5
Parr Instrument
Acid Digestion Bombs
4749 GENERAL PURPOSE
BOMB
23 mL
250 °C
1800 psig
T
his is a 23 mL, general
purpose acid digestion
bomb, similar to the
original 4745 model, but
modified with a thick-walled
Teflon Liner and a broad
flanged seal for use at tempera-
tures and pressures up to
250 °C and 1800 psig
maximum. The bomb is sealed
by tightening the cap with a hook spanner while holding the
bomb in a special fixture. Should the operator inadvertently fail
to follow the recommended operating procedures, resulting in
the development of internal pressures well above the 1800 psig
limit, a metal disc above the Teflon cover will rupture at approxi-
mately 3500 psig, releasing the charge through an opening in the
bomb cover. This safety feature, combined with its higher
temperature limit, make the 4749 bomb an excellent choice for
all general digestion purposes, and particularly for experimental
procedures in which the behavior of the reactants has not
been well established.
One of the original applications for this bomb, which
continues to be one of its principal uses, is for digesting alumina
samples at temperatures to 250 °C. For this and other difficult
digestions, Parr offers an optional tumbling ring which can be
attached to the bomb body. With this ring in place, the bomb
will roll smoothly when placed on a powered roller, thus
providing a convenient means for agitating the charge during
long digestion procedures.
Accessories such as the spanner wrench, holding fixture
and tumbling ring are not included with the bomb and must be
ordered separately.
ORDERING INFORMATION
4749
Acid digestion bomb, 23 mL
A280AC
Replacement Teflon cup with cover, 23 mL
286AC
Corrosion disc, .001”, T347SS
287AC
Rupture disc, .0025”, Inconel
264AC2
Hook spanner wrench
A285AC
Holding fixture
A284AC
Tumbling ring
Bulletin 4700
4745 GENERAL PURPOSE
BOMB
23 mL
150 °C
1200 psig
T
his is the original acid
digestion bomb intro-
duced by Parr in 1969 to
provide a Teflon lined metal
bomb of simple design and
minimum cost that can be used
safely for routine sample prepa-
ration purposes. Its wide accep-
tance over the intervening years
has proven it to be an excellent
design for general digestion procedures in which temperatures
and pressures are held below 150 °C and 1200 psig. It can be
used occasionally above 150 °C, but at elevated temperatures it
becomes increasingly difficult to maintain a tight seal.
The bomb does not have a safety rupture disc, but it is
designed so that the bottom plate will shear out and release the
charge if the bomb pressure should exceed 7000 psig. This “weak
link” design, while effective in preventing a lateral burst which
might injure a bystander, is not an adequate substitute for a
frangible rupture disc as provided in other Parr designs. For this
reason, the 4745 bomb is not recommended for experimental
procedures in which explosive pressures may be generated.
ORDERING INFORMATION
4745
Acid digestion bomb, 23 mL
A255AC
Replacement Teflon cup with cover, 23 mL
The 4744 and 4749 Bombs can be held firmly in an A285AC Holding
Fixture while tightening the cap with a 264AC2 Hook Spanner.
4749 Bomb with A284AC
Tumbling Ring
