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Oil Mist

Overview

Oil mist origin was as consequence of achieve a properly lubrication in high speed fitting bearing, where grease lubrication produced exceed heating, and oil circulation systems had problems due to high costs and, moreover, loss problems due to detent tightness.

Consequently, it was developed a system for transporting small oil quantities through the air. The first oil mist systems with classic Venturi and high-pressure air had as main inconvenience a great air consumption and the transport of oil particles excessively thick, resulting in condensation in pipe walls. On the other hand it was only possible to lubricate limited lube points with very low viscosity oils.

• Advantages
• System basis
• Components
• Lubricant choice
• Products

Advantages

RIVI, after several years of experience manufacturing Oil Mist equipment, has developed complete lubrication systems, with advantages as follow:

1. Lubrication of bearings (roller, main, taper, bush-type, ball, plain, collar, …), guides, supports, gears, chain, etc,… by means of a single installation.
2. No distance limit. (70 m)
3. Possibility to atomize high-viscosity oils (up to 60ºE with 50ºC).
4. Minimum compressed air consumption
5. Minimum oil consumption, being supplied continuously by means of an automatic & centralized lubrication system
6. Certainty to lubricate by means with new and clean oil (it is impossible to transport impurities in oil particles, as they are atomized minor 2 micron)
7. Refrigeration & lubrication at the same time
8. Generation of small pressure inside the bearing, ensuring no external hazardous impurities can get into the bearing.
9. Absence of failures or breakdowns, as the equipment does not have any mobile device and consequently does not require any maintenance.
10. - Complete set of visual & electrical monitoring devices available
11. Less total cost than conventional centralized lubrication systems (even less than using non-automatic pumps).

Main basis

It is a centralized lubrication system where a compressed gas (air generally) is used to atomize oil, becoming Oil Mist; then it is given through a low-pressure system to different application lube points.

The oil is atomized by airflow through Venturi nozzle. The deflector causes the decantation of heavy oil particles returning into reservoir. The resulting air-oil mixture is the Oil Mist. The Oil Mist has oil particles with medium diameter of 1-2 microns. These particles are driven to bearings through distribution pipes with speed of 7.5 m/s

The oil particles come to the lubrication points with enough speed for producing the condensation in the surface. The Oil mist can be introduced in closed places if the surfaces to be lubricated spin to enough speed. The speed of gears, chains and others rotative devices will cause the condensation able to guarantee a correct lubrication. The fittings must be designed for condensation function. With an adequate pressure drop through the fitting it is generated an Oil Mist speed (upper to 30 m/s) and resulting in turbulence flow. If the length fitting is much more large than the diameter fitting (with a minimum length of 6 times the diameter for a pressure drop approximately of 200 mm of H2O) will obtain a turbulence area enough to reach a right condensation. The deflectors in the fittings increase the condensation; therefore almost every oil atomized particles become into oil drops.

Total amount of Oil Mist depends on the generator. This amount is related to Venturi nozzle (nominal diameter) and air pressure applied. The application fittings deal the distribution of the Oil Mist generator.

The pressure inside the system must be equal to drop pressure required in the application fittings in order to deliver - from generator to every lube points - the total amount of oil mist required.

Oil Mist systems are designed to maintain an operating pressure inside the line between 125 - 1000 mm H2O. The operating pressure is chosen for each application depending on the fittings, oil viscosity and surface roughness.

Oil Mist lubrication system provide with unique advantages. Continuous application of oil is exactly what friction areas require. Oil Mist system ensures a non-stopping lubrication, and avoids to install an oil circulation application. Therefore, it results much more economical for a lot of projects an solves the problem about packing´s overall life time.

Air used to distribute the lubricant, enables extra-advantages, specially wherever lubrication by means of grease was considered the most suitable (until now). Oil Mist keeps the support under a light positive pressure, and the air flow prevents external polluting particles from entering.

Due to there are not cycling devices, movement parts, and it woks with low pressure, Oil Mist is a centralized lubrication system of total reliability. It can include electrical monitoring to control the operation of the oil mist system.

Components

The main components are:

1. A filter separator in air line for ensuring clean air distribution
2. A air FRL group for controlling the air flow to generator.
3. Generator provided of Venturi nozzle, regulator screw, aspiration pipe and reservoir with visual level control.
4. Pipes for mist distribution in order to connect to application fittings.
5. Application fittings for condensation.

The system accessories:

1. Solenoid valves to close and open the air flow to generator.
2. An oil heater in the reservoir in order to control the oil viscosity
3. An air heater in order to control the air temperature inspite of ambient temperature variations.
4. A switch for monitoring of minimum level and automatic reservoir filling.
5. A pressure switch for controlling the operating - high or low - pressure.
6. A pressure gauge for visual control of the operating pressure.

Lubricant Choice

Type of Oil:

• For applications that EP oils are not required. Use mineral oils for turbine and for all industrial applications. Use motor oils for applications in vehicles.
• For applications that EP oils are required. It is better to use adequate oils for Oil Mist applications. It is also adequate oils for industrial gears of vehicles.
  

Oil Viscosity:

• In most of applications with normal temperatures, are used oils of 500 to 700 SSU 100ºF (14.5 – 20 ºE at 38ºC).
• For cold conditions and high speed ball bearings, oils of 50 to 300 SSU with 100 ºF (1.6 – 8.6 ºE at 38ºC)
• For hard working applications oils of 700 – 1000 SSU with 100 ºF (20 - 28.8 ºE at 38 ºC)
• For great hard working devices, oils of 1500 to 2350 SSU with 100 ºF (42.7 – 65 ºE at 38ºC)
• For big gears, low speed, semi-closed, oil of 3000 to 6000 SSU with 100ºF (78 – 170 ºE at 38 ºC)
  

In Oil mist installations oils with common additives can be used with the following exceptions:

1. Oils with solid particles suspended like graphite, etc…should not be used without manufacturer approval
2. No-misted fluids ,specially silicone, in 5/million rates
3. Additives for old motors and others similar components.
4. Oils with EP agents should be used with caution in order to avoid chemical reactions that could start in applications with Thermo-air heaters or with generators which do not have the heater element inside the reservoir.
5. Oils made from lactic and soap basis.
6. It is possible to use additives detergent or materials that increase the oil viscosity which do not have EP; in this way the excess of mist is reduced. They can also remove the residues of the supports in the highest temperature applications. The rate oil/air is reduced depending on these additives. Some of these additives can reduce excessively the expenditure of the oil, as well as sensible increases of condensation in the pipes, therefore these kind of applications require special attention.
   

Products

	Oil Mist generator box		(22 Kb)
	Oil mist Equipment		(34 Kb)
	Oil Mist Station Closed		(21 Kb)
	Oil Mist Station Opened		(28 Kb)