Oil Types: How to Pump Oils
Oils vary widely in viscosity, ranging from just a few centistokes (cst) to over 1500 cst, especially in the case of Heavy Fuel Oil (HFO). The viscosity of oils, influenced by their type and temperature, is often described by a viscosity index, indicating how viscosity changes with temperature. A low viscosity index suggests that oil is significantly impacted by temperature fluctuations. 
Oils serve multiple purposes, acting as lubricants, fuels, and heat transfer mediums. Their high boiling points and capacity to retain heat make them ideal for such applications.
Oils are typically accompanied by a datasheet detailing the viscosity at a specific temperature and care must be taken to ensure this is the temperature of the operation as due to the thickness of some oils a positive displacement pump may have to be used.
Centrifugal pumps may require the oil to be heated to be able to pump and flow rate and pressure is affected greatly by viscosity with a centrifugal pump.
Positive displacement pumps are best for viscous oils as they are largely unaffected by viscosity and with thicker oils flow rate and pressure increases rather than the opposite with centrifugal pumps.
Pump Selection Considerations for Pumping Oil in Industrial Applications
Selecting the right pump for pumping oils in industrial applications is crucial for maintaining efficiency, reliability, and safety in operations. Several factors must be considered to ensure optimal performance and longevity of both the pump and the oil being handled.
Viscosity Compatibility: Oil viscosity varies depending on factors such as temperature, type of oil, and additives. It is essential to choose a pump that can handle the viscosity range of the oil without causing excessive recirculation, low pressure or flow issues. Positive displacement pumps, such as gear, screw, progressing cavity or diaphragm pumps, are often best suited for handling oils with varying viscosities.
Material Compatibility: The materials used in the construction of the pump must be compatible with the type of oil being pumped. Some oils may be corrosive or abrasive, requiring pumps made from specific materials such as ductile iron or stainless steel or corrosion-resistant alloys to prevent degradation or contamination. Some oils may contain additives which can destroy certain polymers historically used with oils. Compatibility testing and consultation with pump manufacturers can help determine the most suitable materials for the application.
Temperature Considerations: Oils are sensitive to temperature changes, which can affect their viscosity and flow characteristics. Pump selection should account for the operating temperature range of the oil, ensuring that the pump can handle both high and low temperatures without compromising performance. Additionally, pumps may require a heating jacket or cooling systems to maintain the oil within the optimal temperature range for pumping.
Flow Rate and Pressure Requirements: Understanding the required flow rate and pressure for the application is essential for selecting the appropriate pump size and configuration. Centrifugal pumps are commonly used for applications requiring high flow rates at low viscosity where the pressure loss is unlikely to change, while positive displacement pumps are preferred for applications requiring precise control and are more likely to handle any changes in flow and pressure.
Shear: Pump shear can create emulsification of oils if pumped with other liquids which do not dissolve in oils. Choosing a pump with lower shear capabilities can minimise the mechanical forces exerted on the fluids, reducing the likelihood of emulsion formation. Conversely, selecting a pump with high shear characteristics may promote emulsification, leading to operational inefficiencies and potential product quality issues. Thus, matching the pump's shear intensity to the specific application is essential for optimal performance and product integrity.
Maintenance and Reliability: Consideration should be given to the ease of maintenance and reliability of the pump. Choose pumps with robust construction, easy access to components for maintenance, and a proven track record of reliability in similar oil pumping applications. Regular maintenance, including lubrication and inspection of pump components, is essential for ensuring continued performance and preventing unexpected downtime.
By carefully considering factors such as viscosity compatibility, material compatibility, temperature considerations, flow rate, pressure requirements, and maintenance needs, industrial operators can select the most suitable pump for pumping oils in their applications, ensuring efficient and reliable operations.
To discuss your requirements and explore a pump solution that meets your needs get in touch with our application specialists.
