectives. Also, the new oil may not be clean if it is not prefiltered.

Consider the following alternatives:

1. Drain the oil within 15 minutes of shutdown and pre-filter the new oil.

2. Instead of draining the oil, periodically filter the oil with a portable filtration cart while the machine is operating. Sample and analyze the oil periodically to determine if it needs to be changed. This strategy will reduce your overall cost of maintenance and extend the life of the gearbox, and requires little up front investment.

3. Install full-time filtration on the gearbox and sample and analyze the oil periodically to determine if it needs to be changed. This strategy will also reduce your overall cost of maintenance and extend the life of the gearbox, but requires some up front investment.

Alternative 1 helps, but alternatives 2 and 3 are real winners. Most scheduled oil changes can be eliminated with the one-two punch of filtration and oil analysis. This strategy reduces lubricant and labor costs – and the fact that your gearboxes will last longer is a major bonus. Plus, the maintenance of the fluid can typically be performed during run-time, shrinking the task list during scheduled outages.

 


Water Exclusion is Difficult

From the book Filtration Technology

Water is a common contaminant in hydraulic and lubricating systems. Moisture can enter these systems at several points:

* Through reservoir breather caps in humid air. System fluid absorbs some of this moisture, while some is condensed on the inside surfaces of the reservoir.

* Through worn seals. Besides humid air, coolant and cutting fluid sprays can enter hydraulic systems through worn rod seals as the cylinder moves. In lubricating systems, these water-based fluids can enter through rotating shaft seals on pumps, machine tool spindles and gear boxes.

* Through heat exchangers. Worn and damaged heat exchangers can allow cooling water to leak through seals and ruptured lines into the oil system, and vice versa.

* In new oil. An oil barrel stored outside in a vertical position is likely to collect rainwater around its bung. With changes in temperature, some of this moisture will be sucked into the barrel. Eventually, this water enters the system fluid when the reservoir is filled.

More about the book Filtration Technology

Resources

 


Remove submicron particulate
and prevent tar and varnish with ASL's patented Electrostatic Fluid Purification Systems.
Request information today!

 


Extend Machine Life
and transform your lubrication program to best practice with easy-to-use Oil Safe® containers from PdMA, authorized distributor.

 


In-line Measurement of Moisture in Oil
Vaisala HUMICAP®
Hand-held MM70
Measurement independent of oil type, age, temperature
E-mail
1-888-VAISALA (824-7252)

 


Certification means proven knowledge.
Analysts delivers what others promise. For you. For all our customers.

 


Training Calendar

SEPTEMBER 2005

Machinery Lubrication I
19-21 Chester United Kingdom
20-22 Las Vegas, NV
22-23 Gdansk, Poland
20-21 Monterrey, Mexico

Machinery Lubrication II
22-23 Monterrey, Mexico

Oil Analysis I
26-28 Chester, United Kingdom
28-30 São Paulo, Brazil

Oil Analysis II
14-15 Neuquen, Argentina
20-22 Las Vegas, NV

Effective Contamination Control
21-22 Point Lisas, Trinidad

Effective Mobile Equipment Lubrication
20-22 Boksburg, South Africa

Oil Analysis – The Complete Course
14-16 Bangkok, Thailand

OCTOBER 2005

Effective Mobile Equipment Lubrication
3-5 Chester, United Kingdom

Lean Manufacturing 2005
4-5 Cleveland, OH

Machinery Lubrication I
3-4 Harare, Zimbabwe
11-13 Portland, OR
24-27 Jwaneng Mine, Botswana

Machinery Lubrication II
| 5-6 Harare, Zimbabwe
20-21 Gdansk, Poland
26-27 Houston, TX
Oct 31 – Nov 1 Sydney, Australia

Oil Analysis I
10-11 Pretoria, South Africa
17-18 Valencia, Spain
17-19 Selangor Darul Ehsan, Malaysia
24-25 Antofagasta, Chile
25-27 Houston, TX
26-27 Buenos Aires, Argentina

Oil Analysis II
11-13 Daegu, Korea
12-13 Bogotá, Colombia
12-13 Pretoria, South Africa
19-20 Valencia, Spain
26-27 Antofagasta, Chile

Oil Analysis – The Complete Course
4-6 Gdansk, Poland

Filtration Tips is published twice a month by:
Noria Corporation, 1328 E. 43rd Court, Tulsa, OK 74105 USA. (918) 749-1400

Because results will vary widely based on a number of factors, Noria Corporation cannot warrant the results of any information within this e-mail.

© 2005 Noria Corporation

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