Two aspects of filtration have a direct impact on the environment: first, filters are frequently used to extract contaminants from liquids and gases so that they do not pollute; second, the filter elements - which are inevitably contaminated - have to be safely disposed of at their end of their useful life so that they do not pose a fresh hazard.

Filter manufacturers have always worked hard to ensure that their products perform efficiently, effectively and are reasonably priced. However, the question of how to dispose of the filter element has seldom received as much attention.
Parker Filtration, part of the worldwide Parker group, has been looking into this and recently launched the Leif (low environmental impact filter) concept that is incorporated into products such as the Multiflow Size 1, 2 and 3 tank-top mounted return line filters for industrial and mobile hydraulic applications. In addition to the Leif elements, the Multiflow filters also benefit from an optional reusable conversion sleeve (chimney).
Contaminated filter elements are often classified as chemical waste, resulting in high disposal costs for end users when changing filters. But by re-using the metal sleeve, this component no longer needs to be disposed of, leaving only the contaminated filter media to be treated as chemical waste. The weight of the disposed media is therefore small and oil can easily be removed from the element, resulting in an even lower weight and volume. Depending on the circumstances, Parker claims that the disposal and processing costs can be reduced by 50 per cent and, as a result, a lower cost of ownership can be realised.
The same Leif concept has also been used in Parker's latest SR2 suction and return filters that supply filtered return oil from the open operating hydraulic system to the boost pump(s) of a hydrostatic transmission under a positive pressure (Fig. 1). In particular, the SR2 meets the requirements of OEMs (original equipment manufacturers) using closed-loop systems for hydrostatic drives and open operating systems - for example, in telescopic handlers, wheeled loaders and agricultural equipment.
Another area in the field of hydraulics where Parker has been developing 'greener' products is in air breathers. The EAB Series and the ABL Series both feature the company's E-Series environmentally-friendly elements that are designed to reduce waste and environmental impact in disposal (Fig. 2). Typical applications for these air breathers include agricultural machinery, sawmills, articulated dump trucks, forestry equipment, wheeled loaders, lubricating systems, excavators, mobile cranes and industrial power units.
Most air breathers currently available contain a cellulose filter medium. In many cases, however, the micron rating of these breathers falls short of the required system cleanliness. Relatively large dirt particles can therefore enter the hydraulic system and subsequently need to be filtered out again.
Parker has developed two E-Series element options to give flexibility and reliability within the concept of environmental protection: Leif is a design utilising metal mesh media supports; and Ecoglass III uses a disposable mesh both upstream and downstream of the media. The E-Series element options are both totally disposable. Leif elements can be crushed and incinerated, then the media support mesh can be separated out magnetically, offering reduced bulk for disposal and recycling of the material.
With the 3-micron Leif glass fibre filter element and the 1- and 2-micron Ecoglass elements, cleanliness of the incoming air is strictly controlled. This, in turn, improves the cleanliness of the system and, over time, contributes to the increased lifespan of various system components.
Ecoglass III can be crushed, shredded and baled which, combined with incineration, offers minimal residue and causes little or no damage to the environment. The new EAB Series air breather uses EcoglassIII media and is designed to achieve a low pressure drop and high dirt holding capacity with airflow up to 1500l/min.
In the mid-1990s, concerns about emissions from large engines led to Parker developing the Racor crankcase vent (CCV) system (Fig. 3). This offers more than just a way of cleaning up the engine room: with high levels of filtration down to sub-micron size, it protects the engine from the particles of oil that are easily let through by other filter systems, thereby protecting the engine from a potential loss of performance and possible damage. In addition, the CCV may reduce engine exhaust emissions by lowering the amount of oil that becomes mixed with the air when fed back into the induction system. Oil is always present in the combustion chamber regardless, because of the forced lubrication system; however, because the oil from the crankcase is a vapour it is more easily combusted, leading to an increased NOx and soot content from the exhaust.