1. Scope and Purpose
This practical guide details procedures for maintaining oil mist lubrication systems. It covers fog generator service, close inspection of connections and distribution lines, and functional verification of drain systems. Correct application of these procedures is crucial to ensuring consistent and accurate delivery of lubricant to application points such as bearings, gears, housings and other mechanical components in industrial manufacturing environments. This maintenance must be carried out preventively, according to the scheduled maintenance plan, or when operational anomalies are detected, as well as after any repair to components that depend on this lubrication system. The main objective is to prevent premature component failures, optimize equipment operational efficiency and extend its useful life.
2. Safety Precautions
ATTENTION: Safety is essential. Before beginning any maintenance procedure, strictly follow applicable safety guidelines.Lockout/Tagout (LOTO): It is mandatory to de-energize and lock out all energy sources (electrical, pneumatic) of the system and associated equipment. Confirm that the compressed air and lubricating oil system has completely depressurized before opening any connections.
Personal Protective Equipment (PPE): Always use safety glasses with side protection (ABNT NBR 16672), nitrile or oil-resistant PVC gloves (ABNT NBR ISO 374-1), safety shoes with steel toe caps (ABNT NBR ISO 20345) and hearing protection (ABNT NBR 16072) in noisy environments.
Dangerous Energies: Be aware of compressed air under pressure, lubricating oil that may be pressurized and/or heated, and moving parts of equipment.
Waste Handling: Collect and properly dispose of all used lubricating oil and contaminated materials in accordance with local environmental regulations.
3. Tools and Materials Required
To carry out this maintenance, have the following tools and materials available:
| Tool/Material | Specification | Quantity |
|---|---|---|
| Combination Keys | Opening from 6mm to 32mm | 1 set |
| Screwdrivers / Phillips | Various sizes | 1 set |
| Pliers | Universal, Nozzle, Cut | 1 of each |
| Torque meter | Range from 5 to 50 Nm, accuracy +/- 4% (ABNT NBR ISO 6789) | 1 unit |
| Calibrated Manometer | Range from 0 to 10 bar, accuracy class 1.0 (ABNT NBR 14105) | 1 unit |
| Compressed Air Gun | With safety nozzle | 1 unit |
| Cleaning Kit | Soft bristle brushes, flexible shafts | 1 set |
| Plastic Spatulas | For removing joints without damaging surfaces | 2 units |
| Lubricating Oil | According to OEM specification (e.g. ISO VG 32, 46 or 68) | Required volume + 10% |
| Mist Generator Filters | Air filter element (5 microns), oil coalescing element (1 microns) | 1 of each per generator |
| Seals and Gaskets | O-rings, gaskets (oil compatible material) | As needed |
| Connectors and Nipples | Reserves for emergency replacement | 2 of each type |
| Degreasing Solvent | Non-flammable, safe for rubbers and plastics | 1 liter |
| Cleaning Cloths | Clean and lint-free | 1 package |
| Containers for Used Oil | With lid, suitable capacity | 20 liters |
4. Pre-Maintenance Inspection Checklist
Before starting maintenance procedures, perform this inspection to identify anomalies:
| Item | Verification | Acceptance/Rejection Criteria | Observations |
|---|---|---|---|
| Oil Level | Check level in the fog generator reservoir | Within the minimum and maximum range indicated on the display | Low level indicates leakage or excessive consumption; high level indicates poor return. |
| Air Pressure | Monitor atomization air pressure on the generator pressure gauge | According to OEM specification (e.g. 3.5 to 4.5 bar) | Pressure outside the range affects fog formation and distribution. |
| Oil Temperature | Check oil temperature (if the system has heating) | According to OEM specification (e.g. 40 to 50 °C) | Incorrect temperature alters viscosity and atomization capacity. |
| Leaks | Visual inspection of all lines, connections and nozzles | No leaks or oil exudation | Leaks indicate loose connections, damaged seals or cracked lines. |
| Noise/Vibration | Listen to and touch the fog generator and its surroundings | Absence of abnormal noises or vibrations | Noises may indicate internal problems with the generator or oil pump. |
| Alarms/Indicators | Test or check the status of low pressure, low oil level alarms | Alarms and indicators working properly | Failed alarms can hide critical problems. |
| Mist Quality | Observe the mist at the application points (if possible) | Fine, uniform and continuous mist | Patchy or thick mist indicates nozzle or pressure problems. |
5. Step by Step Procedure
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Preparation and Security
Action: Make sure the oil mist lubrication system and the equipment it serves are isolated. Apply the Lockout/Tagout (LOTO) procedure to all energy sources, in accordance with NR-10 and NR-12.
- Values: Check with a calibrated pressure gauge that the pressure in the compressed air system and oil lines is at 0 bar before proceeding.
- Visual: All electrical breakers deactivated, compressed air valves closed and locked.
- Common error: Starting work without confirming complete depressurization of the system, which can cause serious injuries due to air jets or pressurized oil.
-
Mist Generator Service
Action: Drain the oil from the fog generator reservoir into an appropriate container. Then, dismantle the air and oil filter housing.
- Values: Dispose of used oil in an environmentally friendly way.
- Visual: Observe the presence of sediment or contamination in the drained oil.
- Common mistake: Disposing of used oil inappropriately, violating environmental standards.
Action: Replace the air and oil filter elements with new ones, according to the manufacturer's specifications (e.g.: 5 micron air element, 1 micron oil coalescing element).
- Values: When reassembling the filter housings, apply a torque of 20-25 Nm (according to ABNT NBR ISO 6789 for threaded elements) on the unions, ensuring adequate sealing without damaging the components.
- Visual: New filters installed correctly, with no misalignment or damage to seals.
- Common error: Reusing saturated filters or installing filters with incorrect specifications, compromising air and oil quality and, consequently, the formation of mist.
Action: Refill the reservoir with new lubricating oil of the correct OEM specification. Adjust the atomization air pressure.
- Values: Refuel up to the maximum level indicated. Turn on the compressor and adjust the pressure to 3.8 bar, using a calibrated pressure gauge, as specified in the equipment manual and compatible with NBR 13809 for pneumatic systems.
- Visual: Manometer stable at the desired pressure. Visible oil level in operating range.
- Common mistake: Adjusting pressure without a calibrated pressure gauge or outside the recommended range, resulting in inconsistent mist or insufficient oil flow.
Inspection and Maintenance of Connections
Action: Visually inspect all distribution lines, connections and spray nozzles. Look for signs of leaks, mechanical damage (dents, kinks) or corrosion.
- Values: In dosing nozzles, check the diameter of the holes. The manufacturing tolerance is generally +/- 0.05mm of the nominal value (e.g. 0.5mm nozzle should be between 0.45mm and 0.55mm).
- Visual: The lines must be intact, without folds that could restrict the flow. Connections must be dry and tight.
- Common error: Ignoring micro leaks, which can lead to loss of pressure in the system, reduced lubrication efficiency and contamination of the work environment.
Action: Clean or replace spray nozzles that are clogged or worn. If cleaning is feasible, use low pressure compressed air.
- Values: The compressed air pressure for cleaning small nozzles should not exceed 2 bar to avoid damage. Use flexible nylon swabs to remove residue if necessary.
- Visual: The nozzles must provide a uniform and fine flow of mist.
- Common mistake: Using metal tools to unclog nozzles, permanently damaging their internal tolerances and altering the spray pattern.
Action: Tighten loose connections using the torque wrench.
- Values: For 1/4" NPT connections, apply 15-18 Nm torque. For 1/2" NPT connections, apply 30-35 Nm. Consult the manufacturer's manual for specific values.
- Visual: Firm connections, without visible gaps.
- Common error: Over-tightening connections, which can cause thread deformation, broken lines or damage to seals, resulting in new leaks.
-
Checking the Oil Drains
Action: Inspect and clean all drain lines and check valves. Remove any build-up of solidified oil, debris or sludge.
- Values: If possible, measure the drain flow. A minimum flow of 0.5 L/min per largest diameter drain is an indication of unclogging, but this value can vary significantly depending on the system design.
- Visual: Drain lines must be completely free of obstructions, allowing the free flow of condensed oil.
- Common error: Partially blocked drains cause oil buildup in bearing housings, leading to overheating, oil degradation and premature failure of lubricated components.
Action: Test the operation of the check valves in the drain lines.
- Visual: The valve must close completely when pressure is removed and open freely when oil returns.
- Common error: Defective check valves can allow contaminants to return to the main lubrication system or cause blockages.
6. Post-Maintenance Verification Checklist
After maintenance procedures are completed, perform the following tests to ensure system functionality:
| Test | Expected Result | Real | Approval/Disapproval |
|---|---|---|---|
| Reservoir Oil Level | Oil level in operating range | ||
| System Pressurization | Pressurized system at nominal pressure (e.g. 3.8 bar) | ||
| Leak Check | Total absence of leaks in all connections and lines | ||
| Mist Pressure Monitoring | Stable fog pressure in the generator and at the application points | ||
| Generator Noise/Vibration | Absence of abnormal noises or vibrations in the generator | ||
| Component Temperature | Bearing/housing temperature within operating range | ||
| Drain Operation | Condensed oil flowing freely through drains |
7. Troubleshooting Guide
Consult this table to diagnose and fix common problems with oil mist lubrication systems:
| Symptom | Probable Cause | Corrective Action |
|---|---|---|
| Insufficient or absent mist at application points | Low atomizing air pressure | Adjust air pressure regulator to 3.8 bar. Check compressed air supply. |
| Dirty/clogged air or oil filter | Replace air and/or oil filter element. | |
| Clogged or damaged spray nozzles | Clean or replace spray nozzles. Check the diameter of the holes. | |
| Leaks in distribution lines or connections | Visually inspect, tighten loose connections with torque wrench (15-35 Nm), replace damaged lines/seals. | |
| Excessive mist or high oil consumption | Too high atomizing air pressure | Adjust air pressure regulator to nominal value (3.8 bar). |
| Spray nozzles with very large holes | Replace nozzles with others with the correct nominal flow. | |
| Blocked or inoperative drains | Clean drains and check the operation of check valves. | |
| Oil contamination in the reservoir | Damaged reservoir or generator seals | Inspect and replace compromised seals. |
| Poor compressed air quality | Check and maintain the air treatment unit (filters, dryers) that feeds the system. | |
| Return of contaminants through drains | Check check valves on drains and ensure adequate drainage. | |
| Low oil temperature (in heated systems) | Heating element or thermostat failure | Check and replace defective heating element or thermostat. |
8. Recommended Maintenance Plan
An effective maintenance schedule ensures system longevity and performance:
| Task | Frequency | Estimated Duration | Skill Level |
|---|---|---|---|
| Checking the oil level | Daily | 5 min | Operator/Technician |
| Visual inspection of leaks and noise | Daily | 10 min | Operator/Technician |
| Mist Pressure Check | Weekly | 15 min | Technician |
| Cleaning/Replacing the air filter (pre-filter) | Monthly | 30 min | Technician |
| Inspection/Cleaning of drains | Monthly | 1 hour | Technician |
| Replacing filter elements (air and oil) | Quarterly or according to manufacturer specification | 2 hours | Technician |
| Detailed inspection of nozzles and connections | Semiannual | 4 hours | Specialist Technician |
| Lubricating oil analysis | Annual | (External) | Specialist Technician |
| Calibration of instruments (manometers, thermostats) | Annual | 2 hours | Specialist Technician |
9. Spare Parts Reference
Efficient maintenance requires access to quality replacement parts. UNITEC-D offers a wide range of components. See the table below for typical parts and visit our e-catalog for your order:
| Part Description | Typical Specification | UNITEC Category |
|---|---|---|
| Air Filter Element | 5 microns, coalescing | Filters |
| Oil Filter Element | 1 micron, coalescing | Filters |
| Mist Spray Nozzle | 0.5mm hole, nickel-plated bronze | Nozzles |
| Oil Distribution Hose | PTFE, diameter 6 mm, working pressure 10 bar | Tubes and Hoses |
| Straight Connector | 1/4" NPT x 6 mm, stainless steel | Connectors |
| Check Valve | Light spring, brass body, NBR seal, 1/4" BSP | Valves |
| Manometer | 0-10 bar, diameter 63 mm, radial connection 1/4" NPT | Gauges |
| Oil Level Display | Tempered glass, 1/2" BSP thread | Indicators |
| Air Pressure Regulator | 1/2" BSP, with filter, range 0-10 bar | Regulators |
Visit the UNITEC-D e-catalog for your order: https://www.unitecd.com/e-catalog/
10. References
- ABNT NBR ISO 374-1: Protective gloves against chemicals and microorganisms.
- ABNT NBR ISO 6789: Assembly tools for screws and nuts – Manual torque tools.
- ABNT NBR 13809: Compressors – Safety.
- ABNT NBR 14105: Pressure gauges – Performance requirements, selection and installation.
- ABNT NBR 16072: Hearing protectors – Requirements and test methods.
- ABNT NBR 16672: Eye and facial protection – Requirements.
- NR-10: Safety in Electrical Installations and Services.
- NR-12: Workplace Safety in Machines and Equipment.
- NBR ISO 4406: Power hydraulic fluids — Particle counting and contamination level coding.
- Specific oil mist lubrication system Original Manufacturer (OEM) manuals.
