Compressor Lubricants and Compressor Lubrication
Cylinder and Packing Oil Recommendations
The following matrix shows recommended oil for a given discharge pressure and type of gas. These lubrication recommendations are general guidelines. If the recommended lubricants or flow rates do not appear to work adequately, flow rates and/or lubricant types may need to be changed. Please contact the lubricant supplier for specific lubricant supplier for specific lubricant recommendations.
Base Rate Calculations
There are many different ways to calculate the amount of oil that is injected into the cylinders. Most manufacturers historically have used a specific base amount of oil and factored that by the diameter of the cylinder or piston rod. Other components of the calculated lubrication rate may include piston stroke and speed. The total amount of oil has been specified by a total volume of oil or by the number of drops per minute. B far, the more accurate measure for lubrication is the volume of oil.
Drops per minute only provide the correct amount of oil at a specified temperature. If the temperature is colder or hotter, the size of the drop can change dramatically. This may either inject into the system. The smaller drop of hotter lubricant will not provide the same lubrication as the larger drop of colder lubricant.
A total volume of oil such as pints per day is more accurate because it will inject a consistent amount of oil into the system regardless of the temperature. A base rate set by a number of pints per day per inch of bore diameter is one common calculation method to determine the total amount of oil required by that point. The base rate is determined by:
Base Rate (pints per day) x Bore (inches) = Total pints per day at full rated speed
A second calculation is then needed to determine the cycle time for a given divider block and to modify that rate for reduced speed.
Another calculation method injects one pint per day per 2,000,000 ft2 of cylinder surface area.
(Bore x Stroke x rpm) ÷ 31800 = Pints per day
Again, a second calculation is needed to determine the cycle time for a given divider block.
Once the total pints per day are known for each injection point, the proportion of the total is used to determine the size of distribution block needed. Determining the proportions of the blocks needed is done by using ratios of the required rates and then selecting a block that provides the closest match. Usually a range of 90% to 115% will allow for selection of a block.
Finally, once all the blocks are known, the cycle time can be calculated by the following equation.
Cycle Time = (6 x Sum of all blocks) ÷ Total Quantity of Oil
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