A lubricator is a device located downstream of the air compressor. It usually consists of a small reservoir with a supply of lubricating oil and a dosing mechanism that dispenses a specific amount of oil into the air stream. The oil reduces the wear of highly stressed pneumatic drives and prevents the formation of rust and moisture. The Festo range not only includes individual accessories such as lubricators, but also complete service unit combinations. Depending on the area of application, they also offer other components for a service unit such as soft-start valves, filter regulators, filters, on/off valves and branching modules.
Oil is pumped from a reservoir and released into the flowing air droplet by droplet. The desired quantity of oil which is to be released into the air during a specified period of time can be selected with an adjusting screw at the top of the lubricator. A sight glass is installed within the stream of air for monitoring purposes.
The pressurised oil reservoir must be exhausted in order to refill it with oil. A special valve is included in the lubricator to this end, which exhausts the lubricator automatically when it is opened (design varies from series to series).
Prevailing working pressure in the oil reservoir forces oil through the tube. Initially, the oil advances into the oil sight glass via a channel, where it passes through a restrictor at the same time which doses the oil. Drop by drop, it then advances into the venturi nozzle's suction channel, which atomises it into the compressed air.
Air flowing through the lubricator is fed through a pneumatic distributor prior to lubrication. The distributor consists of a specially shaped rubber diaphragm, whose shape has a corresponding influence on flow.
Interaction between the venturi nozzle and the distributor's shape-dependent aerodynamic drag assures lubrication which is proportional to the flow rate. Otherwise, for example, the air would be over-lubricated in the case of minimal flow rates.
Types of oil
Oil quality is broken down into ISO classes which are defined in the ISO 3448 standard. Types of oil: Festo special oil, ARAL Vitam GF 32, BP Energol HLP 32, ESSO Nuto H 32, Mobil DTE 24, Shell Tellus Oil DO 32.
cST = centistokes
The centistoke is a unit of measure for the kinematic viscosity of oil. It is specified as m²/s. Kinematic viscosity = dynamic viscosity + density.
Over-lubricated air
If silencer exhaust ports become discoloured, this may indicate that there’s too much oil in the air.
It is important to use the correct type of oil for your application, as using the wrong oil can lead to problems such as reduced efficiency or even damage to the pneumatic components. It is also important to maintain and properly fill the lubricator, as a lack of lubrication can lead to premature wear and failure of the components.
There are many different applications where a lubricator can be used in a pneumatic system. Here are some examples: