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Plastic Pellets Replace Harmful Chemical Cleaners

09 Aug

source: http://www.armee.forces.gc.ca/lf/English/1_8_3_4.asp

Environmental Success Story At Land Force Québec Area (LFQA)

AIM

Every day, the Canadian Forces (CF) face the challenging goal of exercising environmental stewardship while maintaining rigid military standards. A good example of that would be the implementation of pollution prevention programs, such as the one developed at Area Support Unit (ASU) Valcartier.

INTRODUCTION

Solvent cleaning or chemical stripping was, at one time, the primary method used to prepare aircraft parts for inspection and painting.Solvent cleaning or chemical stripping was, at one time, the primary method used to prepare aircraft parts for inspection and painting. However, toxic properties of methyl ethyl ketone (MEK), the main substance used to clean aircraft parts, posed a significant environmental threat. In addition to being a known health hazard, MEK also contributes to the problem of hazardous waste disposal. In an effort to prevent environmental pollution, officials opted to replace chemical stripping with a less harmful method.

FACTS

Issue

MEK, which is a volatile and highly toxic substance, is used in the heliport’s paint shop at ASU Valcartier as paint thinner or wipe solvent to strip aircraft parts before inspection and painting. The cleaning and removal of tailings was a painstaking process and was becoming more and more costly. ASU Valcartier’s heliport was using up to 2 300 litres of MEK each year.

There was a need to replace chemical stripping with an alternative process. In addition to the costs of the stripping process, the amount of water and solvent consumed continued to escalate. Because of its carcinogenic nature and the ever-increasing generation of hazardous wastes, there was a need to replace chemical stripping with an alternative process.

Options

At a time when technological progress allowed for environmentally friendly means of paint removal, consideration was given to methods that did not employ chemical solvents. These new methods had to limit health risks arising from exposure to chemicals, reduce costs associated with cleaning and greatly minimize the negative environmental impacts. After an in-depth review process and exhaustive testing, the cleaning process found to be the most efficient was abrasive ball blast cleaning using special plastic pellets as the cleaning media. A machine that works like a sandblaster (except the sand is replaced with plastic pellets) removes paint without damaging the metal.

Advantages

Replacing solvents with a machine that uses plastic pellets has many advantages. By not using a solvent for stripping, the operator is not exposed to chemical agents and the risk of fire is reduced. The equipment is easy to maintain, the plastic pellets can be recovered and the mechanical components are easily accessible. The equipment does not take up a lot of space and a silencer installed on the machine keeps noise levels down. The Department of National Defence has approved the use of the plastic pellet blasting technique and it is already used at many military and civilian aircraft maintenance sites.

Results
Mechanical cleaning proved to be quicker and cheaper.
Mechanical cleaning proved to be quicker and cheaper. As an example, to clean one wheel of a CC-130 Hercules cargo transport aircraft, it usually took 20 to 30 litres of solvent and one week of work. Doing the same job using ball blast cleaning takes only three hours and no solvent is used.

However, dry stripping cannot completely replace chemical cleaning. The size of the aircraft parts to be cleaned limits its use. In fact, the pellet-blasting machine can only accommodate about 30 percent of the parts that need to be cleaned. Nevertheless, this new method allows a decrease of nearly 600 litres of solvent per year, compared to the original annual consumption of 2 300 litres of MEK at Valcartier’s heliport.
Mechanical blast cleaningAlso, chemical stripping contributes to the costly problem of cleaning up and disposing of large quantities of mixed liquid and solid, organic and inorganic hazardous waste. Mechanical blast cleaning, on the other hand, produces about 68 kg per month of solid waste only. The dry stripping apparatus separates the plastic media by weight differential. The plastic particles are recovered and reused at least 15 times. As a result, dry stripping significantly reduces hazardous waste disposal costs.

CONCLUSION

The ball blast cleaning method is a sound alternative to chemical stripping. In the context of pollution prevention, mechanical cleaning is efficient and is the preferred choice in that it significantly reduces risks to human health and the environment. It is also cost-effective and saves valuable floor space.

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Posted by on August 9, 2007 in General Knowledge, R&D

 

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