Chemistry Reference
In-Depth Information
5.2 “Flash-Block” Device
A diagram of an installation used to study the kinetics of the high-temperature
decomposition of blasting powders and composite solid propellants is shown in
Fig. 5.1.
Aluminum block-heater
1
(cylinder 45 mm in diameter, 120 mm long) is equipped
with resistance thermometer
2
that is attached to its lateral surface and a heating coil
3
(the temperature control system is similar to that of installation LP-3, so the other
parts indicated in Fig. 5.2 are not listed). Sample
8
is placed onto a textolite plate
9
fixed onto lifter
10
, which is equipped with an anti-vibration buffer. In the exper-
iments with nitrocellulose samples, thermostat
5
(a sealed steel vessel with inner
channel
6
) was used to set various
T
∞
values. Heat carrier
7
(water or carbon tetra-
chloride) is supplied to the thermostat through ultrathermostat connecting pipes.
The temperature of the end of the bottom of the block is kept constant (
0
.
3
◦
C).
The sample was lifted and pressed onto the block using a load fixed onto three
threads that pass over pulleys and were connected to the lifter. The value of
t
ign
was
measured (with good accuracy) using a stop-watch with a scale interval of 0.1 s.
After sample inflammation, the kinematic unit was returned to the original position,
and the block surface was cleaned from the residue (without cooling the block, using
sandpaper wound onto a bush over cotton wool; the bush was connected to a high-
speed motor via a flexible shaft, and the sandpaper did not burn onto the block due
to the high rotation speed).
±
RR
V
R
III
V
II
II
III
Fig. 5.1
Installation schematic: block heater (
1
), resistance thermometer (
2
), heating coil (
3
), hot
thermojunction (
4
), thermostat body (
5
), thermostat channel (
6
), heat carrier (
7
), sample (
8
), tex-
tolite plate (
9
), lifter stem (
10
), lifter buffer (
11
), resistive bridge (
12
), amplifier (
13
), ballast rheo-
stat (
14
)
