Twenty years of innovation continues with breakthrough in food grade lubricating fluids

Over the past 20 years, every product in Petro-Canada’s PURITY FG line of food grade lubricants has been formulated to excel under difficult plant conditions, while meeting high safety standards.

Petro-Canada has a unique line of white oil based food grade (FG) lubricants including compressor, gear, hydraulic, chain, trolley and heat transfer fluids. Select products include Microl - the first EPA registered antimicrobial preservative for food grade lubricating fluids. Synthetic gear and compressor fluids extend the line for low temperature and specific applications.  

The high performance of the PURITY FG line of products can be attributed to accumulated formulating experience, using base oils made by the patented hydro-treating (HT) purity process to remove impurities that could hinder performance and additives that are specially selected and uniquely combined to provide the utmost benefit to these highly processed mineral oils.

New product opportunities and improvements to the current PURITY FG line are always under review.  Improving the oxidation stability of Petro-Canada's fluids in order to make them last longer has always been at the forefront of our design considerations. 

To that effect, PURITY FG compressor fluids use a patented anti-oxidant combination to provide excellent oxidation stability and clean performance.  Not only has this been shown in laboratory tests, but also in over 15 years of rotary screw, vane and reciprocating compressor service and vacuum pump applications in food processing plants. 

Focus on tough food plant conditions

The processes and conditions in food plants are tough. Processing equipment must endure the stresses placed on it. 

Wet and humid conditions from climate or cleaning methods, and start-stop operations provide yet another challenge to lubricant design to ensure sufficient corrosion control, foam dispersion, and water separation. 

The oxidative stability demands on compressor lubricants become greater as operations grow larger requiring greater volumes of air to operate pneumatics, as process shifts are extended and as compressor design itself becomes more compact with a smaller footprint.

Compressors needing to run over longer time periods may result in hotter discharge temperatures. One factor causing this may be insufficient cooling of the oil. Oil residence times in the sump may be shorter due to system design and/or cooling systems that may prove less efficient due to climate conditions - such as increases in the ambient room temperature or warming of the oil-cooling water. These conditions cause the rate of oil oxidation to increase as the temperature of the oil rises.  

Further, equipment operating over long time intervals draws in a greater volume of air and concentrates any air borne contaminants-  such as fats and oils from food processes  or cleaning acids from sanitation procedures.  Both circumstances increase the oxidation of the lubricating oil. 

As the oil oxidizes, the more viscous oil becomes harder to cool, harder to circulate, and can lead to deposits, varnish and eventually a difficult clean out of the equipment when an oil change is made.

In compressor fluids, the importance of a fluid's oxidation stability to ensure smooth operation for lubrication, sealing and cooling is high.  

Improving resistance to oxidation

The choice of additives and their permitted concentrations in lubricants with incidental food contact are restricted by Food and Drug Administration (FDA), Canadian Food Inspection Agency (CFIA) and various other government bodies. However, loading up a formulation with the maximum quantities of the available additives does not necessarily result in a top-out of oxidation stability and can in fact be detrimental to overall product performance. There are very few opportunities to dramatically improve the performance of already good food grade products while keeping price in measure. That is, until recently.

Building upon the unique anti-oxidant chemistry of  Purity FG Compressor Fluids, a leap in the level of oxidative resistance is provided with breakthrough technology to yield a significant improvement in performance.    

Petro-Canada's new and improved Purity FG Compressor Fluids deliver a dramatic improvement in oxidation stability for robust service in today's harsh food plant environments.

New and improved compressor fluid

Laboratory tests show significant improvement in relative control of oil thickening of the New and Improved Purity FG Compressor Fluid in response to heat and high air flow exposure (Figure 1).

Fluid thickening with oxidation

IP48/97 (modified) oxidation test, 24 hours 200°C (392°F), 15 L/hr air

Figure 1: The viscosity increase is significantly less for the new formulation.

Rotating Pressure Vessel Oxidation Test (ASTM D2272) confirms this improvement in the resistance to oxidation. Compared to the original formulation, almost double the time is necessary to observe the required 25.4 psi O₂ pressure drop in the vessel signalling the end of the test. Isothermal Pressure Differential Scanning Calorimetry, PDSC (200°C) studies further confirm this product enhancement.

As an added benefit, an improvement in anti-wear properties is observed for better protection of rotor bearings within rotary screw compressor units, or vane tips as they contract and expand against the housing in vane compressors, or piston rings and liners in reciprocating units.   

Improvement in one property can sometimes cause deficiencies in others. Fortunately, tests revealed the same excellent control of deposit build-up as apparent for the original product (Figure 2).  

Deposit Formation -Panel Coker Test, 260°C (500°F),

 16 hours, oil flow rate 2.3 mL / hr

Figure 2: Clean test panels are observed for the New and Improved Purity FG Compressor Fluid and the original formulation. In contrast, competitive products tested show deposits on the panels.

As well, good corrosion inhibition is maintained with the new fluid, which is important when running equipment in intermittent service in high humidity conditions.

Given the dramatic improvement in oxidation stability of the New and Improved Purity FG Compressor fluid, comparisons of oxidation resistance against other FG products both mineral oil based (MO) and synthetic (Syn) were made.

Lab results have shown us oxidative stability mostly comparable to better than the competitive fluids tested (Figures 3, 4).

Figure 3: RPVOT (ASTM D2272), time to 25.4 O₂ psi pressure drop.

Figure 4: PDSC (200°C), oxidation induction times (OIT) observed.

Exceptional lab results have provided confidence to test this formulation in a non-food industrial application using a two stage double screw rotary compressor (two compression stages), in a tough industrial operating environment. The test revealed good performance of the fluid.    

What can you expect?

New and improved Purity FG compressor fluids are the result of breakthrough FG technology that builds on our already excellent properties and provides significantly stronger lubricant performance and durability.

A robust fluid, this new and improved fluid with its strong oxidation stability can be used in more severe applications, hotter conditions, more difficult environments, more oxidatively stressful operations than our current product. With significant improvements in oxidation resistance over our already highly oxidatively stable product, expect better performance over the long term. 

Although the inherent oxidation stability of the lubricant is important, to keep any equipment in top working order good maintenance practices, including the provision for adequate oil-cooling and air filter element replacement, need to be followed. Oil condition monitoring should be part of a preventative maintenance schedule.

New and Improved Purity FG Compressor Fluids 32, 46, 68 and 100 fit perfectly in HACCP (Hazard Analysis and Critical Control Point) and GMP (Good Manufacturing Practice) plants. All fluid components comply with FDA regulation 21CFR178.3570 "Lubricants with incidental food contact". All fluids are H1 registered by NSF.

Biography

Dr. Inga Kuksis is a Product Specialist in the Research and Development group of Petro-Canada Lubricants. Over 10 years at Petro-Canada, her work has involved the development of new products as well as the technical and quality support for the fluids in the portfolios she has overseen. These have included heat transfer fluids, food grade lubricants, gear and windturbine fluids, as well as air and natural gas compressor oils.

Dr. Kuksis was recognized as a finalist in the Best Product Development Team category for the International Stevie Business Awards in 2007 . She was a key member of the Petro-Canada team responsible for winning the top International Stevie Business Awards for Best New Product or Service in both 2007 and 2010. 

Dr. Kuksis received her Ph.D. in Organometallic Chemistry from Queen's University in Kingston, Ontario. Her BSc. in Chemistry and Human Biology is from the University of Toronto. A member of the Society of Tribologists and Lubrication Engineers, she has presented papers at both national and section meetings.