lubricants Archives - Page 4 of 6 - Strategic Reliability Solutions Ltd

Flender Specs

Q: Why should I use a Flender spec oil?

A lot of users ask about the need to use a Flender approved lubricant for their equipment! For a gear oil to be Flender approved¹ in one of its units, the oil must be of CLP* quality according to DIN 51517-3 and motor oils must meet and ACEA Classification E2, API CF/SF. Additionally, it must meet the minimum requirements as per their specified “Proofs of performance / minimum requirements table” where the lubricants are tested at approved laboratories.

*CLP (according to DIN 51517-3)² refers to an oil that contains additives which protect from corrosion, oxidation and wear in the mixed friction zone.

The manufacturer must also guarantee performance of the lubricant both for new oil and used oil up to a permissible range as per the following:

Mineral oils (API I & II and ester oils) shall be 10,000 operating hours (2 years max)
Mineral (API III) and Synthetic (PAO & PAG) oils shall operate for 20,000 operating hours (4 years max)
All oil must produce the minimum requirements with an average operating temperature of 80°C

The following are a list of tests required by Flender which must produce specified minimum results:

FZG Scuffing test in accordance with DIN ISO 14635-1 (A/8.3/90)
FE8 rolling bearing test in accordance with DIN 51819-3 (D-7, 5/80-80)
FVA micropitting test FV A 54 VII
Flender oil Foam test in accordance with ISO 12152
Compatibility with internal coating
Compatibility with outer coating
Filterability test FFT 7300 Rev.3
Compatibility with liquid sealing component

Flender specifies the viscosity in the series to be tested for the minimum requirements.¹

The Flender approval process ensures that the lubricant being used has been tested and can withstand some degree of micropitting, scuffing, foaming and is compatible with the surfaces in which it comes into contact. Thus, this makes the Flender approved lubricant more desirable for systems which place emphasis on the compatibility of all materials in the equipment (such as elastomers, paints etc). In conclusion, if you do have a Flender gearbox or equipment, it would be wise to use the Flender approved lubricant as they have gone the extra mile to ensure that the lubricant can protect your equipment.

Users can access a listing of approved Flender lubricants here: https://www.flender.com/en/lubricants

References:

Specification for the gear oil approval for FLENDER Gear units (AS 7300) link
Trends in Industrial Gear Oils by Jean Van Rensselar (STLE, Tribology & Lubrication Technology Magazine February, 2013) link

Industrial / Strategic Tips

EALs?

Q: What makes a lubricant Environmentally Friendly?

There are many definitions of environmentally friendly. For instance, a lubricant can be environmentally friendly if it doesn’t pollute the environment which can either be understood as low toxicity or a reduced number of times that the oil is disposed.

However, there are three main factors which are considered when deeming a lubricant environmentally friendly²;

Speed at which the lubricant biodegrades if introduced into nature
Toxicity characteristics that may affect bacteria or aquatic life
Bioaccumulation potential

Biodegradability

Biodegradability is defined as the measure of the breakdown of a chemical or chemical mixture by micro-organisms. It is considered at two levels namely;

Primary biodegradation - loss of one or more active groups renders the molecule inactive with respect to a particular function
Ultimate degradation – complete breakdown to carbon dioxide, water and mineral salts (known as mineralisation)³

Biodegradability is also defined by two other operational characteristics known as:

Ready Biodegradability – occurs where the compound must achieve a pass level on one of the five named tests either, OECD, Strum, AFNOR, MITI or Closed Bottle³
Inherent Biodegradability – occurs when the compound shows evidence in any biodegradability test.³

Toxicity

The toxicity of a lubricant is measured by the concentration of the test material required to kill 50% of the aquatic specimens after 96 hours of exposure (also called the LC₅₀)¹

Bioaccumulation

The term bioaccumulation refers to the build-up of chemicals within the tissues of an organism over time. Compounds can accumulate to such levels that they lead to adverse biological effects on the organism. Bioaccumulation is directly related to water solubility in that the accumulations can be easily soluble in water and not move into the fatty tissues where they become lodged.

Common Base Oils

There are three of the most common base oils that are Environmentally Acceptable²:

Vegetable Oils
Synthetic Esters
Polyalkylene Glycols (PAGs)

These all have low toxicities and when blended with additives or thickeners for the finished lubricant, they should be retested to ensure that the additives / thickeners have not compromised the environmentally acceptable limits.

Labelling

Some lubricants can carry the “German Blue Angel Label” if all major components meet OECD ready biodegradability criteria and all minor components are inherently biodegradable.

Based on the requirements by Marpol, the International Maritime Organization (IMO) and current legislation from the European Inventory of Existing Commercial Chemical Substances (EINECS), a product may be considered acceptable if it meets the following requirements:

Aquatic toxicity >1000ppm (50% min survival of rainbow trout)
Ready biodegradability > 60% conversion of test material carbon to CO₂ in 28 days, using unacclimated inoculum in the shake flask or ASTM D5846 test¹.

References:

Lubrication Fundamentals Second Edition, Revised and Expanded. D.M. Pirro (Exxon Mobil Corporation Fairfax, Virginia), A.A. Wessol (Lubricant Consultant Manassas, Virginia). 2001.
United States Environmental Protection Agency Office of Wastewater Management Washington, DC 20460. Environmentally Acceptable Lubricants. https://www3.epa.gov/npdes/pubs/vgp_environmentally_acceptable_lubricants.pdf
Chemistry and Technology of Lubricants 3^rd Edition, Chapter 1, R.M. Mortier, M.F. Fox, S.T. Orszulik)

Industrial / Strategic Tips

Base Oil Groups

Q: How many Groups of Base oils are there?

There are 5 groups of base oils as defined by the American Petroleum Institute (API). However, between 2003-2010, the Association Technique de L’Industrie Européenne des Lubrifiants (ATIEL) (Europe) included Group VI - All polyinternalolefins (PiO).

Groups I-III are typically mineral oils while Groups IV-V are synthetic oils.

Group I: Solvent refined
Group II: Hydrocracked / Hydrotreated
Group III: Hydrocracked / Hydro-isomerized
Group IV: PAO Synthetics
Group V: All other Synthetics

Here is a table that shows the different groups.

Reference: Lubrication Fundamentals Second Edition, Revised and Expanded. D.M. Pirro, A.A. Wessol, Chapter 2.

Group I: <90% Saturates, ≥0.03% Sulphur, Viscosity Index: 80 to 120

These were characteristically the most popular initially since they were relatively inexpensive to produce (solvent refined) and used in non-severe, non-critical applications. This Group has more double bonds (carbon) which allows for an increase in stability of the carbon chain.

Group II: ≥90% Saturates, ≤0.03% Sulphur, Viscosity Index: 80 to 120

These are hydrocracked and higher refined. However, due to hydrocracking, the double bonds are reduced greatly which decreases the stability of the carbon chain. (A lot of turbine users would have noticed this change around 2010 when most Group I base oils were replaced by Group II base stock. These users saw increased varnish as the oils did not have the level of solubility that they did before!).

Group II+: (yes, this exists!) These have VIs of 110-120 with improved low temperature and volatility Characteristics.

Group III: ≥90% Saturates, ≤0.03% Sulphur, Viscosity Index ≥ 120

There is an argument that this group should be placed in the synthetic category. However, by definition, this group is the severely hydrocracked and highly refined crude oil which can be used in semi-synthetic applications as it has similar properties to that of synthetic oil. These are also called synthesized hydrocarbons.

Group III+: These have VIs approaching (or in some cases exceeding) those of synthetic PAOs (some even go above 140). They are also very pure with almost non-existent levels of sulphur, nitrogen, aromatics and olefins. Typically, Gas to liquid base oils can be found in this group as it approaches the Group IV categorization.

Group IV: Polyalphaolefins – these are very stable, uniformed molecular chains where there is a reduction in the coefficient of friction. Most are formed through oilgomerisation.

Group V: Ester and other base stocks not included in Groups I-IV such as silicone, phosphate esters, PAGs, Polyol esters, Biolubes and Naphthenics.

References:

Chemistry and Technology of Lubricants 3^rd Edition, Chapter 1, R.M. Mortier, M.F. Fox, S.T. Orszulik)
Lubrication Fundamentals Second Edition, Revised and Expanded. D.M. Pirro (Exxon Mobil Corporation Fairfax, Virginia), A.A. Wessol (Lubricant Consultant Manassas, Virginia). 2001.

Industrial / Strategic Tips

PAOs vs PAGs

Q: What’s the main difference between PAOs & PAGs?

Let’s start off with definitions!

PAO: Polyalphaolefin

PAG: Polyalklene Glycol

While both are synthetic oils they are classified under different Groups of Base oils. PAOs have their own Base oil Group IV while PAGs fall into the Group V (catch all).

PAOs

PAOs are actually hydrogenated oligomers of an α-olefin and there are different methods of oligomerisation. Due to this process, PAOs have very good low temperature properties and the products are wax free! Additionally, their lower volatilities also allow them to operate over a wide temperature range. Usually, they can be used in a lot of versatile applications such as gearboxes, screw compressors, fans, motors and even automotive!

However, PAOs have a low polarity which gives rise to poor solvency of polar compounds and issues with seal performance.¹

PAGs

On the other hand, PAGs can differ depending on their structure. For instance, Ethylene is water soluble while Propylene is not, however, neither are oil soluble. Both experience significant chemical reactions producing sludge like deposits when mixed with mineral oil.

Usually, their properties include a wide viscosity range, low pour points, good lubricity, low toxicity and non-flammable in aqueous solutions. PAGs are typically always found in fire-resistant hydraulic fluids as well as industrial gear oils, compressor lubricants, heat transfer liquids and metalworking fluids.¹

Compatibility

Both products need to be tested for compatibility with mineral oils before any mixing occurs. Additionally, most lubricant suppliers deem PAOs & PAGS as “filled for life” solutions which last for a longer time compared to mineral oils. Typically, the purchase of these products are more expensive than mineral oils, however if one looks at the cost of waste disposal and reduced downtime (due to decreased shutdowns for oil changes) the overall cost of the lubricant is by far less than that of mineral oil.

References:

Chemistry and Technology of Lubricants 3^rd Edition, Chapter 2, R.M. Mortier, M.F. Fox, S.T. Orszulik

Storage and Handling / Strategic Tips

Expired grease?

Are there any signs that my grease has expired?

There are a lot of signs to tell if grease has expired!

Some of the signs include:

Separation of the oil from the thickener
Change in the consistency of the NLGI grade.

Ideally, we should check the expiration date on the packaging and contact the lubricant manufacturer.

We must note that if the packaging has been removed or opened in some way, the expiration date may not be valid.

The expiration date on the product is the approximate shelf life of the product should the packaging remain intact and if stored in the recommended environment.

If these are compromised then the validity of the expiration date has also been compromised.

Storage and Handling / Strategic Tips

Outdoor Storage

I have no room in the warehouse, can I store the oils outside until I get room?

It is never ideal to store lubricants outside exposed to the elements. However, there may be situations where this cannot be helped.

For instance, transformer oils are very sensitive to light and water.

If there is an option of at least storing one type of oil away from the elements, then this type of oil is at the top of the list.

If it has to be stored outside, then there are some measures that can be taken to ensure it is not compromised.

We can place a tarp over the product to ensure that the rain does not settle on the drums and they remain fairly dry.

They can also be stacked on pallets, so that they are not directly touching the ground. This way, water cannot enter the product.

Additionally, they can be stored such that the bungs are at a 9 or 3 o’clock position. In this position, if water falls on the top of the drum, it cannot accumulate by the bungs and seep into the product.

Once the packaging has been opened, the product can be considered open to contamination and anything that gets into the product will eventually get into the equipment.

Ideally, opened products should be stored in enclosed areas or have dedicated decanting systems.

Industrial / Strategic Tips

ISO 4406 rating

Is the ISO 4406 rating important?

Yes, it is very important!

The ISO 4406 rating tells us the cleanliness level of our lubricant. It tells us the number of particles that can pass through a 4, 6 and 14 micron rating.

However, the value on the ISO rating does not represent the number of particles. On the contrary, it represents the range in which the number of particles can lie.

One key point to remember is that the rating will always change from the time that the sample was taken to the date that the results were processed.

Therefore, it is a good idea to use the sample result as a guide as estimate a bit higher for the real value of your lubricant.

Check out our article which goes into more detail about ISO 4406.

Matt Spurlock CLS, CMRP, MLE explains further about redefining the ISO code in his article entitled; "A Twist on Particle Evaluation: Redefining the ISO Cleanliness Code".

Industrial / Strategic Tips

Filter rating

Is the filter rating important?

Yes! It is very important.

Usually, the OEM of the equipment specifies the filter rating (and even the filter material in some cases). These ratings help us to keep out particles of larger sizes that may cause damage to the equipment either through wear or clogging of fine clearances.

Some filters allow us to monitor the differential pressure. This is the pressure between the outside of the filters and inside and as this approaches the warning limits, we know that a filter change is needed in the near future.

However, there are times when there is no warning and the filter goes into bypass. When a filter goes into bypass, this means that the filter is no longer keeping back the larger particles. This can be catastrophic for the equipment as a higher concentration of contaminants can now enter the system and damage it.

It is common practice to change the oil filter when the oil is being changed. In some instance, (especially depending on the environment), OEMs recommend changing the oil filters twice or more before the actual oil change.

Always consult with your owner’s manual about the maintenance practices before adopting your own.

Industrial / Strategic Tips

Synthetic vs Mineral

Should I use a synthetic oil in my equipment or just stick to mineral?

Check with your OEM first.

There are some OEMs that require a synthetic to be used but others that prefer mineral oils.

Typically, a synthetic oil (in industrial applications) tends to have longer operating hours compared to that of a mineral oil.

As such, lots of companies prefer to use synthetic oils as it leads to cost savings in the long term.

However, there are times when mineral oils are more cost effective.

For instance, if the component has to undergo maintenance (where the oil has to be drained) every 500 hours then it would not make sense to have a more expensive oil that lasts for 2000hours.

Before choosing whether mineral or synthetic, we need to do a cost benefit analysis of using both and then make an informed decision. If we can see savings by switching to a synthetic (such as energy, fuel or manpower savings) then this is definitely the way to go.

Industrial / Strategic Tips

Mixing viscosities

Can I mix different viscosities of oils to get the viscosity that I want?

It can be done but this is not an ideal situation.

There are times when the only available viscosity is an ISO 46 (on a rig) but the equipment requires an ISO 68 and the new stock will not be delivered in time to avoid shutdown. Can the ISO 46 be used instead?

An ISO 46 oil is lighter in viscosity than an ISO 68 however, for most oils, there is a chart that depicts the viscosity of the oil at operating temperature. In these cases, one can consult this chart and determine if the viscosity at operating temperature will still fall within operating limits.

If we mix an ISO 46 with an ISO 68 oil we cannot be certain of where the new viscosity will fall especially if we do not know the ratios that are being used. There is a viscosity calculator that can help guide this decision available at: https://www.widman.biz/English/Calculators/Mixtures.html

This can be used as a guide and the actual values of the oil should be verified via oil analysis.

While this situation is not ideal, we need to remember that compatibility is also key.

As such, we should stick with the same line of lubricants that we being used. Typically, lubricant suppliers have the same formulation but change the viscosities for lubricants of the same line.

Tagged: lubricants