AEMT - Association of Electrical and Mechanical Trades

25 July 2018
Those unwanted build-ups in Engineering Lubricants
As the Wizard of Oz’s Tin Man would tell you, moving parts are lifeless without the revitalising flow of lubricants, engineering fluids and coolants running across their surfaces.
Those unwanted build-ups in Engineering Lubricants
Oils and greases are an essential component for any machine, gearbox, transformer, or hydraulic system, and checking them not only ensures the strength of the machine, but the efficiency, safety and low running costs. 

Poor or sporadic monitoring can lead to metal or water contamination weakening the effectiveness of the coolant or lubricant. In some cases, machinery failure can be catastrophic. In the automotive and rail sectors, engine wear or lubricant degradation can create unnecessary risk to passenger safety. The industry, therefore, has been conducting chemical and physical analysis for over 40 years and the approach has been key to extending equipment life and safeguarding today’s modern rail infrastructure.

Mechanical Oil

Depending on the type of mechanical oil or grease, a complete test will look at both the lubricating physical properties of the oil and then any subsequent wear or contamination within the asset. 

Levels of silicon, iron, copper and zinc can indicate that there is wear on the bearing or gears, while viscosity, oxidation and acid levels suggest the oil is aged. Dirt ingress (grit or brake dust, for example) indicates the seals are no longer suitable, and will cause further deterioration of the equipment.  

Electrical Oil

For electrical oils, frequent analysis can help determine how well the oil is performing as an insulator, and how well the transformer is operating. Fault diagnosis is important in keeping the asset running, with oil analysis forming a large part of the diagnostics. Typically, the minimum tests for insulating oils are to test its physical properties and detect any dissolved gases within the substance. 

To determine the physical properties of the oil, a number of tests can be performed:

  • High moisture content can be detected using the Karl Fisher titration method. If water is found to be present within the oil samples, it can have critical effects on the aging rate of lubrication oils as well as direct damage to machinery.
  • Acidity within oil occurs as and when it comes into contact with air. Following oxidation, increased acidity can cause a decrease in resistivity and causes a sludge to form. By using the titration method to monitor the substances colour, an indication of the acidity levels can be formed. 
  • Electrical strength test kits can determine di-electric breakdown of the insulation properties, where a low di-electric strength indicates low conductivity. 
  • The above tests are important indicators of oil age, physical condition and insulating properties, but they are not fully inclusive. 

Gas build-up:

A build-up of dissolved gas within the oil can also cause transformers and electrical assets to break down. Testing the rate at which the gas builds-up and understanding the distribution of these gases provides crucial information on the type of electrical fault, as well as the severity of it. By investigating the concentrations and ratios of rogue gases, a dissolved gas analysis can spot the potential for high energy arcs and sparks.

Gases looked out for include: Methane (CH4), Ethane (C2H6), Ethylene (C2H4), Acetylene (C2H2) and Propane (C3H8); as well as atmospheric gases: Oxygen (O), Hydrogen (H), Nitrogen (N), Helium (He), Carbon Monoxide (CO) and Carbon Dioxide (CO2).

Summary:

In summary, if you’ve any sympathy with the Tin Man, then you’ll remember that monitoring both the physical and gaseous properties of oil is essential in prolonging the life of the asset and its long-term care and use. 

Detecting the ‘unseen’ issues in advance can prevent damage and failure to electrical and mechanical equipment, thus reducing costly repairs and production downtime.

Using sample collection kits, trends and patterns can be identified through an online asset management portal. Done regularly, informed decisions can then be made to maintain the quality of the equipment’s oil.  

SOCOTEC’s highly experienced team have a dedicated UKAS accredited lubricant and fluid analysis laboratory in Hexthorpe, South Yorkshire. They provide full scrutiny for your mechanical and electrical oils, fuels and greases.

SOCOTEC’s condition monitoring services include:
  • Chemical, physical and microbiological analysis of lubricants and fuel.
  • For transformer oils, we check water content, electric strength, contaminants, and acidity. 
We also provide:
  • bespoke sample collection kits
  • analysis of lubricants for wear
  • additive and contaminant elements within engines
  • gearbox and hydraulic oils
  • expert interpretation of results and trend predictions

Media

(Infrastructure & Energy) 4 Hexthorpe Road, Doncaster, DN4 0AE, England
01302 380152
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