The Hidden Dangers of Topping Up Your Lube Oil

Synthetic lubricants were born out of a need for better lubricating properties, and the unavailability of crude oil in Germany. Aviation was the first application for synthetic lubricants, as they are superior to mineral oils at cold start up and cold climates. Synthetic oils have a higher Viscosity Index, offering better viscosity stability at varying temperatures. Group IV synthetic oils are man-made from PAO’s (polyalphaolefins) and Group V oils are made up of polyesters, phosphate esters, di-esters, alkylated benzenes and other synthetic molecules.

Another way of comparing the various refinement of oil is to compare the oil to a fluid with balls of varying sizes in suspension. The lower the Group level of oil, the greater variety of ball size and shapes (which represent the types of molecules). Group 1 oils will have millions of differing atomic compounds (molecules) making up the oil. As the oil is refined, the oil is more uniform and the ‘balls’ are the same size. Synthetic oils have only one size ball.
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The obvious answer is ‘No’, as there are other influencing factors that impact on equipment life such as start-up wear and vibration… but equipment life when oil is clean may surprise you.

Clean Oil Really Does Matter

When you order ‘new’ oil in to stock it typically has an ISO 4406 code of 21/18/16 NAS 10, which is very dirty for close tolerance rotating machinery.  Most OEM’s specify a cleanliness code of 16/14/12 NAS 5, which is substantially cleaner than new oil, but if you can reduce that cleanliness code to 15/12/10 NAS 4, you will extend the machinery life cycle by two and a half times.   So, if your rotating asset costs $10M with a service life of 20 years, you could expect a service life cycle of 50 years, so $10M for a 50 year service life is a prudent investment compared to $25M for the same service life.

ISO 20/18/16 NAS 10 as delivered 'new'!

ISO 15/12/10 NAS 4 - Post filtration, clean

                        

The British Hydraulics Research Association (BHRA) conducted a three year field study of a range of more than 100 rotational and hydraulic machines to ascertain equipment life and the results were compelling.
What the survey found was that breakdowns diminished and the life of equipment improved greatly the cleaner the oil was kept. Nearly 20 times longer… It proved that if you want to spend less in maintenance and downtime, simply keep your oil clean.

Case Study - Aluminium Smelter

A Queensland aluminium smelter which adopted a proactive condition monitoring program, has changed its hydraulic oil overhaul schedule from annually out to 7 years, by fitting desiccant breathers, servicing the oil with vacuum dehydration and fine filtration.  Traditionally, their gearboxes gave 10 years of service life, and now the gearboxes have a service life expectancy of 25 years.  Downtime and wear rates have been greatly reduced so they are confident about moving to a synthetic lubricant.  Synthetic lubricants do not tolerate moisture or particulate contamination as well as mineral oil but do improve your equipment life when kept clean.

There are many successful examples of this proactive condition monitoring, where operational and maintenance budgets have been greatly reduced and equipment capital budgets are halved.

Take Action with Your Lubricants 

You want to see thumbs up on your Lab reports...

There are many successful examples of this proactive condition monitoring, where operational and maintenance budgets have been greatly reduced and equipment capital budgets are halved.

Fact - Keep your in-service oil clean and dry and unscheduled downtime, failures, hot spots, wear, and breakdowns will reduce.

The Cost Benefit Analysis

As an added benefit, the expenditure for implementing proactive condition monitoring and lubrication filtration servicing is insignificant, compared to the savings in capital and operational up-time.  One unscheduled stoppage in a plant could pay for years of lubrication maintenance and service.
What are you wanting to see on your lab tests?

Summing Up

It may be naïve to suggest close tolerance machinery can last forever, but you can increase its service life cycle by multiples saving you money and maintenance headaches, all by simply keeping your lube oil clean.

So yes, your close tolerance machinery can nearly last forever, if your lube oil is well serviced.

If you would like further information on this article or others, please let me know or visit our website.

James McAllister
james@biokem.com.au
Ph 0466 625 225
www.biokem.com.au

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Has your Lubricating Oil got Gas?

Entrained gas can reduce your oil lubrication effectiveness by up to 80%

Entrained gas reduces the efficiency of your lube oil, which can have negative consequences on the machinery it is supposed to be lubricating. This can range from minor consequences up to devastating effects.  The longer it’s left, the worse the consequences.

But first, here is a description of the problem - this is about fluid aeration, it happens at high temperature and compression rates, when the lubricating oil in your equipment comes into contact with gas, bubbles form in the lube oil. When oil is aerated, it won’t give a full film, leaving sensitive components unlubricated, causing extremely premature wear rates or catastrophic failure. 

Electrophysical Separation Process

Before you open a bottle of Coke or beer there are no visible bubbles, this is dissolved gas.  When you open the bottle you see tiny bubbles in suspension - this is entrained gas.  The same as in your oil.

There are several situations when this can occur even in closed loop systems.

Return lines where oil ‘plunges’ into the tank under gravity or pressure.

Hydraulic systems under suction resistance.

When process gas comes into contact with your oil.

Sudden pressure drops.

What are the effects? Machinery operating with entrained gas in its lube oil has the same effect as oil starvation as your lube oil is just not lubricating all of the area it was designed to.  When gases in oil are compressed (eg. rolling element bearings, gear teeth and hydraulics) oil temperatures rise causing other issues and concerns.  If left unchecked, the result is increased wear in sensitive and expensive components. The lubricating oil will suffer a marked degradation in quality, enabling catalysts to deplete antioxidants and other additive packages, raising varnish potential which, in turn, can decrease tolerances and cause sticking valves (the list goes on!).  Entrained gas will also dilute the viscosity of the oil, falling outside of its design specification for the given application. Entrained gas also creates cavitation. This is caused when the pressure of the dissolved gas is higher than the fluid.  When this happens the bubbles can collapse, which degrades the quality of the oil.  It is also often the source of increased high-frequency vibrations and noise… plus it can cause direct damage to equipment. Finally, entrained gas in lube oil can reduce thermal conductivity, increase erosion, and decrease the efficiency of pumps. Your solution to restore your lubricating oil: Simple bubble removers can be effective on highly aerated systems and work like mini centrifuges to spin the gas and bubbles into the middle of the vortex and then remove them.  However, to remove 100% of entrained gas and 90% of dissolved gas you need vacuum dehydration. Vacuum dehydration or VDOPS is ideally a six stage process with the added benefit of removing moisture and dirt as well as the gas.  The oil is passed through a vacuum chamber at an elevated temperature, above 66˚C is ideal for most oils for moisture or gas removal to separate the oil from water vapour and process gas.  The resulting lube oil is almost completely free from gas and ready for service. Oil purification systems Australia Bulk Particle Removal – The first stage of the process, where large particles are removed by a 10µm or greater filtration element. (Element selection differs with viscosity). Temperature and Viscosity Adjustment- The oil is heated to above 66˚C, which lowers the viscosity for higher flow and processing rates, and allows for vacuum dehydration to occur. Vacuum Chamber - is where the heated oil is exposed to vacuum, where gas is removed, and water evaporated. Fine Filtration – Using absolute β1000 pleated microglass filtration media, particles as small as 2 micron can be removed (dirt, scale, rust, wear metal, silica, etc). Multi pass procedure - Used to maximise the results, five passes are often used to achieve the targets of 100 percent entrained gas removal, and 90 percent dissolved gas removal. Additive blending – If available, this is an optional restorative process which returns the lube oil to an as-new, or higher specification, as required. If you would like further information on this article or others, please let me know or visit our website.

ENTRAINED GAS IN LUBRICATION OIL

BioKem Oil Services has specialist equipment that will remove 100% of entrained gas from lubricating and hydraulic oil.

BioKem has the equipment and the know-how to perform on-site oil filtration, dehydration and removal of entrained gases from your lubrication oil.  Entrained gas is not just problematic from simple air bubble generation, but can also ‘dilute’ or lower the mineral oil viscosity of the oil.

Is the presence of entrained gases affecting your lubrication circuit?

If the lubricating oil comes into contact with gas at an elevated temperature and pressure then gas entrainment may occur.  ‘Entrainment’ or ‘fluid aeration’ can cause numerous problems in hydraulic and lubrication oil systems including: unacceptable noise, poor component response due to spongy behaviour of aerated fluids, cavitation damage and severe fluid degradation.  If bubbles are present in the fluid in the reservoir, they may be sucked into the pump, where the bubbles’ volume will increase, due to pressure decrease along the suction line, and then compress again when a region of higher pressure is encountered. This compression is nearly adiabatic (the bubble gets hot, but does not materially increase the temperature of the surrounding fluid), resulting in tremendous localized temperatures at the gas-liquid interface. This may cause thermal cracking and sludge/varnish formation. In compressors, various process gasses, including soluble hydrocarbons like methane, butane, propane, petro-chemical processing sour gases, etc., are soluble in mineral oils and effectively cause ‘dilution’ or a lowering of the mineral oil viscosity reducing lubricant efficacy.

Cambridge Viscosity President Robert Kasameyer says that "when the compressor is running, the lubrication oil is hot and the entrained gas remains in gaseous phase. When the compressor is down, the lubrication oil cools and some of this gas can become liquid, which causes the lube oil viscosity to drop. Then, when the equipment is re-started but before it heats up, the equipment is operating with inadequate lubrication, which can be a disaster! If it makes it through this stage, the light hydrocarbons will again become gaseous, separating out of the lube oil, and the lube oil will regain its proper viscosity. But the damage will already be done."

The key thing to know is that once oil has been absorbed into the gas flow, it will not be collected by the oil separator.

Bubble removal devices can be used to mechanically remove bubbles from fluids however this is not a 100% effective method and foaming can occur.  Removal of entrained gas with a vacuum dehydrator provides for 100% removal of entrained gases and advantages such as the possibility of smaller reservoir size and lower overall system cost. 

BioKem VDOPS achieving ISO 10/8/7

The installation of an in-service, kidney loop, BioKem Oil Services vacuum dehydrator (VDOPS) will ensure that 100% of entrained gas and 90% of dissolved gas is removed and that the oil is free from not only gas, but is very dry and clean.  Our VDOPS systems are equipped with high efficiency pleated Microglass filter elements rated Beta(c)1000 per ISO 16889 to quickly and reliably achieve very low particle counts to meet or exceed an ISO 16/14/11 cleanliness level.

BioKem VDOPS 190l/min vacuum dehydrator

SGSpost filter Lab Test of 5,000l lube oil tank showing a moisture level of 8ppm!