Executive Ship News Bulletin

ENB History | Home

Jan 2008 | Page - 5

[<<Prev] 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 [Next>>]

Hydraulic Oil Particle Contaminations

How to deal with?

Over 90% of catastrophic failures are the result of abrasive wear that causes the pumps, valves etc to fail. Part of the role oils and hydraulic fluids play is to coat these parts, helping to reduce friction and abrasive wear. Yet these same "protective" oils may be contributing to a catastrophic failure. Over time, the oils themselves are contaminated with particles that can contribute to wear on the machinery.

These particles come from a wide variety of sources, including particles left on new machinery or parts by the factory, dirt and dust from the outside environment, wear and tear on the machinery and parts, and even contamination in the oil itself. Over time particles from all these sources build up in the oil, and eventually can cause temporary or permanent equipment failure.

The balance of when to change the fluid, filters, or other parts to avoid down time and excessive repair costs versus the cost of maintenance and replacement is delicate. A wrong decision can result in unnecessary maintenance, increasing operating costs; on the other hand, delaying maintenance can result in a catastrophic failure, increasing ownership costs.

Lubricant Data	date xxxxxx	date xxxxxx	date xxxxxx
ISO Code (4/6/14)	22/19/12	22/19/15	20/17/12
Particle Count >4u	33894	22862	8519
Particle Count >6u	3916	3541	974
Particle Count >14u	33

Table 1: A Sample of Standard Oil Analysis

These particles can cause many types of failures:

1.	The particles can clog small orifices that control critical hydrostatic balances, causing a catastrophic failure.
2.	Particle contamination can also cause moving parts to completely lock.
3.	The particles themselves may cause additional wear and tear on the machinery and parts, creating more particles that contaminate the oil.
4.	Each of these problems can cost thousands of dollars in damage if not prevented.

One way to reduce the particle contamination level in the oil is through the use of filters. The filter is placed before the critical part to prevent the particles from reaching the part, damaging it. Unfortunately, over time the filters become clogged, and prevent the oil itself from reaching the part. Additionally, the filters can develop holes, allowing the particles through to the part they are intended to protect.

To gain a complete understanding of the condition of the oil, and the parts and machinery themselves, it is vital that the oil be regularly monitored and the results recorded. Over time, these results can be trended, and used to create effective maintenance schedules. Particle counters can also be used to check the efficiency of the filters and schedule filter changes.

In addition to aiding maintenance scheduling, particle monitoring can identify a sudden increase in the number of particles in a sample. This sudden increase can indicate an imminent failure that might be avoided by unscheduled maintenance. In the long run, performing this maintenance before the failure occurs will save thousands of dollars in repair costs and unscheduled downtime on the equipment.

How to interpret the results of particle count?

One of the most commonly used standards is IS04406.

Once a sample has been analyzed the IS04406 code can be applied. The method, which is the most commonly used, involves simply reading the code level off the table. First the code for 4 µm is determined, then the code for 6 µm & than lastly for 14 µm ; the numbers are written separated by a slash. A sample of standard Oil Analysis has this information for hydraulic oils as shown in Table. 1.

Article Compiled by Mr. Venkateswara Rao Katta, Technical Superintendent