This is the final part of our FRL series, which stands for filter, regulator, and lubricator. In this post, we will discuss the pneumatic lubricator.
So, what does a lubricator do? A pneumatic lubricator sprays micro-particles of lubricator oil into the airflow to provide fluent lubrication. The purpose of lubricating pneumatic devices is to prevent abrasion caused by solid friction sliding movements, which improves durability, reduces perturbation resistance, and improves efficiency. It also lubricates seals to reduce wear and tear and prevents air leakage.
There are various kinds of pneumatic lubricators, but the most popular type is the full-bore lubricator. This type is installed at the end of the filter or pressure-reducing valve to send all oil particles to the other parts of the FRL. Oil particles are easily attached to the inner walls of pipes when they are several microns or larger. If long pipes are used, most particles attached to the walls will move slowly move with the airflow that is generated with the conversion of the directional control valve. (We will talk about directional control valve in a separate article.)
The selective lubricator selectively extracts particles that are about 2μm or smaller and mixes them into the airflow. This type is mostly used with longer pipes where oil particles need to travel a long way. Nowadays, lubricators are not installed at each level, instead centralized lubricators are used with a special lubricator installed near the main pipe for centralized control.
Two Types of Pneumatic Lubricators
The two main types of pneumatic lubricator are
- Selective lubricator
The full-bore lubricator, shown in figure 1, comes in various configurations, but it is classified as either fixed or variable types, based on the method of generating pressure differences for the delivery of the lubricator. Both fixed and variable types feature a resisting body inside the main pipeline. The difference in pressures between the resisting body’s front and the back ends is used to push up the oil from the case to the piping and send it into the flow of air.
Figure. 1 shows the configuration of a full-bore pneumatic lubricator with a variable pressurizing device. This type of lubricator can lubricate during operations while the check valve blocks the main pressure when the lubricating cap is opened for lubrication.
Figure 2 shows a selective lubricator. In the image, the air supplied to the main body passes through the variable throttle tool to generate a pressure difference that pushes the lubricator oil up the lubricating pipe. When pushed up, the flow of the lubricator oil is adjusted by the adjust screw and is loaded into the pipe. Unlike the full-bore type, the selective type is designed to pass through a separate nozzle without being injected into the airflow. A portion of the airflow comes into the nozzle to spray the oil as small particles. As larger particles of sprayed oil drop down onto the surface, the particles float in the air and are conveyed to the rest of the lubricator.
In figure 3, the lubricator not only lubricates, but it can also cool the air. Because of the air being cooled, the lubricator is mostly used to lubricate bearings and gears.
Because pneumatic tools require large air consumption, their lubricators use variable-throttle tools that have relatively small resistance.
This concludes the components that make up an FRL. To learn more use the resources below.
More about FRLs
This is one of three articles about pneumatics components called FRLs. See the other FTL posts here:
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