Solvent sinks commonly known as "parts washers" are appropriate for a print shop for the parts of the press that can be placed in it to be cleaned. Solvent is supplied typically from a 30-gallon barrel and is re-circulated. The solvent may be filtered in the sink and used until it is dirty and no longer effective. Solvent sinks can be purchased and maintained by the printer or may be leased from a service company. If leased, the solvent sink is generally serviced by the equipment provider company that will remove and replace ineffective solvent on a regular schedule. Service companies typically use recycled solvent for solvent sinks. The service company must be a licensed supplier and solvent recycler.
The benefits of a solvent sink include a reduction in the use of fresh solvent and improved worker safety because there is less handling of solvent-soaked shop towels to clean press parts. Justification of the solvent sink can be made with the savings associated with reducing the use of shop towels and solvents, as well as waste in disposal costs. In specifying the parts washer, it should be large enough to contain the appropriate parts, such as ink trays.
Best Management Practices & Pollution Prevention
- Purchase or lease a parts washer with an integral filtration unit.
- Use solvents that are compliant with current state regulations. Many states now regulate parts washers as a cold solvent cleaner and have set a vapor pressure limit 1.0 mm Hg at 68°F.
- Use solvents that have a flashpoint above 100°F to avoid OSHA regulations and ideally above 140°F to help avoid EPA hazardous waste regulations.
- If a service is not going to be used for the solvent and a specific rule does not apply, use one that is either compatible or identical to the press cleaning solvent so that the used press solvent can be used in the unit prior to recovery or disposal.
- Used solvent can be recycled on site with addition of a solvent distillation unit. This unit will significantly reduce the amount of hazardous waste to the still bottom that has to be disposed of as a hazardous waste.
- Solvent should only be replaced when necessary. Service provider schedules may need to be adjusted according to in-plant usage.
- Lids should be kept closed when not in use to reduce solvent evaporation, which leads to fugitive VOC emissions.
- Consider using a water-based cleaning solution parts washer.
For access to vendors who may supply alternative materials and equipment, see the PNEAC Vendor Directory.
The solvent used in parts washers is commonly naphtha or other similar solvent blend. Alternative, low vapor pressure solvents are commonly a source of VOC emissions and should not be passed over when considering emission calculations and reporting.
The emissions from the solvent parts washer should be measured through a mass balance formula. Records of the amount of solvent provided by the parts washer service provider should be maintained. The amount of solvent disposed of should be compared to the amount of new solvent provided during the previous delivery in order to measure the evaporative loss. If make-up solvent is added to the tank, records of the amount of solvent added each time should be maintained. These records should be compared to the previous amount of solvent added to calculate the evaporative losses.
Typically, the waste solvent from solvent parts washers is classified as a hazardous waste due to the flashpoint of the solvent. This waste stream should be considered when calculating the facilities waste generator status.
The hazardous waste solvent containers must be properly labeled with the EPA Hazardous Waste labels and must be manifested according to state and federal environmental regulations. The containers also must be labeled with the appropriate DOT labels (i.e., flammable warnings) and the transporter must have all appropriate DOT placards in place.
Health & Safety
Chemical appropriate gloves, apron and eye protection should be worn when using a parts washing unit.
Ample air ventilation should be provided.
The equipment should be properly grounded to reduce the risk of fire, if the flashpoint of the solvent being used is less than 100°F.