Page 7 - Design Criteria.qxd

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8
Vermiculite’s thin, flexible, soft plates can be
exfoliated like graphite. They retain the
sealability and low porosity of graphite, but
Flexitallic’s new Thermiculite sheet gaskets
will not oxidize at high temperatures.
10 100 1000 10000
100
90
80
70
60
50
40
30
20
10
0
Elapsed Time (Hours)
% Load Retention
This graph illustrates that, unlike graphite, the load loss
at operational temperatures does not increase with time.
Room Temperature Tightness (ROTT) behavior characterization
(Refer to page 41 for new method for determining factors.)
The above graphs are taken from the actual tests performed by TTRL.
Graphite @ 370°C (700°F)
Graphite @ 510°C (950°F)
Thermiculite @ 370°C (700°F)
Thermiculite @ 510°C (950°F)
250
482
300
572
350
662
400
752
450
842
500
932
550
1022
600
1112
650
1202
700
1292
750
1382
800
1472
850
1562
900
1652
0
10
20
30
40
50
60
70
80
90
100 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45
Each specimen held
successively for 3 days at
each temperature and the
change of weight recorded
WORST EXFOLIATED
GRAPHITE TESTED
BEST EXFOLIATED
GRAPHITE TESTED
Temperature °C
Temperature °F
Cumulative Weight Loss (%)
Time Since Start of Test (days)
200
392
Cumulative Iso-thermal weight loss results for the best and
worst exfoliated graphite tested
Thermiculite™
THERMICULITE
SHEET MATERIAL
1 10 100 1000 10000 100000 1000000
100000
100
10000
1000
Gasket Stress, Sg (psi)
a = 0.200
Gb = 1,906
Filled Markers - 400 psi
Unfilled Markers - 800 psi
FL28RT01
FL28RT03
Gs = 456
Part B1
Part B2
Part B3
Part A
Gb a Gs T PMIN TPMAX
1,906 0.2 456 18 58,645
Tightness Parameter, Tp
S 100 S 1000 S 3000 S 10000
4,788 7,588 9,400 12,026