Using and managing solvents

Reducing your solvent use can lead to a number of benefits.

Production processes

You can reduce solvent use during production processes by:

• talking to suppliers, trade associations and similar businesses about new products and processes
• pre-cleaning with non-solvent cleaners, eg line pigs, detergents, high-pressure sprays
• using sprays or other delivery systems rather than open containers when applying solvents
• sealing solvent containers with well-fitted lids, and using adhesive tape to make them airtight to minimise evaporation and contamination
• sealing containers without lids with anti-static plastic covers or stretch-wrap
• keeping solvent containers away from heat and draughts
• fitting mixing vessels and reservoirs with automatic shut-off devices or overfill alarms to avoid spills
• making sure that you contain solvent emissions wherever possible - fit a lid (even if it is partial) to degreasing or mixing vessels, and minimise emissions by using extraction systems
• using an extraction system to remove solvent emissions from closed vessels to prevent internal pressure building up
• ensuring any extraction system operates at an optimum when releases of solvent emissions are most likely, eg when vessels are open, during mixing or during production processes
• fitting alarm systems to pollution abatement equipment to alert you if there are uncontrolled emissions

You can also avoid wasting solvents by:

• pouring materials during mixing in order of volatility from lowest to highest
• using precise measuring techniques
• preparing the correct amount of materials required
• marking measurements on the container side when decanting from large containers
• avoiding splashing when filling mixing vessels and machine reservoirs
• using a funnel to reduce the risk of spills when pouring
• leaving containers open for the minimum time possible while preparing for use

Cleaning operations

Cleaning often uses more solvent than is necessary. Review your cleaning processes and consider alternative solutions, such as low-emission cleaning agents - eg citrus or water-based and vegetable-based degreasing agents.

Use the minimum amount of solvent necessary. For example, you could use a triggered spray to use less solvent and reduce operator exposure.

Introduce a 'clean as you go' policy to prevent deposits building up. If build-ups do occur, you should try to use non-solvent cleaners and a suitable scraper first to pre-clean. For difficult deposits, use a detergent with mechanical scrapers, floor scrubbers and high-pressure water jets. Fit sumps or drains with solvent interceptors and tanks which you can pump solvent out of for recovery or disposal.

If you can, use dedicated equipment so that you can avoid having to clean equipment between batches. Producing batches using similar materials or colours may help reduce cleaning.

Fully enclosed degreasing and cleaning equipment cuts evaporation and can enable you to reuse solvents. If you have to clean large vessels or tanks regularly, consider fitting automated cleaning-in-place (CIP) systems. These generally use high-pressure cleaning and can significantly reduce solvent use.

Consider pigging to clean pipelines. This involves forcing a plug or 'pig' that is normally made of rubber or steel along the pipeline. Advantages of pigging include:

• recovering expensive materials for reuse
• reducing the amount of cleaning solvent required
• potentially rapid return on investment

For more information on CIP and pigging, see our guide on how to save water at industrial premises.

Adhesives

If you use adhesives, try to find non-solvent based products. If there is no alternative to using solvent-based adhesives, you can cut solvent emissions by:

• monitoring and recording how much adhesive you are using to check you aren't using too much
• reducing evaporation by using pots with vapour traps and appropriate lids, or pots that minimise the surface area of adhesive
• storing brushes in sealed containers with cleaning solvent in the bottom
• using dosing devices to apply a controlled amount of adhesive, eg glue guns
• making sure reservoirs are properly sealed if machines are used to apply adhesive
• enclosing adhesive-application machines fully and fitting an inspection window if necessary
• pumping low-viscosity adhesives directly to the application point, glue gun or coating head