the Molten Salt Energy Technologies Web Site

filling, fluoride leakage occurred at
only 1-psi pressure. The leakage soon
stopped, and the gas flow was somewhat
retarded. When the pressure was
increased to3 psi, most of the fluoride
was forced from the container. Exami-
nation showed that only a small amount
of fluoride had adhered to the braid.
Attempts were made to run tests of
molybdenum disulfide and nickelic
oxide, but these materials were so
“fluid” that the container would not
hold them. Parts with smaller clear-
ances are being fabricated.
Face Seal Tests. Face seals are
being considered for high- temperature
use with both gases and liquids. All
tests have been run in air at room
temperature with speeds of about,
1600 rpm and pressures of up to 14 psi.
The following combinations of materials
were tested in air, without added
1 u b r i cat i on :
Carboloy (grade 779) vs. Carboloy (grade 779)
Carboloy (grade 779) VS. graphite (grade C-18)
Graphite (grade C-18) VS. graphite (grade C-18)
In the t.est of Carboloyvs. Carboloy,
a loud, grinding noise developed
within 5 min, and inspection showed
that annular grooves had been worn
into each surface. Operation with the
other two combinations of materials
was satisfactory until chattering
developed when a temperature of about
550’F was reached at the seal because
of the heat of friction. If graphite
depends upon a layer of tightly held
moisture for some of its lubrication
I -
I_._I.-. -
1150
30 1200
37 1200
- __
._ __I I__ -
PERIOD ENDING DECEMBER 10, 1952
qualities,(3 8‘) then this chattering
may be due to the driving-off of
surface-held moisture at a more rapid
rate than it can be supplied by
diffusion from the interior of the
graphite. The time required for the
test seals to reach the chattering
stage was usually between 1/2 and
4 hr; however, in one test the Carboloy
vs. graphite seal operated satis-
factorily for 42 hours. The area of
seal contact was 1 1/2 in.‘ in each
test, and the seal contact force was
varied from 5 to 20 pounds. Similar
results were obtained when Carboloy
VS. graphite seals were tested with
MoSz and RbOH used as lubricants.
A1 though some seals showed relatively
little chattering, therewas, generally,
a marked increase in the torque
required to overcome the seal friction
as the seals heated up.
Combination Packed and Frozen Seal.
A seal consisting of a stuffing box
packed with powdered graphite in which
the slight leakage of fluoride was
frozen in the packing compression
member was operated for a period of
215 hr at temperatures from 970 t o
1500’F with system pressuresthat
varied from 16 to 37 psi. Leakage
rates were measured at various temper-
atures and pressures in an attempt to
determine the most favorable operating
conditions.
(3)P~re Carbon Company, Inc., Properties of
Pure-Bond, Bulletin No. 52. p. 5.
t4)R.
(1948).
H. Savage, J. Appl. Phys. 19. 1-10
AVERAGE LEAKAGE LEAST AMOUNT OF LEAKAGE
(g/hr) (g/hr)
1 0. 15
1 0.4
3 0.4
_I
25