Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/544388
"When someone says an oil flush is needed on a gas or steam turbine or a compressor, what does it mean? How would you do it? Or would you call in an expert to perform the oil flush?" An oil fl ush generally involves the internal cleaning of a machine with the use of a fl uid as the cleaning medium. While this sounds like a simple task to accomplish, problems can arise for which you should be prepared. There are several factors to consider when beginning an oil fl ushing project. Understanding how the oils being used interact with each other is paramount to the success of this procedure. In most cases, a fl ushing fl uid will be utilized. If the equipment manufacturer has oil fl ushing procedures, they should be consid- ered during this process. ASTM D6439 describes a successful oil fl ush as being when "clean pipe and system components are obtained in a minimum of time and with a minimum of effort." Therefore, the goal should be to effi ciently remove the old oil in a timely and cost- effective manner. The same ASTM standard also recommends a high oil velocity, at least two to three times the normal system velocity, for a successful oil fl ush. This is consistent with many procedures written by experts on this topic. Turbulent fl ow through the system removes the majority of oil left in gathering places. Some compo- nents may be too sensitive for a high-velocity oil fl ush. These components should be bypassed and cleaned by other means. The fl uid used for oil fl ushing is another point for consideration. A fl uid that won't react chemically with the oil it will be replacing should be sought. Incompatibility between these fl uids can form particulates that can be deposited throughout the system. After fl ushing, displacement oil should be used to remove any remaining fl ushing fl uid. The displacement oil must be compatible with and approximately the same viscosity as the operating charge to be installed. Flushing fl uids and oils should also be heated to maximize their ability to fl ow and absorb/dissolve contaminants within the system. Many different types of oil fl ushing proce- dures can be used. Hydroblasting is becoming more prevalent. In this type of oil fl ush, water is used in high velocities to spray the inside of the machine to clean and purge the system of oil and other contami- nants. Dry, clean and compressed air is then introduced to push out the water and dry the system. The new oil is then introduced. This, coupled with traditional oil fl ushing techniques, makes the process more reliable. A variety of companies specialize in the fl ushing of complex machine systems. Depending on the complexity of the oil fl ush or the manpower available to properly fl ush a system, these compa- nies offer a great alternative to utilizing onsite labor. Remember, a proper oil fl ush is very important to the health and reliability of a machine and should always be done with the sensitivity of the machine's components in mind. If you have a question for one of Noria's experts, email it to editor@noria.com. www.machinerylubrication.com | July-August 2015 | 49