The Challenge of Keeping Hydraulic Equipment Clean
Hydraulic equipment manufacturers are working round-the-clock to be the first to bring new 'must have' technologies to the market and fluid manufacturers are in test labs around the globe developing new solutions and preparing for the challenges of tomorrow. Betsy, Brian and Dave from the Lubrizol Corporation delve into details.

The one constant in any industry is change. People around the globe are striving to find better ways to do just about everything. Businesses want to improve the bottom line by becoming more cost effective, more productive and by staying one step ahead of the competition.

This is the universal motivation that drives innovation, but progress can't happen in a vacuum. One innovation can lead to another and ultimately demand that an entire industry keep pace.

The field of hydraulics is synonymous with movement. Beyond the 'movement' created by fluid power itself, the industry has made significant technical advances in recent years, with many innovations being developed in response to demands for increased performance from end-users.

Hydraulic equipment manufacturers are being asked by end-users for smaller, more powerful solutions and any resulting change in the design has a domino effect in the industry. New designs mean that manufacturers need to re-tool production facilities, parts manufacturers and mechanics have to keep up with the changes and hydraulic fluid and additive producers must solve a multitude of new performance challenges created by the continued advances in hydraulic equipment.

New technology, new challenges

One unwanted consequence of today's smaller but more powerful equipment is a significantly harsher operating enviro?nment for hydraulic fluids. As reservoirs are smaller and hold less fluid, it is forced to circulate through the system more rapidly, which means that the fluid has less residence time. This situation is significant for a variety of reasons.

Fluids require 'down time' to allow entrained air to escape and foam to collapse, both of which increase the compressibility of the fluid, resulting in reduced power transmission. Also, the equipment operator will notice that the controls no longer respond crisply and will have a 'spongy' feel when moved.

During compression, the air bubbles undergo a significant increase in temperature, resulting in oxidation of the fluid around the bubble (to the point of creating soot). When the pressure is great enough, the bubbles finally collapse against the metal parts, causing localized cavitation or erosion of the metal. In addition to the pump damage, these negative outcomes also cause shorter fluid life and the rapid development of one of the leading causes of hydraulic system failure, varnish.

Varnish and sludge cause deposits on valves, creating poor system response. Varnish also results in blocked filters and increased valve and pump wear, as well as diminishing a machine's overall effective?ness and performance.

End-users not only expect improved hydraulic technology, but also effective solutions to any issues that result from the development and use of that technology, such as more regular system cleaning and parts replacement due to increased varnish, heat, and pressure. However, they can't afford to shut their equipment down repeatedly to clean it or to replace parts more often.

Rising to the challenge

To help combat the issues that accompanied this new, smaller technology, the industry turned to hydraulic fluid manufacturers for a solution. The problems resulting from varnish, together with increased temperature and pressure, all needed to be dealt with in order for the new equipment to perform up to expectations. The hydraulic fluids that were available at the time were not effectively addressing the problems related to modern hydraulic technology, so a new solution was needed.

Global fluid manufacturers have answered the call and developed a system cleaner that can be added to a working fluid at a concentration of up to 20 percent while the equipment is running. Consequently, the downtime associated with system cleaning is significantly reduced and the hydraulic machinery is idle only for the time needed to drain, flush and refill the equipment.

Also the need for expensive valve replacement is eliminated and cleaning costs are greatly reduced as the parts are cleaned in situ. Productivity remains high because cycle times don't slow down as a result of the system being dirty.

In addition to its ability to clean equipment while running, the new cleaning technology can also be used in a static bath. The cleaner is not solvent-based so health and safety issues (often a concern for static bath solutions) are also reduced.

Lab testing

Lab tests were conducted on hydraulic pumps that had run for 1000 hours under severe operating conditions and had built up significant varnish. The new system cleaner was added to the used hydraulic fluid and allowed to circulate over a varnished valve taken from a piece of equipment. After 7 hours of circulation time, the previously varnished valve looked pristine with almost no trace of varnish left.

To test the cleaner's performance in a bath, heavily varnished spool valves were submerged in an oil-diluted solution of the cleaner, which was kept at room temperature and not circulated. After just 48 hours the varnished equipment looked like new and no scrubbing was required.

Field testing

Field tests were also conducted at an injection moulding machine shop where machines operate under extreme conditions. Oil samples and parts were removed and analysed. The parts were also photographed before the start of the trial.

Once the parts were refitted to the machine, a proportion of the system's hydraulic fluid was replaced with an equi?valent volume of the system cleaner and the machines continued to operate at their normal high production rate. During the 48 hour test, oil samples were taken at set intervals and once complete, the parts were removed and photographed again. The results were dramatic, with the dirty parts looking like new after the test period, which reinforced the results from the lab testing.

During the cleaning process there may be a need to change filters because of the quantity of varnish and other contaminants being flushed out of the system, however this wasn't necessary in this particular trial.

Cost savings

Extending the life of servo valves alone provides a tremendous cost saving as the average cost to clean or replace them can be in the region of $ 2,000 - 3,000 (Rs 98,000 - 147,000) per valve.

In addition to the cost, productivity is also a primary concern for end-users. After the system cleaner is used, a newly developed anti-wear hydraulic fluid technology can be added to the system to keep it clean for extended periods, allowing for ongoing equipment productivity and protection. This fluid also delivers excellent wear, rust and corrosion protection and outstanding filterability.

Varnish is polar, and thus, it has an affi?nity to metal. When varnish is created in the?se harsh environments, it will be at??t?ra?cted to, and then build up on, metal parts This additive technology works by suspe?nding contaminants in the fluid and preve?nts varnish from adhering to metal surfaces.

In laboratory hydraulic pump testing, signs of varnish are evident in the reservoir and on moving parts after only 500 hours of operation using a standard anti-wear hydraulic fluid- but this new hydraulic fluid technology prevents varnish even after 1,000 hours of stressed use.

Working towards tomorrow

The hydraulics industry is dynamic. Companies that rely on hydraulics will continue to think of new ways to get things done. Hydraulic equipment manufacturers are working around the clock to be the first to bring new 'must have' technologies to market and fluid manufacturers are in test labs around the globe developing new solutions and preparing for the challenges of tomorrow.

The Lubrizol Corporation, a Berkshire Hathaway company, is an innovative specialty chemical company that produces and supplies technologies to customers in the global transportation, industrial and consumer markets. These technologies include lubricant additives for engine oils, other transportation-related fluids and industrial lubricants, as well as fuel additives for gasoline and diesel fuel.