Category: Strategic Tips

Food Grade Lubricants

Food_grade

Q: What are the classifications for Food grade lubricants?

If you’ve ever dealt with food grade lubricants in the past, you would have noticed that not all food grade lubricants are made to the same standard. When we think about it from a manufacturing standpoint, we can understand the need for varying specifications.

For instance, in a facility there are components that will come into contact directly with the food while there are others that will never make contact with the product being produced for consumption. As with all specifications, the prices of the lubricants created for regular non-food grade usage will differ from those that are specifically designed for food grade usage.

NSF Standards

NSF International is the body responsible for protecting and improving global human health. They also facilitate the development of public health standards and provide certifications that help protect food, water, consumer products and the environment.

Here are the different specifications for each of the food grades (used in most countries)1:

NSF H1 – General or Incidental Contact

NSF H2 – General – no contact

NSF H3 – Soluble oils

NSF HX-1 – Ingredients for use in H1 lubricants (incidental contact) [usually additives]

NSF HX-2 – Ingredients for use in H2 lubricants (no contact) [usually additives]

NSF HX-3 – Ingredients for use in H3 lubricants (soluble contact) [usually additives]

 

Usually using a NSF certified lubricant goes hand in hand with an HACCP based food safety program (Hazard Analysis and Critical Control Points).

 

ISO standards

There are ISO standards that govern food safety. These are;

ISO 22000 – developed to certify food safety systems of companies in the food chain that process or manufacture animal products, products with long shelf life and other food ingredients such as additives, vitamins and biocultures2.

ISO 21469 – specifies the hygiene requirements for the formulation, manufacture and use of lubricants that may come into contact with products during manufacturing2.

 

 References:

  1. Quick Reference Guide to Categories, NSF USDA. https://info.nsf.org/USDA/categories.html#H1
  2. International Regulations for Food Grade Lubricants. Richard Beercheck. Lubes N Greases Europe- Middle East-Africa. June 2014. https://d2evkimvhatqav.cloudfront.net/documents/nfc_int_regulations_food_grade_lubricants.pdf?mtime=20200420102000&focal=none

FZG Ratings

FZG

Q: What does FZG mean and why do gear oils have a rating?

FZG stands for “Forschungsstelle für Zahnräder und Getriebebau”, Technische Universität München (Gear Research Centre, Technical University, Munich), Boltzmannstraße 15, D-85748 Garching, Germany.

There are several FZG tests and these vary to establish different things. We will explore the two most common tests and what they mean.

The FZG tests were designed to accurately determine the types of gear failures that were influenced by scuffing, low speed wear, micropitting and pitting1. While there are load other tests for gear oils (such as Timken OK test) these do not accurately identify the actual failure stages that gears experience.

FZG A/8.3/90

One of the most commonly used FZG test is the FZG A/8.3/90 according to DIN ISO 14635-1. This is mainly used for evaluating the scuffing properties of industrial gear oils2. What do the numbers in the test mean?

The “A” represents an A-type gear with Pinion face width = 20mm, center distance = 91.5mm, number of teeth (pinion) = 16, number of teeth (gear) = 24. These are used in the test and are loaded stepwise in 12 load stages between Hertzian stress of pC= 150 to 1800N/mm2.

The “8.3” represents the pitch line velocity of 8.3m/s in which the gears are operated for 15 minutes at each load stage.

The “90” indicates the starting temperature of the oil (90°C) in each load stage under conditions of dip lubrication without cooling.

After each load, the gear flanks are inspected for scuffing marks. However, the fail load stage is determined when the faces of all pinion teeth show a summed total width of damaged areas which is equal or exceeds one tooth width. In the gravimetric test, the gears are dismounted and weighed to determine their weight loss.

 

FZG A10/16.6R/90

The FZG A10/16.6R/90 on the other hand is used for automotive gear oils (GL4). It is the standard FZG gear rig test but the speed, load, load application and sense of rotation have been slightly altered.

The “A” represents an A-type gear however, these now have a reduced pinion face width to 10mm (from 20mm above).

The “16.6R” represents the increased speed of the pitch line velocity of 16.6m/s in which the gears are operated for 15 minutes at each load stage in a reversed sense of rotation.

The “90” indicates the starting temperature of the oil (90°C) in each load stage under conditions of dip lubrication without cooling.

 

FZG S-A10/16.6R/90

However, the FZG S-A10/16.6R/90 is the shock level test done for the GL5 oils. In this test the gears are directly loaded in the expected load stage and a PASS or FAIL is issued.

 

References:

  1. ISO 14635-1:2000 Gears- FZG test procedures- Part 1: FZG test method A/8,3/90 for relative scuffing load carrying capacity of oils.
  2. Test methods for Gear lubricants. Bernd-Robert Hoehn, Peter Oster, Thomas Tobie, Klaus Michaelis. ISSN 0350-350X GOMABN 47, 2,129-152 Stručni rad/Professional paper UDK 620.22.05 : 621.892.094 : 620.1.05

Flender Specs

Flender

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:

  1. Mineral oils (API I & II and ester oils) shall be 10,000 operating hours (2 years max)
  2. Mineral (API III) and Synthetic (PAO & PAG) oils shall operate for 20,000 operating hours (4 years max)
  3. 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:

  1. FZG Scuffing test in accordance with DIN ISO 14635-1 (A/8.3/90)
  2. FE8 rolling bearing test in accordance with DIN 51819-3 (D-7, 5/80-80)
  3. FVA micropitting test FV A 54 VII
  4. Flender oil Foam test in accordance with ISO 12152
  5. Compatibility with internal coating
  6. Compatibility with outer coating
  7. Filterability test FFT 7300 Rev.3
  8. 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:

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

Lubrication Regimes

Regimes

Q: Is there only one type of Lubrication regime?

There are actually 4 types of lubrication regimes that equipment can experience and each component usually experiences at least 3 within their lifetime!

As per Noria 2017, the four different types of lubrication are; Boundary Lubrication, Mixed Lubrication, Hydrodynamic Lubrication and Elastohydrodynamic Lubrication.

Essentially, the best type of lubrication regime is Elastohydrodynamic as it provides the most ideal environment for both the lubricant and the surface. However, there are instances where other types of regimes can exist due to a lack of lubricant or contaminants.

Most components experience Boundary Lubrication on start up where there isn’t a proper layer of lubrication between the two surfaces. As such, the asperities of the two surfaces touch and can create wear. When we look at surfaces under a microscope, we can see tiny asperities (which we can liken to sharp or jagged edges) which are prevalent along the surface.

Even though a surface may appear shiny and smooth, when we microscopically examine them, the actual surface has a lot of asperities. Imagine, if two rough surfaces were sliding against each other, like a piece of sand paper against a wall, eventually parts of the wall will be removed due to the asperities of both the sand paper and the wall.

As more oil is gradually introduced to the component, it begins to experience Mixed Lubrication. In this state, the oil film is still not fully formed and is a bit thicker in some places than others. There are some contact areas where the surfaces will still experience boundary lubrication as well as elastohydrodynamic or hydrodynamic lubrication.

During this period, wear occurs due to the areas that are still experiencing boundary lubrication. However, it can be considered a transition phase as the surfaces move from tone type of regime into another as the lubricant film gradually increases.

When the component is full immersed in the lubricant, it usually achieves Hydrodynamic Lubrication which allows for a full film to be formed between the two surfaces and there is no longer any contact with the asperities. This is one of the most ideal forms of lubrication as it greatly reduces the wear between the two surfaces and the oil film safeguards that these can easily slide over each other thus, decreasing the friction between them. In this type of lubrication, the oil wedge is maintained in all operating conditions and guarantees that the asperities of both surfaces do not interact with each other.

On the other hand, with Elastohydrodynamic Lubrication, something quite special occurs with the lubricant causing the component to deform slightly ensuring that the film is maintained between the two surfaces. This happens at the highest contact pressure and ensures that the asperities do not touch whilst maintaining the oil wedge.

This type of lubrication usually occurs when there is a rolling motion between two moving surfaces and the contact zone has a low degree of conformity (Noria. 2017). Essentially, Elastohydrodynamic lubrication occurs when the lubricant allows the contact surface to become elastically deformed while maintaining a healthy lubricant film between the two contact surfaces.

 

References:

Noria Corporation. 2017. Lubrication Regimes Explained. https://www.machinerylubrication.com/Read/30741/lubrication-regimes

 

EALs?

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;

  1. Speed at which the lubricant biodegrades if introduced into nature
  2. Toxicity characteristics that may affect bacteria or aquatic life
  3. 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;

  1. Primary biodegradation - loss of one or more active groups renders the molecule inactive with respect to a particular function
  2. 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:

  1. 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
  2. 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:

  1. Vegetable Oils
  2. Synthetic Esters
  3. 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 test 1.

 

References:

  1. Lubrication Fundamentals Second Edition, Revised and Expanded. D.M. Pirro (Exxon Mobil Corporation Fairfax, Virginia), A.A. Wessol (Lubricant Consultant Manassas, Virginia). 2001.
  2. 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
  3. Chemistry and Technology of Lubricants 3rd Edition, Chapter 1, R.M. Mortier, M.F. Fox, S.T. Orszulik)

Base Oil Groups

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).

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:

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

PAOs vs PAGs

PAO_vs_PAG

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 s 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:

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

Expired grease?

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.

Outdoor Storage

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.

ISO 4406 rating

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". 

 

ISO-4406-chart