There is growing concern over the environmental impact and associated costs of lost petroleum based fluids. Petroleum is persistent and toxic; it damages living organisms including plants, animals and marine life for many years. In addition, regulatory agencies are increasing the range of responsibility of lubricant releases including significant fines and clean up costs.

As environmental enforcement agencies increase pressures and costs for petroleum lubricant spills, many crane owners and operators are using or considering environmentally safer products. These types of fluids can protect the users against fines, cleanup costs and downtime, but care must be taken in selecting the right product for a specific application. Crane hydraulic systems typically operate at high temperatures, pressures and more severe duty cycles, and therefore require more durable fluids.

More and more owners, operators, and regulatory agencies are recognising the benefits of environmentally friendly fluids. Using these lubricants can save cane operator thousands of dollars in terms of fines, clean-up costs and down time.

Oil suppliers use different words to describe hydraulic fluids that offer environmental benefits including ‘environmentally safe’, ‘biodegradable’, ‘triglyceride (vegetable)-based’, ‘ester based’, ‘food grade’, and ‘synthetic’.

The table below outlines the performance of various fluids. Triglyceride or vegetable-based products and some synthetics are the most environmentally preferable. The so-called ‘environmentally safe’ products tend to be petroleum-based, and not biodegradable in the truest sense. Glycols and synthetic esters offer very poor elastomer and seal compatibility.

As demands on lubricant systems increase, the likelihood of accidental release of fluids increases.

The increased operating temperatures, pressures, and working cycles of cranes shorten the life of circuit components. The single best approach to protecting the environment, the equipment, and the operation is to prevent leaks and spills through good routine maintenance. A good preventative maintenance program will also increase productivity, better utilise in-shop maintenance, and improve control of spare part inventory.

Biodegradation is the chemical breakdown of a material into its natural components (see figure 1). For most materials – including lubricants – biodegradation requires air, water and micro-organisms. For this reason, well designed biodegradable hydraulic fluids do not degrade in the equipment or the storage container drums.

There are two commonly used measurements for biodegradation. The first is ‘primary degradation’, which measures reduction of the carbon and hydrogen bonds (C-H) in the initial solution; this is the reduction of the amount of the lubricant. The most widely used test that measures this decrease is the CEC-L-33-A-93.

The second measurement of biodegradation is ‘secondary’ or ‘ultimate degradation’. This measures the evolution of carbon dioxide (CO2) through the biodegradation. The usual test for this is the OECD 301or the ASTM D4684. Figure 2 shows the process.

There are two widely used designations for biodegradability – ‘readily’ and ‘inherently’. Readily biodegradable is degrading 80 per cent within 21 days as measured by the decrease of a test sample. This type of degradation is preferable because, in most cases, the fluid will degrade long before environmental damage has occurred. Because of this, it requires little in terms of long-term bio-remediation. Vegetable-based lubricants and some synthetic products exhibit ready biodegradation.

There are several petroleum-based lubricants that claim ‘inherent biodegradability’. These are typically referred to as ‘environmentally safe’. Inherent biodegradation is defined as having the propensity to biodegrade, with no indication of timing or degree. These types of products can persist in the environment for years. They require long-term remediation due to the environmental persistence. Typically, these products are petroleum-based, like conventional lubricants.

Looking at Figure 3, it is easy to see the difference between a readily biodegradable product and an inherently biodegradable one. Most regulatory agencies use this differentiation when evaluating an oil release.

Another measurement to determine environmental effect of a lubricant is ‘eco-toxicity’. Historically, tests for eco-toxicity have concentrated on the aquatic environment with a number of standard test procedures. Most typically, the tests are for ‘acute toxicity’ . This is a measurement of the concentration required to kill various organisms over a short period of time ranging 24-96 hours. Depending on the tests and its end points, the toxicity of a fluid is described by a loading rate that has a 50% effect (EL50) or causes 50% mortality (LL50) after the stated time. That is, at what concentration of fluid half the sample organisms die.

There is a wide variety of performance levels among biodegradable products. In the more severe applications in which cranes tend to be used, a biodegradable synthetic is usually required. While offering biodegradation, these products can operate in temperatures in excess of 400 deg F and still offer long fluid life. As would be expected, they are significantly more expensive. However, the extended fluid life can easily offset this cost.

Figure 4 illustrates the comparative oxidative stability of various readily biodegradable hydraulic fluids as compared with petroleum oil. As you can see, certain synthetic fluids (Biopolyolefin) will out perform petroleum.

Care must be taken in choosing the appropriate product for the specific application. Responsible environmentally preferable product (EPP) suppliers can clearly indicate their definition of ‘environmentally preferable’. Many ‘would-be’ EPP suppliers use misleading environmental claims such as ‘inherently biodegradable’ or ‘food grade’. Suppliers should be able to support performance claims with testing data.

While, in most cases, spills with readily biodegradable fluids are still reportable events, the resultant costs associated with the incidents are usually minimised. Since the fluids are biodegradable and non-toxic, there is no long-term negative effect to the ecosystem and fines, continual clean up costs, and downtime will be eliminated or reduced.

Regulatory agencies including the Marpol, MMS, Coast Guard, EPA, are increasingly recognising the environmental benefits of readily biodegradable products. They are aware that, in less than 30 days, spilled fluid will be reduced to safe, environmentally benign components (carbon dioxide and water). There is no long-term negative impact to the environment, and therefore no need for punitive fines. Frequently, an operator can continue working while rectifying the situation.

Another key aspect in assessing a spill related fine is negligence. When an operator is using a readily biodegradable product, regulatory agencies know that they are taking every precaution to not only protect the environment in the event of a spill but also to avoid spills in the first place. Readily biodegradable hydraulic fluids can cost three to five times as much as conventional petroleum based fluids. Obviously, an operator spending this difference is doing everything possible to prevent spills.

Long-term remediation and monitoring is usually very expensive. Since readily biodegradable products will dissipate within a 28-day window, there is no long-term clean up. Moreover, some of these fluids are vegetable-based and nontoxic and can provide a food source to the ecosystem.

True proof of performance is found in the field. Any fluid supplier should support its customers with routine oil monitoring and interpretation of the results. Since biodegradable products behave differently from conventional petroleum products, one should not count exclusively on the conventional oil analyst’s interpretation of test lab results.

It is important to partner with a biofluid supplier with enough field and technical experience to support an oil-monitoring program and to be willing and able to support product changes.

Readily biodegradable lubricants can save time, money and protect the environment. However, they must be properly maintained. Since the key to long fluid life and top tier performance is keeping the fluid clean and dry, proper filtration is essential.

Using a readily biodegradable hydraulic fluid is the right thing to do. It’s the right thing for clients, the right thing for the environment, and right thing for you.