Download the Alternative Supplier List opposite.
Solvents and Surface Cleaning
The use of large quantities of organic solvents for cleaning metal components both in manufacture and maintenance raises important environmental issues. Some solvents have been shown to contribute to ozone depletion in the upper atmosphere and some contribute substantially to hazardous ozone emissions at ground level and many have flammable and or toxic properties. There are also significant problems with contamination of groundwater.
As a result there are many laws which apply to the use of solvents in surface cleaning - it is important to check with your supplier what these are. These include laws made under the Montreal Protocol (such as EU Regulation 2037/2000 which has prohibited the use of 1,1,1 Trichloroethane). Changes in legislation could have implications for your supplier. Companies should ask their suppliers whether products may be subject to reclassification in future.
More recently the EU Solvent Emissions Directive (SED) has been implemented which sets emission limits for Volatile Organic Compounds such as solvents, according to various consumption thresholds. Also, significantly a common surface cleaning solvent - Trichloroethylene - has been reclassified as a (Category II) carcinogen increasing the controls required under the Control of Substances Hazardous to Health Regulations 2002. More information on the Solvent Emissions Directive and this reclassification is available from an HSE Engineering Information Sheet EIS 34 (see the HSE website opposite).
The Department for Food, Environment and Rural Affairs (DEFRA) has issued guidance on the implementation of the SED and the SED regulations.
Most surface cleaning operations fall within the scope of the new requirements.
Also a Hazard Assessment document has been published (EH75/3) by HSE on n-propyl bromide which concludes that, on the basis of the toxicology information currently available, it is very difficult to specify any particular level of inhalation exposure below which no health effects would be predicted to occur.
It has been agreed at the technical level within the EU that this substance meets the criteria for classification as Reproductive Category 2 R60 (may impair fertility, or cause damage to the developing embryo). However, this classification has to be confirmed through lengthy administrative procedures, the outcome of which is by no means certain.
Any volatile organic compound (solvent) used for surface cleaning in quantities of 2 tonnes or more p.a. is covered by the Solvent Emissions Directive for which you will need to meet an emission limit.
Any halogenated VOC (solvent) used for surface cleaning in quantities of 1 tonne or more allocated a risk phrase of R40 (Possible risk of irreversible effects) will need to meet emission limit requirements.
Any volatile organic compound (solvent) used for surface cleaning in quantities of 1 tonne or more p.a. and allocated one of the risk phrases below is also covered by the Solvent Emissions Directive for which you will need to meet an emission limit.
The Directive also requires the substance to be substituted in the shortest possible time (see below).
Guidance from Envirowise, the Government's best practice programme on the environment, clearly explains the options available for surface cleaning and sets out examples of good and best practice. See Envirowise guide GG354 'Surface cleaning and preparation: choosing the best option' (available from Envirowise by calling 0800 585794 or click on this link).
Guide to Suppliers of Cleaning and Degreasing Agents
This guide is essentially a list of suppliers of cleaning substances which may be used in place of those which are more tightly controlled by legislation. The list is not a recommendation of any company or product it is there to help source potential suppliers. When approaching any one of these suppliers you should ask whether the substance has been allocated any one of the risk phrases listed below.
R45 May cause cancer
R46 May cause heritable genetic damage
R49 May cause cancer by inhalation
R60 May impair fertility
R61 May cause harm to the unborn child
If the substance is classified with one of these phrases and it is used for surface cleaning then depending on the quantity used (i.e. 1 tonne or more p.a.) it will be covered by the Solvent Emissions Regulations for which you will need to meet an emission limit and more significantly will have to plan to substitute with a safer alternative, as far as possible, within the 'shortest possible time'. (Plans should have already been submitted to DEFRA).
Cleaning Methods
There are many different methods of surface cleaning including:
- mechanical surface preparation (e.g. sanding, blasting)
- solvent cleaning
- aqueous cleaning
- biological cleaning
- conversion coating
- combined cleaning and coating
These are outlined below and are described more fully in the Envirowise good practice guide GG354 'Surface cleaning and preparation: choosing the best option.' A table summarising the main advantages and disadvantages of the principal cleaning techniques is attached (Table 1).
NB. The method of solvent handling can significantly affect whether or not emission limits are met. Careless handling, or use of the wrong technique can mean limits are exceeded.
Mechanical surface preparation (e.g. sanding, blasting)
Mechanical cleaning techniques include brushing, blasting (dry, wet, air or wheel blasting). The Envirowise guide compares the different types of blasting and their main advantages and disadvantages.
Solvent cleaning
Solvent cleaning can be one of several approaches including wipe cleaning, vapour degreasing, conveyorised tunnel systems, immersion cleaning.
Other forms of cleaning sometimes included in this category are: ultrasonic cleaning, megasonic cleaning, spray cleaning (high or low pressure), power wash cleaning, steam cleaning, supercritical fluid cleaning, carbon dioxide 'snow' cleaning, ultra violet cleaning. The Envirowise guide compares the different types of cleaning and their main advantages and disadvantages.
Aqueous cleaning
Aqueous cleaning systems include a number of processes that use water, water based or semi aqueous cleaners either passively or physically. They may be described in five broad categories: pure water, neutral aqueous, acidic aqueous, alkaline aqueous and semi-aqueous. The Envirowise guide compares the different types of aqueous cleaners and their advantages and disadvantages.
Biological cleaning
Biocleaners are a well developed cleaning technology that have been shown to effectively clean oil and grease, paints and solvents from components. The two main categories are enzyme cleaners and surfactant/bacterial remediation systems.
There are also degreasing agents available which have been derived from plant oil (such as safflower, rape, linseed, cottonseed, and turpentine from pine trees). More recently the terpenes have come into use as solvents, they are non-toxic and readily degrade into the environment. Lemonene, found in the rinds of lemons, and now manufactured synthetically is also used in degreasing liquids. The Envirowise guide explains the advantages and disadvantages of biological cleaners.
Conversion coating
Many metal surfaces require treatment with a conversion coating to increase the corrosion resistance of the surface such as phosphating sand chromating. The Envirowise guide describes the savings that can be made through minimising wastes.
Combined cleaning and coating.
Some systems use a batch multi-stage cabinet spray unit - rather like a large dishwasher - to clean parts using a neutral or alkaline solution, followed by phosphating and rinsing. The need for VOC-based degreasers is therefore eliminated. The Envirowise guide explains the benefits of these combined systems.
Download the Alternative Supplier List opposite.