T
he Parr Instrument Company
Technical Staff is available
to assist in the design, selection
and integration of components
for custom calorimeter sys-
tems. One such example is the
recent design of the Parr 6790
Detonation Calorimeter.
Ordinary oxygen bomb com-
bustion calorimetry is used to
measure the heat of combus-
tion or reaction of materials in oxygen or
inert atmospheres. Even for high strength
vessels, such as the Parr 1104 Oxygen
Combustion Bomb, the conditions neces-
sary to detonate small amounts of highly
reactive materials are often difficult to
achieve and can result in unpredictable
consequences. For example, the con-
ventional heat of combustion of pentae-
rythritol tetranitrate (PETN) [C
5
H
8
N
4
O
12
]
in oxygen is 1957 cal/g while the heat of
detonation in vacuum is 1490 cal/g (a 24%
difference).
Additionally, it is well known that
the degree of confinement of explosive
materials significantly influences the
released energy. For unconfined or lightly
confined charges, the released energy is
largely retained in the products. When the
charge is heavily confined, the detonation
energy, for the most part, is converted to
kinetic and internal energy of the confin-
ing case. For example, the conventional
heat of combustion of 2,4,6-trinitrotolu-
ene (TNT) in oxygen is 3590 cal/g. The
heat of detonation for TNT at a charge
density of 1.53 g/cc is 1093 cal/g and at a
charge density of 0.998 g/cc is 870 cal/g.
In contrast, an unconfined reaction yields
approximately 600 cal/g.
Precise fundamental information
about the detonation process can be
obtained by combining calorimetric and
dynamic pressure measurements. These
measurements can be used ultimately
to predict explosives performance. The
Parr Detonation Calorimeter has been
designed to aid research in this area.
Parr Instrument Company’s heat of
detonation calorimeter accepts up to a 25
g high explosive charge with a nominal
total energy release per charge of ~160
kJ. The detonation is initiated using a
small commercial EBW style detonator
incorporating 80 mg of PETN and 450 mg
of RDX with a binder. Detonators are fired
using a one-microfarad – 4000 V capaci-
tance discharge firing set. A complete
calorimetric measurement can be made
in a few hours with a precision of several
tenths of a percent. The bomb can be
optionally fitted with a high-speed pres-
sure transducer that allows the user to
gain further insight into the dynamics of
the detonation process.
Detonation Calorimeter with the
Parr Detonation Calorimeter Bomb
6790 Detonation Calorimeter
O x y g e n C o m b u s t i o n C a l o r i m e t e r s
B u l l e t i n 6 0 0 0
23
1 - 8 0 0 - 8 7 2 - 7 7 2 0
S P E C I F I C A T I O N S
Model Number:
6790
Tests per hour:
1
Operator Time Per Test:
20 Minutes
Jacket Type:
Continuously Compensated
Oxygen Fill:
Manual
Bucket Fill:
Manual
Bomb Wash:
Manual
Bomb Model Options:
A500A
Balance Communication:
USB
Printer Communication:
USB
Network Connection:
TCP/IP via Ethernet
