In September’s first installment of the Fluid Power Technology 2020 Virtual Series, Brandon Richards, CEO of PANOLIN America Inc. presented “Where and when should you use environmentally acceptable fluids?” He provided an overview of the types EALs available in the marketplace and benefits of these fluids over mineral-based lubricants. Here are some highlights.
To truly be sustainable, EALs have to address three issues: technology, environment, and economy. Fluids suppliers must provide a technically mature product that offer high performance, durability and long life, with excellent oxidation stability, and wear and corrosion protection.
Second they must be environmentally friendly in terms of biodegradability, low toxicity, and CO2 reduction. And third, economical. Products must be affordable, and serve as an investment that will pay you back over the lifetime of the fluid. Total cost of ownership is much lower with some EALs as opposed to others.
Facts versus jargon
So what are EPA requirements for a fluid to be considered an EAL? Let’s start with important terminology.
Biodegradability is the measurement of the breakdown of a product’s chemical structure by microorganisms and the environment. ASTM 5864 standard classifies the rate at which products biodegrade. Inherently biodegradable products break down 20% in 28 days. Readily biodegradable products break down three times faster, 60% of the product biodegrades in 28 days.
Aquatic toxicity is the measurement of how lethal the product is to aquatic life such as algae, daphnia (small crustaceans) and fish.
Bioaccumulation is the buildup of chemicals within the tissues of the organisms over time that passes from one organism to another via the food chain. For example, if a product introduced into a lake poisons plant life, which in turn is eaten by minnows and then larger fish, that is bioaccumulation.
So what are the hard and fast rules? The EPA says an EAL fluid must be readily biodegradable (remember, 60% biodegradation in 28 days), be minimally toxic and must not bioaccumulate. These are the three hard and fast rules.
There is creative marketing out there, so be careful. Many products on the market claim to be EALs, but are not. You have to be a smart consumer. Companies tout their products as green, environmentally aware, environmentally friendly or biodegradable, but that doesn’t mean it’s readily biodegradable. Also, food-grade products are not necessarily biodegradable.
Types of EALs
Let’s look at the types of EALs. According to the ISO 15380 specification, there are different base-oil classifications:
HEPG are polyglycols (PG) and polyalkylene glycols, commonly known as PAGs, and are synthetic products. PAGs offer good oxidation stability but poor compatibility with seals, hoses, paints and, definitely, other lubricants. PAGs are only compatible with other PAGs. If your system runs low and needs a top up, if you don’t have a PAG on board, you’re out of luck. You cannot use a different type of product.
Incompatibility with other fluids leads to high conversion costs. When you switch from a non-EAL product to an EAL, you have to flush and fill your system. Due to HEPG incompatibility with other fluids, the user must ensure that there is absolutely 0% of leftover product.
These are water soluble products and do not separate from water. That can lead to rust, corrosion and, in some instances, bacterial growth. As you can imagine, hydraulic systems are dark and warm, and they’re a perfect breeding grounds for bacteria. So be very careful. These are disposable products and the EPA states they are the absolute most-expensive to convert.
HETG are triglycerides, natural vegetable oils like canola and rapeseed oils. This is the classification that people commonly deem as all biodegradable lubricants. This is very far from the truth. These natural esters typically have a high iodine number, consistent with unsaturated esters. They have good biodegradability, but poor performance especially at high operating temperatures. The products are prone to oxidation and breakdown, generating deposits, blocking filters and reducing system efficiency. They are typically less expensive but require frequent oil changes. They are not suitable for mid- and high-performance equipment. This is a product that the EPA states as having major performance drawbacks.
HEPR are based on polyalphaolefins, or PAOs, and related synthetic hydrocarbons. PAOs offer good oxidation stability and are great lubricants. PANOLIN offers PAOs, but not necessarily for biodegradable use. Only a PAO2 with a viscosity of 10 or lower is considered biodegradable. Typical industry applications run fluids from 32 to, let’s say, 68 viscosity.
To use a PAO as an EAL, typically, these products are mixed with unsaturated esters or viscosity index improvers. The result is a non-homogenous mixture that is prone to shearing — basically the breaking apart of the product due to heat and pressure — with major efficiency losses. So this is a low-viscosity product that can permit leakage past seals and chattering in valves and cylinders. While this is a disposable product, it’s a commodity, not an asset. According to the EPA, this is not on the EAL list, so PAO is not an option.
HEES. There are two distinct types of HEESs, saturated synthetic esters and unsaturated synthetic esters, with two very different performance levels. PANOLIN’s technology is based on fully saturated, synthetic esters. These are top-performance products with great biodegradability and ecotox values. They have compatibility similar to regular synthetic lubricants regarding seals, paints, and so on, with high oxidation resistance and shear stability.
This extremely durable product is not water soluble, so water that gets in will separate and can be drained from the bottom of the tank when the system is at rest. PANOLIN ester technology is suitable for a lifetime fill and keeps machines up and running. It’s an asset, not a commodity.
Unsaturated synthetic esters typically are lower performing fluids, with performance levels closer to triglycerides for oxidation stability or thermal stability. They tend to form deposits, shellac and lacquer, so there are numerous ways that the fluid can shut down a system or degrade efficiency.
Synthetic esters vs. mineral oils
Let’s now talk specifically about PANOLIN saturated synthetic esters (SSEs), and compare them against mineral oils. PANOLIN SSE costs more than mineral oil, but it is a higher performance product that will last considerably longer.
In terms of viscosity and temperature characteristics, SSEs at least double the performance of mineral oil. For low-temperature performance. PANOLIN’s HLP SYNTH has a pour point of around -70° F. So very good performance at low temperatures. In high-heat applications, mineral oils will evaporate, PANOLIN SSEs will not. They handle higher maximum temperatures with higher oxidation resistance. Lubricity is better. And again, these products tend to last longer, so you’re not regularly changing the oil. Some mineral oils can be considered as inherently biodegradable; PANOLIN saturated synthetic esters are readily biodegradable.
Now let’s talk about water. A big question is what happens when water gets in? Well, water ingression in a hydraulic system is far from ideal, as it is not a lubricant. The saturation point of PANOLIN SSEs is much higher than it is in a mineral oil. Mineral oils typically become saturated at anywhere from 200 to 500 ppm, as opposed to SSEs at around 1,000 to 1,500 ppm.
So we can take on a lot more water. Nonetheless, too much water combined with heat and pressure can lead to hydrolysis, which is common for all esters. So it is important to control the water. The byproduct of hydrolysis is an increase in total acid number, and it’s understood that a TAN increase is an indicator for the life of your oil. It’s important to note that PANOLIN SSEs can have a much higher TAN value before needing to be replaced. Mineral oils need replacement when TAN = 2; a saturated synthetic ester can last to TAN = 5, and sometimes higher.
As confirmation of success, PANOLIN HLP SYNTH has received approvals from many major hydraulic component manufacturers such as Danfoss, Eaton and Parker, along with numerous mobile-equipment and marine OEMs. Of particular note is that HLP SYNTH is the only EAL hydraulic oil to make the Bosch Rexroth RDE 90245 Fluid Rating List. This is an extremely stringent series of tests to certify the compatibility of a fluid with the company’s high-end pumps and motors.
This really stands to support our performance. These products are very robust and believe me when I say, Bosch Rexroth really puts this product through its paces. This is, again, a very big feather in the PANOLIN cap.
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