There are many versions of the definition as stated by various associations and engineering groups. The definition also varies by industry and that makes it outside of the scope of this article. For the purposes of this article let us agree that we are talking about equipment or a system identified as critical to the manufacturing or processing operation and that provides direct safety or indirectly can cause a safety system to fail. In the maintenanceforums.com thread on the definitions, user: Lynn R states there is ambiguity as to the criteria associated with “critical” and what that means. It’s a fair statement that I agree with completely.
Pumps in many cases are firmly placed in the realm of what is considered critical and most pumps that I know of, or have been exposed to in many industries will in fact stop production or become a safety hazard if they are not in use…so we will consider them critical equipment, at least for the considerations here.
In a paper mill the pump is generally used to pump water and also to create vacuum. In an oil refinery they are used to pump sludge, oil, and gas to storage and around the facility. In food production they can be utilized to move raw materials from one process to another. In water treatment operations they move water through the entire process.
Lubrication of pumps is done in a number of ways based on the type of pump, the driver of the pump, and the configuration needed for continuous operation. One common denominator in all types of pumps are the bearings. These bearings can take the form of many styles or types and either be grease lubricated or oil lubricated. Most industrial applications utilize oil, which resides in the bearing housing itself. More typically the pump has a bearing housing which is in the form of a sump or tank if you will. The ideal level of lubricant to achieve the bearings life expectancy and for the equipment to run reliably is always the middle of the lowest ball or roller.
Viscosity is the most important factor when lubricating an industrial pump. The operating environment, duty, cycle and speeds have a direct impact on an oils viscosity. Most pump OEM’s recommend viscosity ranges and sometimes specific brands of lubricants based on what is considered “typical” operating environments. Keep in mind the lubricant is part of the design criteria of any piece of rotating equipment, in this case pumps. OEM recommendations should be used as a guideline only. Determining the correct oil for any application requires you to understand the operating environment and conditions which will have a direct impact on the oils viscosity. If you think about it in everyday terms, vehicles operating in colder climates require a lower viscosity fluid for the simple fact that lower temperatures tend to increase an oils viscosity.
In terms of plant operation the main purpose of an external oiler is to insure the correct oil level is maintained in the bearing housing. Other benefits to an external oiler allow maintenance and operations to visually inspect the level of oil and the condition. If the oil has a hazy or milky tint to it the typical cause is moisture ingression or if it’s dark and burnt looking the oil is most likely no longer suitable for use. Based on very harsh operating environments such as food and beverage plants which have water wash-downs, chemical and oil refineries which deal with outside weather conditions, and dust and paper mills dealing with severe moisture and particulate issues it is important to outfit the pump with the proper bearing protection aimed at mitigating the ingression of contaminants. A great option to control ingression is a closed system oiler and extreme environment desiccant breather. In situations where mild environments exist a vented oiler with a standard desiccant breather will work. Remember, lubricant selection and proper bearing protection is dictated in most part by the operating environment. The goal is to protect the integrity of the lubricant and maintain the correct level which is at the mid-point of the lowest ball bearing.
Case study after case study show that doing these simple things when lubricating your pumps can save you worthy amounts of time, resources, and capital when considering the life of the lubricant, equipment life, and cost of downtime. In a particular application, the cost benefit went something like this:
In a paper mill there were 100 pumps, which needed lubrication change out is every 6 months. The cost of changing this lubricant was $40,000 which included oil, labor hours, downtime, etc.. They were using the correct lubricant for the application and environment they were in but wanted to get more life out of the lubricant. Something had to change to achieve a different result. They installed a closed system oiler with an extreme environment breather at a cost of $350 per unit the customer was able to extend oil change intervals to 12 months. So for approximately a onetime cost of $35,000, a savings of $5,000 was realized in the first year. In year 2, 3, 4, & 5 the savings was $40,000 per year. Total savings over a 5 year period amounted to $165,000. Certainly a worth while investment in your critical asset care program. This is an over-simplified example, but one that plays out on a daily basis in facilities around the globe.