Questions and Answers on Alternative Solvents
This fact sheet provides an overview of regulations governing production, use and replacement of three ozone-depleting solvents, CFC-113, methyl chloroform (1,1,1-trichloroethane, TCA or 1,1,1), and HCFC-141b (1,1-dichloro-1-fluoroethane), under Title VI of the Clean Air Act. This fact sheet also provides information on how to find substitutes. If you have questions beyond those in this fact sheet, or would like paper copies of the lists, please call the Stratospheric Ozone Protection Hotline toll-free at 1 (800) 296-1996.
Questions and Answers about EPA's SNAP Program and the Use of Cleaning Solvents CFC-113, TCA, HCFC-141b and their Substitutes
A. SNAP review process
- What does "SNAP" stand for and what is involved in SNAP program reviews?
- Where can I find information on which substitutes have been listed as acceptable or unacceptable under SNAP?
- I want to get SNAP approval for a compound or a process used as a cleaning solvent. What should I do?
B. Scope of SNAP
- Which solvent uses are subject to SNAP review and requirements?
- What do you mean by “Non-aerosol solvent cleaning”?
C. SNAP Status of Different Substitutes
- Which substitutes for CFC-113, TCA or HCFC-141b have already been listed as acceptable under the SNAP program?
- What’s going on with the SNAP review of nPB?
A. SNAP review process
What does "SNAP" stand for and
what is involved in SNAP program reviews?
SNAP is EPA's Significant New Alternatives
Policy program. The SNAP program implements Section 612
of the Clean Air Act. Under SNAP, EPA evaluates
substitutes that companies propose to use as
replacements for ozone-depleting substances like
CFC-113, TCA, and HCFC-141b, in order to determine that
the substitutes won't cause greater damage overall to
human health or the environment than either the ozone
depleters they are replacing or than other available
substitutes. EPA generally reviews four key items when
evaluating each proposed substitute:
- ozone-depleting potential,
- global-warming potential,
- toxicity, and
- Based on this evaluation, EPA then decides whether unrestricted use of a substitute should be allowed, certain limits need to be placed on use, or use should be prohibited altogether.
- Where can I find information on which substitutes have been listed as acceptable or unacceptable under SNAP? EPA published its first set of SNAP decisions on March 18, 1994 in the Federal Register (59 FR 13044). Since then, EPA has issued numerous updates. You can view the lists at www.epa.gov/ozone/snap/lists/.
I want to get SNAP approval
for a compound or a process used as a cleaning solvent.
What should I do?
- You should first determine if the specific application you have in mind falls within the scope of the industrial sectors that are subject to SNAP. Your proposal may involve a compound that does not substitute for an ozone-depleter, or an application where ozone depleters have played only a minor role. In these cases, SNAP may not apply.
- Next, if you think that SNAP applies, you should check the lists of substitutes under SNAP for the appropriate sector. If your substitute is already on an existing list for acceptable, acceptable-with-restrictions, or unacceptable substitutes, EPA does not require further review. Please be aware that in the cleaning solvents sector, EPA does not certify individual companies' products. Instead, the acceptability decisions are for specific compounds (e.g., trichloroethylene), for classes of substitute compounds (e.g., oxygenated organic solvents), or for processes (e.g., no-clean).
- If your substitute is not on a list or if you are not sure if SNAP applies, you should call the SNAP solvents sector analyst at 202-343-9210 to determine whether your product is covered by a broad category or has otherwise been addressed by the SNAP program.
- If you and the analyst together decide that your product is new and has not been reviewed, you must submit it for EPA review using the SNAP submission form. You can get the form by calling the hotline or viewing http://www.epa.gov/ozone/snap/submit/index.html.
B. Scope of SNAP
Which solvent uses are subject
to SNAP review and requirements?
EPA currently reviews substitutes for CFC-113,
TCA and HCFC-141b as a solvent in three industrial
- non-aerosol solvent cleaning,
- aerosols (aerosol solvents), and
- carrier solvents used in adhesives, coatings and inks, because it was in these sectors that use of CFC-113 and TCA were most widespread. EPA chose not to subject to SNAP review industrial sectors that historically used CFC-113, TCA and HCFC-141b on a more limited basis, such as hydraulic system testing.
What do you mean by
“Non-aerosol solvent cleaning”?
In this sector, EPA has historically applied
SNAP only to large industrial cleaning applications,
including cold cleaning and vapor degreasing and
defluxing. Typically, these involve a bath of solvent.
SNAP categorizes industrial cleaning as either:
- precision cleaning,
- electronics cleaning, or
- metals cleaning.
As clarified in a SNAP Notice published on February 28, 1998 (63 FR 9151), the three end-uses are defined as follows:
Metals cleaning: The removal of a wide variety of contaminants from metal objects during a manufacturing or maintenance process. At each stage in the process, contaminants must be removed from the piece to ensure a clean metal surface for the next step in the production process or for final consumption. These parts tend to be metal objects ranging from fully assembled aircraft down to small metal parts stamped out in high volume. These contaminants are most often greases, cutting oils, coatings, large particles, and metal chips.
Electronics cleaning: Primarily the removal of flux residues from wiring assemblies on printed circuit boards after a soldering operation has been completed. This is considered a high-value end-use where performance is critical.
Precision cleaning: This term applies to the cleaning of any components or surfaces of any composition for which an extremely high level of cleanliness is necessary to ensure satisfactory performance during the manufacturing process or in final consumption. This end-use is characterized as very high value based on non-cost criteria, including high value products, protection or safeguarding of human life, compatibility concerns with plastics, temperature and mechanical stress limitations, precision mechanical assemblies/ components with demanding machining tolerances or complex geometries, and base or mix of metals readily pitted, corroded, eroded or otherwise compromised.
Examples of “high-performance electronics and precision cleaning” include cleaning of high-value added parts for aerospace, military, or medical applications such as precision ball bearings for navigational devices, automotive safety circuits (e.g., airbag deployment and braking systems), or medical devices.Non-aerosol solvent cleaning applications that EPA has chosen not to subject to SNAP include:
- bearer media (e.g., a substitute for CFC-113 or HCFC-141b in depositing lubricants on medical catheters)
- plasma etching
- mold release agents for non-aerosol applications
- motor vehicle air conditioning (MVAC) flushing
- hand wiping, hand cleaning, and maintenance cleaning as a non-aerosol
- dry cleaning of textiles
- substitutes for CFC-11
- flushing of oxygen systems
If EPA determines in the future that the use of ozone depleters or their substitutes in any of these applications poses a significant environmental or health risk, EPA could begin requiring SNAP review and requirements for solvents used in these applications.
C. SNAP Status of Different Substitutes
Which substitutes for CFC-113,
TCA or HCFC-141b have already been listed as acceptable
under the SNAP program?
EPA has already listed as acceptable many
non-aerosol solvent cleaning substitutes for CFC-113
and TCA, including:
- Aqueous cleaners
- Semi-aqueous cleaning processes containing solvents already acceptable under SNAP
- Non-ozone-depleting chlorinated solvents (methylene chloride (MeCl), trichloroethylene, perchloroethylene)
- Organic solvents used without water (terpenes, petroleum hydrocarbons, and oxygenated organic solvents such as esters, ethers, alcohols, etc.)
- Volatile methyl siloxanes
- No-clean processes such as those used in manufacturing printed circuit boards
- Various hi-tech processes such as supercritical fluid cleaning, UV-ozone cleaning, plasma cleaning.
- Hydrofluoroether (HFE) 7100 and 7200 (also acceptable as an aerosol solvent and a carrier solvent in adhesives, coatings, and inks)
- Monochlorotoluenes and benzotrifluorides, subject to a 50 ppm workplace standard for monochloro-toluenes and a 100 ppm standard for benzotrifluoride (also acceptable as aerosol solvents and as substitutes for CFC-113 and TCA in adhesives, coatings and inks). This includes parachlorobenzotrifluoride (PCBTF).
- HFC-4310mee, subject to a 200 ppm time-weighted average workplace exposure standard and 400 ppm workplace exposure ceiling (also acceptable as substitutes for HCFC-141b.
- HFC-365mfc (also acceptable as a substitutes for HCFC-141b)
- HCFC-123 (for precision cleaning only)
- Perfluorocarbons (PFCs) and perfluoropolyethers (PFPEs), although they are only acceptable for high-performance, precision-engineered applications in which reasonable efforts have been made to ascertain that other alternatives are not technically feasible due to performance or safety requirements.
- Heptafluorocyclopentane (HFCPA).
- HCFC-141b, and
- chlorobromomethane (CBM).
What’s going on with the SNAP review of
EPA has received petitions to add n-propyl
bromide (nPB) to the list of
acceptable alternatives for the CFC-113, TCA and
HCFC-141b in the
solvent sector for metal, precision, and
electronics cleaning, as well
as in aerosol and adhesive applications.
EPA issued a proposed rule on June 3, 2003 . EPA is proposing to list n-propyl bromide (nPB) as an acceptable substitute for ozone-depleting substances (ODSs), subject to use conditions, in the solvent cleaning sector and aerosol solvents and adhesive end uses. While we find that nPB has a short atmospheric lifetime and low ozone depletion potential when emitted from locations in the continental U.S., the Agency cautions that significant use of nPB closer to the equator poses significant risks to the stratospheric ozone layer. Further, if workplace exposure to nPB is poorly controlled, it may increase health risks to workers. In the interim, until the Occupational Safety and Health Administration (OSHA) develops a mandatory workplace exposure limit under the Occupational Safety and Health Act, the Agency recommends that users of nPB adhere to an acceptable exposure limit of 25 parts per million (ppm) over an eight-hour time-weighted average.
EPA is proposing to list nPB as an acceptable substitute for chlorofluorocarbon (CFC)-113, hydrochlorofluorocarbon (HCFC)-141b, and methyl chloroform when used in aerosol solvent and adhesive end uses, subject to the condition that nPB used in these end uses not contain more than 0.05% isopropyl bromide by weight before adding stabilizers or other chemicals. We are also proposing to list nPB as an acceptable substitute for CFC-113 and methyl chloroform in general metals cleaning, electronics cleaning, and precision cleaning, subject to the condition that nPB used in these end uses not contain more than 0.05% isopropyl bromide by weight before adding stabilizers or other chemicals.
The public comment period on this proposal is from June 3, 2003 through August 4, 2003. The proposed rule gives instructions on how to submit your comments.
After considering the public comments, EPA will prepare a final rule in consultation with other parts of the government. The timing of the final rule will depend on the number and complexity of the issues raised in public comments. It usually takes EPA a year or more to finalize a rule after issuing a proposal.