Leakage: Think About It!

I am one of the worst problems in industry.

• I have been around for many years and   am still going strong.
• I cost industry billions of dollars every   year.
• I am hazardous and even cause death.
• I am a cancer that continues to   spread.
• The cure was developed many years   ago.
• Engineers, Consultants, Technicians   and Mechanics foster my growth.

• Fortunately for me, ignorance, lack of knowledge, training and apathy,   prevail.
• I think apathy plays the major role starting with the very design of   machinery world wide.
• My name is LEAKAGE.

The solution:

The electric industry sought for and solved their leakage problem. There still are some occasions of electrical leakage but usually due to accident, ignorance or abuse. Knowledge and training have been emphasized on a daily basis and at all levels of academia. This education has made a difference; for example, it is a rare occasion for any one to search for missing or cracked insulation on a live electrical system with their hands. That obviously could result in serious injury or even death. When leakage does occur, for whatever the reason, the machine is IMMEDIATELY shut down. Electrical leakage is treated very seriously and promptly.

The solution to Fluid Power leakage is treated quite differently and has become more complex because of the lack of education and “on the job training”. Looking for leakage with your hands on a pressurized (live) system is equally as hazardous and costly as with electrical systems. Leakage should be dealt with very seriously and promptly.

Solving the problem is further complicated by the variety of indigenous port and tube connections. A quick review of the commonly used connections around the world reveals that there are eight different port connections and twelve different tube/hose connections.

Leakage is no longer acceptable in world class products. Proliferation, besides limiting availability and increasing cost, increasing cost, increases leakage potential through misapplications. Therefore, the challenge facing the fluid power industry is two fold – eliminate leakage and minimize proliferation.
This challenge has been met through a very intensive and cooperative effort by the member nations of sub-committee 4 of the ISO Technical Committee 131 (ISO/TC131).

Five ports, four threaded and the four bolt flange, and four tube/hose connections have been standardized. The threaded ports and tube/hose connections are paired in the ISO 8434 series of fitting standards as defined below.

To minimize proliferation in port usage and promote leak free connections, the sub-committee strongly endorses use of ISO 6149 port for all new designs by including the following statement in all port standards.
For threaded ports and stud ends specified in new designs in hydraulic fluid power applications, only ISO 6149 shall be used. Threaded ports and stud ends in accordance with ISO 1179, ISO 9974 and ISO 11926 shall not be used for new designs in hydraulic fluid power applications.

This work by ISO and SAE was an enormous task and the importance cannot be over emphasized. Leak free Fluid Power systems have been the objective for many years. Emphasis and promotion of these standards is an industry obligation. This is extremely important because today’s reality is that there are still eight port connections and there are eleven tube/hose connections in use.

Since there are many different similar looking connections, especially on the port side, a great deal of confusion and mixing of components is inevitable resulting in a cancerous spread. Technicians must be able to identify and distinguish one from another.

Obviously the solution is complex and requires the concerted effort of anyone and everyone associated with fluid power from Academia to the Engineer/Consultant to the end user.

In the near future the Fluid Power Society will be releasing “Conductor & Connector” Certification. It will cover the fabrication of hose and tubing assemblies. This is a certification sponsored and supported by SAE.
Success depends on you.

Written By: R.F. Hanley

Reprinted with permission from Fluid Power Journal

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