Parr Instrument 6100 - Manual (Page 23)

Operating Instructions
6100 5
w w w . p a r r i n s t . c o m 21
Capsules should be monitored for wear. Do not use
the capsule if the wall or base thickness is less than
0.025”.
New capsules are heated in a muffle furnace at 500 ºC
for 24 hours to develop this protective coating
uniformly on all surfaces. This treatment should be
repeated after a capsule has been polished with an
abrasive to remove any ash or other surface depos-
its. Heating in a muffle is also a good way to destroy
any traces of carbon or combustible matter which
might remain in the capsule from a previous test.
Note: After heating, place the capsules in
a clean container and handle them only
with forceps when they are removed to be
weighed on an analytical balance.
Foodstuffs and Cellulosic Materials
Fibrous and fluffy materials generally require one
of three modes of controlling the burn rate. Fibrous
materials do not pelletize readily and generally
require either moisture content or a combustion aid
such as mineral oil to retard the burn rate and avoid
development of high pressures.
Partial drying may be necessary if the moisture con-
tent is too high to obtain ignition, but if the sample
is heat sensitive and cannot be dried, a water
soluble combustion aid such as ethylene glycol can
be added to promote ignition.
Coarse Samples
In most cases it may be necessary to burn coarse
samples without size reduction since grinding or
drying may introduce unwanted changes. There is
no objection to this if the coarse sample will ignite
and burn completely.
Whole wheat grains and coarse charcoal chunks are
typical of materials which will burn satisfactorily
without grinding and without additives or a special
procedure.
Corrosive Samples
The 1108P Oxygen Combustion Vessel is made of a
corrosion resistant alloy designed to withstand the
corrosive mixture of sulfuric and nitric acids pro-
duced in normal fuel testing operations. Samples
containing chlorine and particular samples contain-
ing more than 20 mg of chlorine samples with high
sulfur contents will greatly accelerate corrosion of
the bomb. An alternate 1108PCL vessel is available
constructed of an alloy selected to specifically resist
the corrosive effects of samples with high chlorine
or other halogens.
While no material will offer complete corrosion
resistance to these samples, the 1108PCL vessel
offers significantly enhanced corrosion resistance
for this service.
Figure 5-3
43A6 Combustion Capsule with
Adhesive Tape Seal
Figure 5-2
3601 Gelatin Capsules
Figure 5-4
43AS Combustion Capsules