Lube Oil System (LOS)

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A lube oil system is an essential part of large industrial machinery. Lube oil circulates through the system, ensuring that all moving parts are well-lubricated and protected. This helps to reduce wear and tear on the internal components, keeping your equipment running smoothly for years to come. However, it is important to understand what a LOS is, how it works, and some common problems that can occur to maintain it properly.

What is a Lube Oil System?

The term lube oil system also refers to lube skids or circulating oil systems. These systems provide continuous oil supply to various moving parts such as bearings, gearboxes, and blowers. Not only does a LOS provide a constant flow, but also it helps circulate hot lubricant away from machinery to cool. Typically, these systems utilize large reservoirs with capacities ranging from a few hundred gallons to thousands of gallons. Also, these systems use heavy-duty pumps that can handle continuous operation with a wide range of flow rates.

How to Use a Lube Oil System

Heavy-duty machinery, as well as factories that produce cement, sugar, paper, steel, and other materials, frequently employ lube oil systems. In any of the aforementioned facilities, there are generally several lubrication points. If these points are located in a cluster or close to each other, a centrally located lube oil system can feed all of the lubrication points.

The return lines from each of these locations go back into the lube oil system’s reservoir, which most facilities install in a basement or simply at a lower elevation than the equipment. This allows returning oil to flow by the force of gravity. To prevent returning oil from exerting back pressure on the delivery lines, every return line has a slant toward the lube oil system. Then, you can control each line’s pressure and flow by a group of control valves, depending on the system’s complexity.

The Main Functions of a Lube Oil System

Getting the right amount of oil into the equipment is a lube oil system’s primary goal. A secondary function is to aid in lubricant temperature control by either cooling or warming the lubricant before circulating back to your assets. Additionally, a LOS forms a loop and functions consistently without interruption until a filter needs to be changed.

What to Consider When Choosing a Lube Oil System


Typically, 35 psi (pounds per square inch) or less is the operating pressure. During startup, certain applications may need higher pressures, such as those designed to prevent metal-to-metal contact by suspending a bearing in lubricant

Flow Rate

Your flow rate must equal the total requirement of all the assets if the system supplies more than one. You can further control the flow rate for each asset at the delivery point with a needle valve.


Lube oil systems typically involve three types of filtration. As a first step, passive filtration takes place in the reservoir with a baffle. Secondly, when it passes through a mesh strainer. The final filtration happens before the fluid exits the system, usually with 23-micron filters.

Motors and Pumps

Different motors are available in various voltages, frequencies, and phases to meet the needs of different power sources. Most industrial motors are TEFC (totally enclosed, fan-cooled) and are safe to install in a variety of environments.

Piping and Reservoirs

Standard reservoirs are made of welded steel with heavy-gauge steel covers. A national pipe thread (NPT) fitting is usually used to join piping and fittings made of iron. To prevent corrosion, the entire system needs to be painted or coated.


Lube oil systems have many potential gauges that indicate operating conditions. These gauges include:

  • Pressure Gauge – to ensure the pump is operational and the bypass relief valve is working to prevent pressure buildup.
  • Liquid-Level Gauge with Thermometer – For monitoring lubricant temperature.
  • Piping Thermometer – Provides feedback on lubricant temperature after passing through a heat exchanger.
  • Differential Pressure Gauge – For measuring any pressure loss at filtration points.


Electronic controls can interpret the signals from switches to send data to monitoring stations, control how the unit operates, activate alarms, or shut down machinery. These could be switches for low-flow, temperature, or differential pressure.

Heat Exchangers

Bringing the oil’s temperature down before reintroducing it to the equipment is the function of a heat exchanger.

Immersion Heaters

An immersion heater raises the oil’s temperature by coming into contact with the oil in the system reservoir. This is incredibly useful in cold climates to reduce the impact of cold startups by warming the lubricant to an appropriate temperature.

Environmental Conditions

The environment around a LOS can have an impact on how well it functions. Design considerations should include altitude, temperature, and exposure to the elements.

Lube Oil Systems: A Key Component of Lubrication Management

When it comes to lube oil systems, there is no one size fits all solution. However, the value and service that the system can provide are quite consistent across every application. Having a continuous flow of lubricant and a system that manages the pressure and even the ideal operating temperature makes a substantial impact on asset health, reliability, life cycle, and uptime.

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