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Forensic
Engineers -
VOSI Research Report RR9-V41
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"EVALUATION OF
VOSI & ASTM TASK GROUP FRICTION TEST SENSORS"
REFERENCES:
- VOSI V41.21, "Universal Specification/Test Method
for Slip Resistant Walkways, in the Field &
Laboratory, as Measured by a Drag Type Friction
Tester".
- "Board of Directors Task Group on Slip
Resistance"; Report to ASTM F13 committee members
from Dave Fleisher, 12/22/00
- "Interview with the Chairman of the 2001 ASTM Board
of Directors - Donald E. Marlowe"; ASTM
"Standardization News", January 2001
- "ASTM Lights the Way for Tissue Engineered Medical
Products Standards" by Grace Lee Picciolo, PhD &
David L. Stocum; ASTM "Standardization News",
January 2001
Ref. 1 specifies that both leather and Monarch EVA sensors
are used dry and Monarch EVA wet (distilled water) when
measuring walkway slip resistance regardless of flooring
material or coatings.
Ref. 2 specifies leather, Neolite and Toplift TPU
(Thermoplastic polyurethane) as surrogate footwear materials
for testing walkways.
The purpose of the 1/19/2001 research was to test both VOSI
test materials, rubber and leather, and compare them with the
ASTM task group test materials. Using the Technical Products
Co. Model 80 Floor & Footwear Friction Tester and the ASTM
C1028 calibration ceramic tile, wet and dry testing was
performed on all elastomers, while only dry testing was
performed on the leather.
A 4" x 4" x 1/4" thick sample of
"Toplift TPU" ,the same sample used for ASTM testing
which was supplied to Wen Chung of Liberty Mutual Insurance
Co., was obtained from Dave Kincman, owner of Styletek,
manufacturer of the "Toplift TPU".
The measured Shore D hardness of the three samples received
was 56-62. The samples are patterned on one side and smooth on
the other side. Three plugs, 7/16" diameter were cut for
the Model 80 (smooth side out). All samples were sanded with
400-grit wet/dry paper before dry testing and were not
re-sanded for wet test. The Monarch EVA values were corrected
to "standard rubber" dry and wet values marked on
the back of the Technical Products Co. primary standard #7
ceramic tile. Separate 10 lb. Model 80 test blocks were used
to contain each of the four materials tested, with the
following results:
Table 1.
|
|
SCOF DRY/C1028 Tile |
|
SCOF WET/C1028 Tile |
|
Sensor Material |
Avg. |
+ |
- |
S.D. |
|
Avg. |
+ |
- |
S.D. |
|
Neolite |
0.62 |
0.02 |
0.04 |
0.021 |
0.05 |
0.02 |
0.02 |
0.014 |
|
Monarch EVA (uncorrected) |
0.44 |
0.02 |
0.00 |
0.007 |
0.36 |
0.01 |
0.02 |
0.011 |
|
Monarch EVA (corrected) |
0.50 |
0.02 |
0.00 |
0.007 |
0.35 |
0.01 |
0.02 |
0.011 |
|
Leather |
0.27 |
0.01 |
0.02 |
0.011 |
Can't wet test leather |
|
TPU, before sanding |
0.25 |
0.01 |
0.01 |
0.007 |
- |
- |
- |
- |
|
TPU, after sanding |
0.26 |
0.01 |
0.01 |
0.007 |
0.33 |
0.01 |
0.02 |
0.011 |
Test Conditions:
67oF, 50% relative humidity. Gage Correction Factor and Humidity
Correction Factor = 1.00
Ref. 3 states: "Donald E. Marlowe is the director of
the Office of Science & Technology at the Center for
Devices & Radiological Health of the Food & Drug
Administration (FDA)" .
Mr. Marlowe's comment on the following interviewer's
question: "The National Technology Transfer Act of 1995
requires that all federal agencies utilize private sector
standards. How has FDA responded to the NTTAA since its
implementation?" was "...our whole program relating to standards,
dating back to the late 1970s, has been based on the premise
of using consensus standards to describe how devices should
perform." Mr. Marlowe also states: "The Tech
Transfer Act enabled us to strengthen the message we were
trying to convey to the medical device manufacturers about the
inherent benefits of developing PERFORMANCE standards through
the consensus process."
The word "performance" is emphasized because all
of the present ASTM "standards" for measuring slip
resistance of flooring and footwear are actually test methods
for using specific test instruments for measuring both the
SCOF of flooring materials and coatings or measuring both the
SCOF and DCOF of footwear materials.
VOSI is the only NIST recognized private sector standards
development organization that has approved performance based
consensus standards for measuring the SCOF of both walkway
materials and coatings (ref. 1) and footwear (VOSI V41,22).
(see www.voicesofsafety.com
..."About VOSI" and "Slip & Fall
Standards").
The only performance based ASTM test method for measuring
the SCOF of polishes is ASTM D2047. This test method uses a
leather sensor and the non-portable James Machine. The typical
substrate for testing polishes is "Official Vinyl
Composition Tile" (OVCT).
Ref. 4 states: "Uniformity in regulatory review and
approvals will be improved and expedited, as the opportunity
for standards recognition by the FDA and self certification by
the manufacturer are provided" (D. E. Marlowe, et al.,
1998 "FDA Recognition of Consensus Standards in the
Pre-market Notification Program", Biomedical
Instrumentation & Technology, Hanley & Belfus, Inc. pp.
301-304).
VOSI requires that operators of drag type SCOF testers be
certified in order that test results be accurate.
Conclusions:
- Neither Neolite nor Toplift TPU represents rubber
footwear soling materials, whereas Monarch EVA was
selected because it represents an average rubber footwear
soling material.
- All sensor material s used for measuring the SCOF of
flooring or coatings have variable properties due to lot
and sanding variations. Since SCOF involves the properties
of both the sensor and floor or coating, the sensor must
be standardized in order that the floor or coating is the
only variable.
- Donald Marlowe, Chairman of the ASTM Board of Directors
and Slip Resistance Task Group Chairman should review the
performance based VOSI standards and reference these
documents in all ASTM test methods for measuring SCOF or
DCOF.
- See www.voicesofsafety.com
...read "About VOSI" ...Click on "Slip
& Fall Standards" and "Public
Safety"
- Research should not be performed in a vacuum. All
pertinent documents should be reviewed in order not to
waste time on useless research.
Donald C. Meserlian, P.E.
VOSI Chairman & ASTM Member
F 13, D21C21F6 etc.