Grease Overview: How to Pump Grease
What Is Grease?
Although grease can appear solid in many applications, it functions as a lubricating fluid applied to components. Its consistency varies widely—from semi-fluid, similar to oil, to hard, in which case it cannot flow and may leave permanent indentations.
Grease is formulated from an oil base with thickeners and additives to achieve the required consistency. Unlike conventional viscosity measurements, grease is classified using a scale developed by the National Lubricating Grease Institute (NLGI), which ranges from 000 to 6.
Pump Options for Grease Transfer Applications
Grease pumps generally take one of two forms. The first requires the pump to be immersed within the container and uses a follower plate to level indentations in the grease caused by the pump, ensuring the pump always has a flooded suction. A follower plate is used together with a drum cover.
The second form of grease pump is a slow-moving positive displacement pump with a flooded suction. Grease is typically applied through a grease pump gun or nozzle to equipment requiring lubrication.
What to Consider When Selecting a Pump for Grease Transfer
Pumping grease in industrial applications requires careful consideration of several factors to ensure optimal performance and long service life for both the grease and the pumping equipment. Viscosity, temperature, and pump compatibility are among the key considerations that engineers and maintenance personnel must take into account.
Viscosity: Viscosity plays a crucial role in the pumping process because it directly affects the flow characteristics of the grease. Grease viscosity varies depending on factors such as base oil type, thickener type, and additives. Choosing a pump with the appropriate viscosity rating ensures efficient pumping without placing excessive strain on the equipment, causing recirculation within the unit, reducing output flow, or compromising the integrity of the grease. It is essential to match the grease viscosity with the pump’s capabilities to maintain consistent flow rates and prevent issues such as cavitation or pump wear.
Temperature: Grease viscosity is highly sensitive to temperature changes, with viscosity typically decreasing as temperature increases. When operating in extreme temperatures, it is important to select a pump that can handle the anticipated temperature range without affecting its performance or the quality of the grease. In addition, some greases may require preheating or cooling to achieve the desired viscosity for pumping, which may necessitate specialised equipment such as heating jackets on pumps or systems, or trace heating, to regulate temperature effectively.
Type of Grease: Selecting the correct pump for the type of grease being pumped is essential to prevent contamination, degradation, or chemical reactions that could compromise the performance of both the grease and the pump. Different types of grease contain various additives and thickeners that may react unfavourably with certain pump materials or components. Conducting compatibility tests and consulting with grease manufacturers can help identify the most suitable pump materials and construction for the specific grease being used.
Maintenance: Regular maintenance and monitoring are essential for ensuring the efficient operation of grease pumping systems, so the location of the pump within the processing plant and its accessibility need to be carefully considered. This includes inspecting pump components for wear or damage, monitoring grease quality and consistency, and adjusting operating parameters as needed to maintain optimal performance.
By carefully considering viscosity, temperature, and pump compatibility, industrial operators can maximise the reliability and productivity of their grease pumping operations while minimising downtime and maintenance costs.
