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Air line lubricator

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What's The Air Line Lubricator?

Air line lubricator is a device which adds controlled quantities of tool oil into a compressed air system to reduce the friction of moving components. Most air tools, cylinders, valves, air motors, and other air-driven equipment require lubrication to extend their useful life. Normally we intall it downstream of the compressor and upstream from the air tool or component. It provides a continuous stream of atomised oil to the points of the system. In this way the lubricant provides much more effective and longer-term protection of the friction surfaces. Once a lubricator is added to the line, we should use it continuously.

The Structure Of Air Lubricator

The Work Principle Of the Air Line Lubricator

Why the air line lubricator is necessary in a pneumatic system?

Types of Airline Lubricators

Main line lubricator

Medium lubricator

Small size lubricator

The micro-fog

The Applications Of Lubricators

How to Choose The Lubricator?

(1) Pressure characteristics

(2) Minimum fogging flow

(3) Oil quantity adjustment ability

(4) Oil mist particle size

(5) Minimum non-stop refueling pressure

There are other factors to consider as well.

Our Air Line Lubricator Products

The Structure Of Air Lubricator

A typical air regulator include the following components:

1. The Oil Cup⑨: We use it to keep oil which is ready for injecting into the downsteam system. Normally, we made it by the pellucid ethoxyline. But some company supply the lubricators with the aluminium cup, and assemble a sight gauge.

2. The Dip Tube⑭: It’s a short PU tube ,which is connected with the niddle valve.It’s incharge of the transmission of the lubricant from the oil cup to the spray nozzle under the needle valve.

3.The lubricator cap: We intergrate four main mechanisms in the cap.

A. The filling port: Which is for filling the oil into the oil cup.

B. The check valve⑦: under the cap which is for pressurizing the oil cup, and push the oil to get in the spray nozzle through the dip tube. The other function is to prevent the compressed air blowing into the cup when filling oil. The check valve is composed by a spring, and steel ball , and the valve seat.

C. The needle valve⑪: We use it to control the flow rate of the spray nozlle.

When the we turn down the needle valve knob, the needle piston is tend to seal the orifice of the nozzle. Therefore to reduce the oil supply. Conversly, increase the oil supply.

D. The check ball⑬: between the dip tube and the needle valve. We assemble it to shut off the air rute when filling oil into the cup.

E. The sight dome②: We can check the situation of oil injection through the sight dome.

The Work Principle Of the Air Line Lubricator

The following figure indicate the working principle of air lubricator.

1. The compressed air enters the lubricator and then enters the chamber of the cup through the small check valve⑦. Infact the check valve always intent to close due to the spring force. But the compressed air press the ball downward, so the air will leak in to the cup.

2. In the upper cavity of the oil cup, the pressure gradually rises. Thus sequentially to press the oil surface, and the oil get into the dip tube⑭ to pushes up the steel upper ball.

3. Finally oil drip flows into needle valve⑪ and then to the sight dome②, and then run over into the spray nozzle① (Oil Drip Orifice In Dome).

4. Turning the needle valve⑪ can adjust the flow rate. Normally the oil dripping amount varies from 0 to 120 drops per minute.

How To Refuel the Lubricator ?

There are two types lubricators in the market, most need to stop the air supply when refueling, and some models no need stoping the air supply.

For the second model, just need to unscrew the plug on the filling port of the oil cup, and the compressed air in the oil cup is gradually emptied. Then inject the lubricating oil into the cup directly!

The Filling Process

At the moment, the upper cavity of the oil cup is open to the atmosphere, the pressure difference between the upper and lower of the check valve make the valve closed. Due to the small amount of leakage, the compressed air basically won’t enter the oil storage cup. And the check ball upper the dip tube moves down to the bottom at this time, so as to prevent the compressed air from pouring into the oil storage cup. At this time, you can add oil to the storage cup through the oil filling port to the specified liquid level and then tighten the oil plug. After a while, the special one-way valve will enter the working state again, and the lubricator will start working again.

Why the air line lubricator is necessary in a pneumatic system?

Add Moderate Lubricant

The use of an air line lubricator solves the problems of adding too much or too little lubrication that arised with conventional lubrication methods such as a grease gun or oil. Airline lubricators also supply the right kind of lubricant for the tools used.
Once the we adjust the lubricator, an accurately metered quantity of lubricant will flow into the air-operated equipment. The only maintenance required is a periodic refill of the lubricator reservoir.

Wash Away The Compressor Oil

Adding lubrication to a system also “washes away” compressor oils that travel through the system in air tank. Mineral oils added to the system prevent synthetic compressor oil build-up in system components. When there is no lubricators in a system, a additional coalescing filter is indispensable to remove compressor oil aerosols.
Downstream flow requirements determine the size of lubricators. Therefore, an analysis of air flow rate is essential. After clarified the air consumption rate, to choose a suitable lubricator is a easy work!

Types of Airline Lubricators

Lubricator generates a mist of around 2-100 microns; all of the oil drops seen in the site dome pass into the air stream.

There are three types oil-fog lubricator:

Main line lubricator: used in the main line, normally installed behind the air compressor.

Medium lubricator: Normally we install it on the single machinery.

Small size lubricator: We assemble it with upstream air tools.
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 G1/8 to G3/4 as standard, with an NPT option.

The Applications Of Lubricators

Main line lubricator: By definition, the droplets in the oil-fog lubricator are bigger, thus, heavier. This is ideal model where heavier lubrication is necessary. For example with slow moving, large bore cylinders; air motors and in front of the mainline application. One benefit for this type of lubricator is it does allow to fill the oil reservoir whilst the system is running.

Medium lubricator : Conversely, the mist from the lubricator is moderate and these are suitable for complex systems. Such as 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.

Small size lubricator: It 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 it’s much better suited to these applications having a much shorter time to operation.

The micro-fog: With the extremely light weight and small volumn, it’s perfectly suitable for the small air tools! So most time we assemble it on the air tools directly with only increase negligible wieght!

How to Choose The Lubricator

(1) Pressure characteristics

We express the characteristics of the oil mist by the pressure drop characteristics. That is, the relationship curve between the output and inlet pressure drop under the condition of a certain input pressure. The pressure drop of the common lubricator is not more than 0.015MPa.

(2) Minimum fogging flow

The oil droplets atomizing only happen after the air flow through the lubricator reaches a constant value. Usually, when the oil in the normal working level, under the certain working pressure, the minimum air flow rate for misting the oil droplets is called the minimum misting flow rate.

(3) Oil quantity adjustment ability

Under the specified pressure and flow, adjust the oil volume throttle valve, and its output dripping oil volume should be continuous and uniform.

(4) Oil mist particle size

The oil mist particle size refers to the diameter of the oil mist particles produced by the lubricator. The oil mist particle size of the ordinary type lubricator is 20um, and the micro-mist oil mist particle size is less than 2μm.

(5) Minimum non-stop refueling pressure

Refers to the minimum pressure (generally not lower than 0.1MPa) of the lubricating . When the input pressure is lower than the minimum non-stop refueling pressure, the check valve in the lubricator cannot overcome the elastic force and close the air intake channel of the oil cup, and cannot achieve non-stop refueling.

There are other factors to consider as well.

Who will be responsible for keeping the lubricator bowl full of oil?
Is there any one to train them to adjust it to provide the right amount of oil?
Is there any one to train them to only use the proper oil?
These are important considerations. Many machines have had performance issues directly related to poor lubricator maintenance and adjustment. If the lubricator runs out of oil, the oil inside the system will tend to dry out, causing many pneumatic products to stick or slow down. Be sure the worker inject proper oil. As improper oil may damage the entire pneumatic system. Don’t apply too much oil, as it tends to come out of the system. It may xhaust where it can create puddles of slippery oil or oil vapor in the atmosphere.

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