PRF-911 Concentric Ring
18
4. To Measure the Material under test
a. Place the specimen to be tested on the metal PTB-920 test bed.
b. Remove the PRF-911 fixture electrode protective cap and position the
fixture on the test material in the approximate center of the test bed.
c. Place the five pound PROSTAT NFPA electrode directly on top of the
PRF-911 fixture housing. Note the center electrode spring compression
and contact of the outer electrode ring with the material under test.
OPERATIONAL NOTE
The electrode assembly weighs approximately 28
ounces. The center electrode spring counters the
fixture weight with approximately 30 ounces when
fully extended. When the five pound NFPA electrode
is positioned on the fixture housing, the outer ring and
center electrodes have approximately five pounds total
pressure across both surfaces.
d. Select Test while in the Automatic Mode -- be sure no personnel are in contact
with the material or PRF-911.
Figure 11: Fixture Preparation (Continued)
Summary of Contents for PRF-911
Page 23: ......