In 1927, Carl Norgren recognised the importance of the controlled introduction of lubricant when he invented the automatic airline lubricator. It seems contradictory that we discuss the removal of oil as a contaminant in other articles, but now outline the introduction of oil! However, the important distinction is the word controlled. In this article, we will introduce the types of lubricator available to suit different applications and pneumatic circuits.
What is a Lubricator?
A lubricator sits upstream from the air tool or component and provides a continuous stream of atomised oil to the points of use; in this way the lubricant provides much more effective and longer-term protection of the friction surfaces. It is worth noting that while many IMI Norgren products are self-lubricating, once a lubricator is added to the line, it must be used continuously; it will be damaging to the components to switch the lubrication 'on and off'.
How does a Lubricator work?
Air pressure in the bowl forces oil from the reservoir up a syphon tube into the site dome. An adjuster in the site dome allows the oil drip rate to be set; many site domes gives all-round visibility to aid drip-rate setting and control the level of lubrication. The set amount of oil is then atomised by the air flow and passed downstream. We are still quite unique in offering both an oil-drop and a micro-fog (see more below) lubricator. In the micro-fog version, the oil drops are further atomised to form a fine mist.
How do I select a Lubricator?
There are some key considerations in selecting a lubricator:
- Flow rate - the flow rate required for the level of lubrication will be an important consideration. A flow sensor can provide a nearly constant oil/air ratio over a wide range of flows.
- Type of component/system complexity - this will determine which type of lubricator is best suited; this is covered in more detail below
- Operating pressure - this will determine which bowl type is best matched to the application. Safety should always be in mind. For example, our new Excelon Plus has a unique double safety bowl lock, with an audible bowl clip.
Types of Lubricators
As stated above, IMI Norgren is one of the few suppliers that can offer both an oil-fog and micro-fog lubricator:
The oil-fog lubricator generates a fairly coarse mist of around 100 microns; all of the oil drops seen in the site dome pass into the air stream.
The micro-fog lubricator has a unique micromist fog generator built into the unit creating very fine mist particles of less than 2 microns. Around 10% of the oil seen as droplets in the site dome passes downstream as a mist, the remainder falling back into the oil reservoir.
Both units offer either a guarded polycarbonate bowl (maximum working pressure 10 bar) or a metal bowl (maximum working pressure 20 bar) with a prismatic sight glass. Both lubricator types are available from G1/4 to G3/4 as standard, with an NPT option.
Typical applications of Lubricators
By definition, droplets in the oil-fog lubricator are bigger and, thus, heavier. This is ideal where heavier lubrication is required, for example with slow moving, large bore cylinders, air motors and air tools. The air run, to the tool or component, should be over a short distance and either on a level or downhill. One benefit for this type of lubricator is that it does allow for the oil reservoir to be filled whilst the system is running.
Conversely, the mist from the micro-fog lubricator is suspended in the air flow and these are suited to complex systems, multi valve and cylinder applications and manifolds. It will provide lubrication over long distances and for up-hill and complex pipework; this provides optimum protection for multiple components. Micro-fog allows very fine control, ensuring that systems are not over-lubricated – a common problem with complex pneumatic circuits. They are perfect for small, rapidly moving applications.
At this point, it is important to mention start flow for a lubricator. There is a finite time for the oil drops to collect and become atomised and pass downstream. This can be critical for rapidly cycling valves and the micro-fog lubricator is much better suited to these applications having a much shorter time to operation.
Do I need anything else to make a Lubricator work?
Depending on application, the lubricator is likely to be part of a system with other components, for example, a filter, regulator (or filter regulator) and shut-off valve. Mounting brackets will be required, as will tubing and fittings. Various accessories are available, such as porting blocks and a quick fill nipple. Service kits are also available to ensure for regular maintenance.