| Overview: |
A vacuum sanding system is essentially a dry abrasive blasting
process (e.g., sand, steel, or plastic media blasting) with a vacuum
system attached to the blast head to collect the blast media and the
removed coating material (paint or rust). The unit then separates the used
blast media from the removed coating material. The remaining blast
material is recycled for further use and the coating material is
disposed. This system is designed to replace chemical paint
stripping, and has three added advantages. The first advantage is the
collection of both the blasting media [e.g., sand, plastic media blast
(PMB) or other media] and the collection of the waste coating material
being removed. The second advantage is that the media is separated from
the waste material by a reverse pulse filter. The media is reused in the
system, thereby minimizing the quantity of medium required. The third
advantage is that, due to the confinement of the blast material, this
technology may be used where it is impractical to use traditional
sandblasting or chemical stripping. This system is a stand-alone
system, including the air compressor to drive the system. It is portable
(skid mounted) and can be moved by a forklift. The air compressor is a
trailer unit (2-wheeled). If PMB is used as the media in the vacuum
sanding system, the used media can be passed through a reclamation system
that consists of a cyclone centrifuge, a dual adjustable air wash,
multiple vibrating classifier screen decks, and a magnetic separator. In
addition, some manufacturers provide dense particle separators as a
reclamation system. The denser particles, such as paint chips, are
separated from the reusable blast media, and the reusable media is
returned to the blast pot. Typically, media can be recycled ten to twelve
times before it becomes too small to remove paint effectively. Waste
material consists of blasting media and paint chips. The waste material
may be classified as a RCRA hazardous waste because of the presence of
metals. An alternative solution to handling a potential hazardous waste is
to locate a vendor that would "lease" the blast media to the base and then
recycle the media to recapture the metals. (See P2 Opportunity Handbook Data Sheet: Plastic Media Blasting
[PMB] Paint Stripping.) The effect this technology has on
pollution prevention is that the portable vacuum sander removes coatings
and corrosion from composite or metal structures while capturing the media
and solid waste. Vacuum sanding may eliminate airborne particulate matter
and potential hazardous lead dust exposure. When compared to chemical
paint stripping, this technology eliminates the generation of waste
solvent. Vacuum sanding has been used at NAVSTA Everett located in
Everett, Washington. The original application of this technology was to
remove paint on asphalt as well as for maintenance of large service
pipelines leading to NAVSTA Everett. When NAVSTA Everett de-paints
pipelines on naval piers, the U.S. EPA requires complete recovery of waste
materials, making both traditional sand or water blasting and chemical
stripping impractical. This is an abrasive blasting process and not
associated with traditional sanding using an abrasive paper. This system
has potential applications for paint removal on buildings/facilities and
structures within the Air Force. It has only very limited application for
paint removal on aircraft when used with plastic media. This system would
be effective for accomplishing selective area paint removal where
paint-stripping facilities are not available. The system would also work
well to supplement other stripping methods, as an example to remove paint
from areas that were masked during paint removal.
|
| Compliance Benefit: |
Use of a vacuum
sanding system will help a facility decrease the amount of stripping
chemicals used and stored on site, thereby decreasing the possibility
that the facility will meet reporting thresholds for those chemicals under
SARA Title III (40 CFR 300, 355, 370, and 372) as well as Executive
Order (EO) 13148. In addition, less hazardous waste is
generated in vacuum sanding compared to traditional sandblasting or
chemical stripping since solvents are eliminated and the blast media can be
reused. The decrease in hazardous waste helps facilities to meet the requirements
of waste reduction under RCRA, 40 CFR 262; the Pollution Prevention Act
(42 USC 13101-13109); and EO 13148; and may also help facilities to
reduce their generator status and regulatory burden under RCRA, 40 CFR
262 (i.e., record-keeping, reporting, inspections, transportation,
accumulation time, emergency prevention and preparedness, emergency
response). Moreover, the vacuum sanding system decreases a facility’s need
to obtain an air permit under 40 CFR 70 and 71. Eliminating VOC emissions
associated with solvent cleaning may also help a facility to comply with or
avoid the requirements of the National Emission Standards for Hazardous Air
Pollutants (NESHAPs) (40 CFR 63).
The compliance benefits listed here are only meant to be used as general
guidelines and are not meant to be strictly interpreted. Actual compliance
benefits will vary depending on the factors involved, e.g., the amount of
workload involved.
|
| Materials Compatibility: |
Storage and
handling of sand or plastic media and blast waste associated with this
process pose no compatibility problems. Collection systems should not mix
different types of waste (i.e., pipeline paint and paint from asphalt) to
ensure the most economic disposal can be obtained for each. Prior to using
plastic media for de-painting operations, personnel should check
applicable military specifications [such as (MIL-P-85891)] and operations
manuals for the PMB systems. Some military specifications do not allow PMB
for de-painting certain types of materials (i.e., fiberglass, certain
composites, honeycomb sandwich structures, and some applications with
thin-skinned aircraft components). In certain cases, PMB can inhibit crack
detection on some of the softer alloys used for aircraft components (e.g.,
magnesium).
|
| Safety and Health: |
Airborne dust, which
is a major safety and health concern with any blasting operations, may be
eliminated using the vacuum blasting system. In order for the vacuum
system to be effective, the vacuum and blasting head must be kept in
contact with the material being stripped of paint or corrosion. Therefore,
training in the proper use of the equipment is essential. In addition, eye
protection and hearing protection are recommended.Consult your
local industrial health specialist, your local health and safety
personnel, and the appropriate MSDS prior to implementing this
technology.
|
| Benefits: |
- Improves personnel
safety since it eliminates airborne particulate matter and potential lead dust
exposure hazard.
- May eliminate the
need for the use of respirators while blasting.
- Separates waste
material from blasting media, therefore, the media can be
recycled.
- Vacuum sanders are
versatile and can use multiple media types.
- Wastewater
disposal costs (typical in chemical paint stripping operations) are
virtually eliminated with vacuum sanding.
- Eliminates the
production of waste solvents when compared to chemical paint
stripping.
- Unit is portable
and contains a self-supplied power/air compressor.
- Minimal emissions
from portable (mobile source) diesel air compressors, so no air permit
required.
- Minimizes the
clean up time since blast material is contained.
- Other activities
can continue nearby without interruptions.
|
| Disadvantages: |
- Substantial
capital equipment investment is required.
- Used blasting
materials and waste coating material may have to be disposed as a
hazardous waste.
- Operator training
is critical to success and safety of operation.
- Operator time,
maintenance requirements, handling, and disposal of waste varies upon
material to be stripped.
- Quality of
stripping is dependent on skill and experience level of the
operator.
|
| Economic Analysis: |
Vacuum sanding systems can range in cost from $17,000 to $40,000,
excluding the portable generator to operate the system. The following
information on investment costs and costs/payback for a vacuum sanding
system at NAVSTA Everett, Washington was published in the Arthur D.
Little Report Site Assessment Pollution Prevention Equipment at NAS North
Island SUBASE, Bangor, NAVSTA Pascagoula, and NAVSTA Everett, August
1995.
The following analysis compares a vacuum system to a
traditional sand blasting system (although the sand blasting system may
not be able to be used based on EPA constraints described in the
overview).
Assumptions:
- Labor rate: Vacuum
Sanding (VS) and Traditional Sandblasting (TS) - $45/hr.
- Work load: VS and
TS - 7200 square feet de-painted/yr.
- Rate of
de-painting: VS and TS - 4 square ft/min.
- Total hours per
year including setup/operation/cleanup: VS - 40 hrs/yr; TS - 80
hr/yr.
- Materials: VS -
plastic media rental cost $2.50/lb, includes disposal of waste
segregated from media x 1,500 lbs/yr = $3,750/yr; TS - material cost
$1.50/lb x 1,500 lb = $2,250/yr.
- Disposal: VS - $0;
TS - $.60/lb x 15,000 lb + $36/drum x 25 drums = $9,900.
- Utilities: VS and
TS - Diesel fuel $1.00/gallon x 60 gallons/yr = $60.
- Equipment
maintenance: VS - $2,200; TS - $700.
Table 1. Annual Operating Cost Comparison for Vacuum Sanding versus
Sandblasting
| |
Vacuum Sanding |
Sandblasting |
|
Operational
Costs: |
|
|
|
Labor:
|
$1,800
|
$3,600
|
|
Material: |
$3,750
|
$2,250
|
|
Energy:
|
$60
|
$60
|
|
Waste
Disposal: |
$0
|
$9,900
|
|
System
Maintenance: |
$2,200
|
$700
|
|
Total
Operational Costs: |
$7,810
|
$16,510
|
|
Total Recovered
Income: |
$0
|
$0
|
|
Net Annual
Cost/Benefit: |
-$7,810
|
-$16,510
|
Economic Analysis
Summary:
- Annual Savings for
Vacuum Sanding: $8,700
- Capital Cost for Diversion Equipment/Process:
$64,000
- Payback Period for Investment in Equipment/Process: < 8
years
Click
here to View an Active Spreadsheet for this Economic Analysis and
Enter Your Own Values. To return from the Active Spreadsheet, click the
Back arrow in the Tool Bar.
|
| NSN/MSDS: |
None
identified.
|
| Approving Authority: |
Appropriate authority for making
process changes should always be sought and obtained prior to procuring or
implementing any of the technologies identified herein.
For Air Force
applications, vacuum sanding system paint stripping process must not be
used on any aircraft or weapon systems without the knowledge and approval
of the appropriate system manager, office(s) having engineering authority
on the specific airframe(s) and the Air Force Corrosion Prevention and
Control Office. Currently, the Air Force provides no technical
guidance on the use of this type of equipment. However, this equipment may
be employed wherever abrasive blasting technology is approved for the
coating removal process. This would not require any engineering approval
as long as the technical requirements for the blasting process such as
nozzle distance (12 to 24 inches), nozzle pressure, media type, etc., are
met. Note: it would probably require some significant design change to
have a vacuum head to support the nozzle distance and this would be very
unwieldy for use on aerospace equipment.
|
| Points of Contact: |
For more information
|
| Vendors: |
This is not meant to
be a complete list, as there may be other manufacturers of this type of
equipment.
Empire Abrasive Equipment Company
2101 West Cabot Blvd.
Langhorne, PA 19047-1893
Phone: (215) 752-8800
For PMB Leasing Services, See P2 Opportunity Handbook Data Sheet:
Plastic Media Blasting (PMB) Paint Stripping.
|
| Related Links: |
Do You You Remove Paint Using
Conventional Sanding Or Chemical Paintstripping? - Navy Environmental Quality Initiative (EQI)
Portable Abrasive Blast and Recovery System
|
| Sources: |
Mr. Brad Baum,
Baum & Associates, Inc., May 1996.
Ms. Chris Mahendra, Naval Air
Warfare Center, Lakehurst, NJ, May 1996.
Ms. Penny Sue Jones, Puget
Sound Naval Shipyard, February 2000.
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| Supplemental: |
Picture of
a Portable Vacuum Sanding System
|
