Reciprocating compressors are machines that raise the pressure of gases and then deliver them for use in several applications, including those associated with pneumatic, combustion, and gas-transmission processes. The primary purpose of a reciprocating compressor is to significantly increase gas pressure until it reaches the point where it can be utilized within an industrial facility. These machines are composed of many parts that require frequent lubrication for optimal performance.
This shows that compressors are used extensively in demanding applications such as oil/gas refineries, petrochemical plants, and natural gas pipelines. All these are possible due to the pistons driven by crankshafts within the compressors that deliver gases at high pressure.
As a result, reciprocating compressors require lubrication from time to time to maximize performance, minimize friction, and wear and tear of components and overall reduce repair costs.
Here’s what you need to know about the lubrication of reciprocating compressors.
Lubricating Reciprocating Compressors
Maintaining the appropriate lubrication of reciprocating compressors is of utmost importance regarding equipment reliability. Most reciprocating compressors operate non-stop or continuously, increasing multiple runtimes on wearing equipment components.
Lubricating reciprocating compressors, especially in terms of oil viscosity and type, can vary widely, depending on the desired discharge pressure and the type of gas to be compressed. Most reciprocating compressors only have three unique areas for lubrication:
- Cylinders, including piston rings, cylinder walls, piston rods, packing rings, and valves
- Packing, i.e., pressure packing and oil wiper packing
- Crankcase, including timing gears, bushings, bearings, crosshead guides, thrust plates, etc., in the drivetrain
Two separate systems efficiently lubricate these three distinct areas. The first system is an oil circulation structure that effectively lubricates the crankcase area. This particular system employs an oil pump to circulate oil from the pool of compressor lubricant that fills the machine’s crankcase to the numerous components within the crankcase.
The second is a force feed lubrication system – or ‘total loss’ or cylinder lubrication system – designed to lubricate the cylinders and pack via tubing. Operators need always to carry out cylinder feed rate studies when using this system. This is because improper feed rates can result in several problems, such as:
- High oil consumption
- Flash fires
- Premature valve wear
More often than not, the force-feed lubrication system uses the same lubricating oil – usually a gas engine oil – as the crankcase oil circulation system. Be that as it may, when the gas to be compressed is not exactly pipeline-quality natural gas and must be compressed above 1,000 pounds per square inch gauge (PSIG) in pressure, consulting your lubrication engineer for the ideal product recommendation becomes imperative.
The significant difference between these two systems is how the lubricating oil is utilized. The drivetrain reuses its lubricating oil several times before the fluid is eventually replaced. But the cylinder lube system only uses its lubricating oil once before it is entirely consumed during the compression process.
Therefore, efficiently using lubricating oil within the cylinder lube system is crucial when considerably minimizing operating costs while maximizing equipment reliability.
How Reciprocating Compressor Oil Works
Reciprocating compressor oil is primarily designed to serve only three essential purposes within the equipment. The first is lubricating every moving component within the reciprocating compressor so they can seamlessly work together without wearing or binding.
Secondly, the compressor offers an excellent means of cooling the machine by carrying heat generated within the equipment away as the oil cycles. This is crucial since the internal components can quickly get extremely hot during regular use. This causes the components to expand and contract intermittently.
Finally, many reciprocating compressors use oil to ensure super-tight seals by preventing gaps around gaskets and O-rings. If the cooling oil is not in place, the components will eventually seize against one another. When this happens, your system operates at maximum efficiency without losing pressure.
As soon as the oil starts breaking down, you may notice that your reciprocating compressor becomes far less efficient. This is because the oil no longer provides the same cooling, lubrication, and sealing level the system requires. This eventually creates hot spots and gaps where future severe damage could occur.
How to Choose the Right Reciprocating Compressor Oil
Now that you fully understand the primary purpose of the reciprocating compressor oil, the next step is to choose the ideal lubricating oil.
But choosing the ideal reciprocating compressor oil is a challenge in the park. This is because you will find myriads of lubricants available everywhere. You may even be tempted to think every compressor oil are all alike. But that is far from the truth.
When choosing the right reciprocating compressor oil, you must be extra careful. First, you need a lubricant with the ideal properties for cooling and lubricating your system. Unfortunately, many traditional oil products online and offline today need to possess the ideal properties and additives capable of cooling your system during operation.
These lubricating oils offer zero relief from the heat generated within the system during operation. They may also separate and even break down under extreme heat conditions. You will always be on your toes and forced to constantly change your reciprocating compressor oil to keep your operations running smoothly without downtime.
You must select a specially formulated lubricating oil that works with the refrigerant used in your commercial reciprocating compressors. These lubricating oils usually come with distinct labels that inform you they contain the additives your system needs for sludge control, cooling, foam control, and so much more.
Many commercial reciprocating compressors utilize refrigerants designed to only run with mineral oil. But the newer refrigerants can run with synthetic oils. The label on the specially formulated lubricating oil should also indicate it possesses high oxidation stability to prevent corrosion and rust.
Therefore, ensure you select the ideal lubricating oil that matches the refrigerant used in your system to ensure the proper lubrication of your reciprocating compressor.
Reciprocating compressors are machines that operate almost non-stop to deliver pressurized gas or fluid to appropriate areas. To do this effectively, they require the perfect lubricating oil to cool, lubricate, and ensure tight seals during operation.
The tips above should help you select the right lubricating oil for your reciprocating compressor, ensuring maximum efficiency.
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