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THE ENVIRONMENTAL TECHNOLOGY VERIFICATION 

PROGRAM 

ETV Joint Verification Statement 

TECHNOLOGY TYPE: BAGHOUSE FILTRATION PRODUCTS 

APPLICATION: CONTROL OF PM2.5 EMISSIONS BY BAGHOUSE 

FILTRATION PRODUCTS 

TECHNOLOGY NAME: L3650 

COMPANY: W. L. Gore & Associates, Inc. 

ADDRESS: 101 Lewisville Road 

P.O. ox 1100 

Elkton, MD 21022 

PHONE:

FAX: 

(410) 392-3300 

(410) 398-6624 

WEB SITE: http://www.gore.com

E-MAIL: cpolizzi@wlgore.com

The U.S. Environmental Protection Agency (EPA) has created the Environmental Technology 

Verification (ETV) Program to facilitate the deployment of innovative or improved environmental 

technologies through performance verification and dissemination of information. The goal of the ETV 

Program is to further environmental protection by accelerating the acceptance and use of improved and 

cost-effective technologies. ETV seeks to achieve this goal by providing high-quality, peer-reviewed data 

on technology performance to those involved in the design, distribution, financing, permitting, purchase, 

and use of environmental technologies. 

ETV works in partnership with recognized standards and testing organizations; stakeholder groups, which 

consist of buyers, vendor organizations, permitters, and other interested parties; and with the full 

participation of individual technology developers. The program evaluates the performance of innovative 

technologies by developing test plans that are responsive to the needs of stakeholders, conducting field or 

laboratory tests (as appropriate), collecting and analyzing data, and preparing peer-reviewed reports. All 

evaluations are conducted in accordance with rigorous quality assurance protocols to ensure that data of 

known and adequate quality are generated and that the results are defensible. 

The Air Pollution Control Technology (APCT) Verification Center is operated by RTI International 

(RTI), in cooperation with EPA’s National Risk Management Research Laboratory. The APCT 

Verification Center evaluates the performance of baghouse filtration products (BFPs) used primarily to 

U.S. Environmental Protection Agency 

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control PM2.5 emissions (particles 2.5 μm and smaller in aerodynamic diameter). This verification 

statement summarizes the test results for W. L. Gore & Associates, Inc.’s filter fabric L3650. 

VERIFICATION TEST DESCRIPTION 

All tests were performed in accordance with the APCT Generic Verification Protocol for Baghouse 

Filtration Products, available at http://etv.rti.org/apct/pdf/baghouseprotocol.pdf. The protocol is based on 

and describes modifications to the equipment and procedures described in Verein Deutscher Ingenieure 

(VDI 3926, Part 2), Testing of Filter Media for Cleanable Filters under Operational Conditions, 

December 1994. The VDI document is available from Beuth Verlag GmbH, 10772 Berlin, Germany. 

The protocol also includes requirements for quality management, quality assurance, procedures for 

product selection, auditing of the test laboratories, and test reporting format. 

Outlet particle concentrations from a test fabric were measured with an impactor equipped with 

appropriate substrates to filter and measure PM2.5 within the dust flow. Outlet particle concentrations 

were determined by weighing the mass increase of dust collected in each impactor filter stage and 

dividing by the gas volumetric flow through the impactor. 

Particle size was measured while injecting the test dust into the air upstream of the baghouse filter 

sample. The test dust was dispersed into the flow using a brush-type dust feeder. The particle size 

distributions in the air were determined both upstream and downstream of the test filter fabric to provide 

accurate results for penetration through the test filter of PM2.5. All tests were performed using a constant 

18.4 ± 3.6 g/dscm (8.0 ± 1.6 gr/dscf) loading rate, a 120 ± 6.0 m/h (6.6 ± 0.3 fpm) filtration velocity 

[identical to gas-to-cloth ratio (G/C*)], and aluminum oxide test dust with a measured mass mean 

aerodynamic diameter maximum of 1.5 μm (average of three impactor runs). All baghouse filtration 

products are tested in their initial (i.e., clean) condition. 

Each of the three test runs consisted of the following segments: 

• Conditioning period – 10,000 rapid-pulse cleaning cycles, 

• Recovery period – 30 normal-pulse cleaning cycles,

• Performance test period – 6-hour filter fabric test period with impactor. 

VERIFIED TECHNOLOGY DESCRIPTION 

The W. L. Gore & Associates, Inc. company provided the following information about their product. The 

L3650 is a GORE membrane/fiberglass fabric laminate with a weight of 22 oz/yd2

 (746 g/m2). 

Figure 1 is a photograph of the fabric. Sample material was received as nine 46 x 91 cm (18 x 36 in.) 

swatches marked with the manufacturer’s model number, year, and month of manufacture, and cake side. 

Three of the swatches were selected at random for preparing three test specimens 150 mm (5.9 in.) in 

diameter. 

VERIFICATION OF PERFORMANCE 

Verification testing of the W. L. Gore & Associates, Inc., L3650 filter fabric was performed during 

October 18–25, 2005, for standard test conditions at the test facility of ETS, Incorporated, 1401 

Municipal Road, Roanoke, VA 24012. Test conditions are listed in Table 1. The overall test results 

summarized in Table 2 are the averages of three individual tests. 

____________ 

*Filtration velocity and gas-to-cloth ratio are used interchangeably and are defined as the gas flow rate divided by 

the surface area of the cloth. 

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Figure 1. Photograph of W. L. Gore & Associates, Inc.’s L3650 filter fabric

Table 1. Test Conditions for Baghouse Filtration Products Brand/Model: 

W. L. Gore & Associates, Inc.’s L3650 

Test parameter Value

Dust concentration 18.4 ± 3.6 g/dscm (8.0 ± 1.6 gr/dscf) 

Filtration velocity (G/C) 120 ± 6 m/h (6.6 ± 0.3 fpm) 

Pressure loss before cleaning 1,000 ± 12 Pa (4 ± 0.05 in. w.g.) 

Tank pressure 0.5 ± 0.03 MPa (75 + 5 psi) 

Valve opening time 50 ± 5 ms 

Air temperature 25 + 2 oC (78 + 4 oF) 

Relative humidity 50 ± 10 % 

Total raw gas stream flow rate 5.8 ± 0.3 m3/h (3.4 ± 0.2 cfm) 

Sample gas stream flow rate 1.13 ± 0.06 m3/h (0.67 ± 0.03 cfm) 

Number of filtration cycles 

• During conditioning period 10,000 cycles 

• During recovery period 30 cycles 

Performance test duration 6 h ± 1 s 

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Table 2. Baghouse Filtration Product Three-run Average Test 

Results for W. L. Gore & Associates, Inc.’s Fabric L3650 

Verification parameter At verification test 

conditions 

Outlet particle concentration at standard conditionsa

 PM2.5, g/dscm 

 (gr/dscf) 

 Total mass, g/dscmb

 (gr/dscf) 

<0.000002 

(<0.000007) 

<0.000002 

(<0.000007) 

Average residual pressure drop, cm w.g. (in. w.g.) 2.45 (0.96) 

Initial residual pressure drop, cm w.g. (in. w.g.) 2.36 (0.93) 

Residual pressure drop increase, cm w.g. (in. w.g.) 0.18 (0.07) 

Filtration cycle time, s 251 

Mass gain of test sample filter, g (gr) 0.09 (1.39) 

Number of cleaning cycles 87 

NA = Not applicable – values shown are for three tests. 

a

 Standard conditions: 101.3 kPa (14.7 psia) and 20 °C (68 °F). One or more of the impactor substrate weight 

changes for these results were near the reproducibility of the balance. 

b

 Total mass includes the mass of PM2.5 and larger particles that passed through the fabric. 

The APCT Verification Center quality assurance officer has reviewed the test results and the quality 

control data and has concluded that the data quality objectives given in the generic verification protocol 

and test/QA plan have been attained. 

This verification statement addresses five aspects of filter fabric performance: filter outlet PM2.5

concentration, filter outlet total mass concentration, pressure drop ()P), filtration cycle time, and mass 

gain on the filter fabric. Users may wish to consider other performance parameters such as temperature, 

service life, and cost when selecting a filter fabric for their application. 

In accordance with the generic verification protocol, this verification statement is applicable to filter 

media manufactured between the signature date of the verification statement and 3 years thereafter. 

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Signed by Sally Gutierrez 7/28/06 Signed by Andrew R. Trenholm 7/20/06

Sally Gutierrez Date Andrew R. Trenholm Date 

Director Director 

National Risk Management Research Laboratory APCT Verification Center 

Office of Research and Development RTI International 

United States Environmental Protection Agency 

NOTICE: ETV verifications are based on an evaluation of technology performance under specific, predetermined 

criteria and the appropriate quality assurance procedures. EPA and RTI make no express or implied warranties as to 

the performance of the technology and do not certify that a technology will always operate as verified. The end user 

is solely responsible for complying with any and all applicable federal, state, and local requirements. Mention of 

commercial product names does not imply endorsement. 

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