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The entry range is from 0 to 35bar.
The filling is monitored and if it slows down to 0.05bar per second it is terminated. This eliminates any
problem with the pressure regulator setting being a fraction lower than the target pressure. However,
when the filling pressure doesn't reach the pressure fill minimum then filling process is terminated. The
minimum limit can be adjusted by:
96
PRESS FILL MIN
The minimum filling pressure specifies the limit at which the unit stops working. It allows for slow filling
and near empty oxygen bottles. The default is 20bar, which is sufficient for avoiding oxygen starvation at
26KJ/g Samples.
Once the filling operation is complete the unit goes to the INITIAL PERIOD and monitors the pressure. If
the pressure drops by more than the FILL LEAK then a warning is displayed. Note that the pressure will
drop about 1 bar depending on the restrictor and the flow constrictions in the lid.
95
PRESS FILL LEAK
After filling the vessel with oxygen, the pressure is monitored and if it declines (leaks) by more than the
limit a warning is issued. Theoretical the pressure should be constant, but it requires approx. 1 bar to
equalise. The default setting is 1.5bar.
After the INITIAL PERIOD the sample is ignited and the MAIN PERIOD starts. The burning sample caused
a very large gas temperature rise. This pressure rise is monitored. The pressure rise depends on the
burning speed of the sample. Faster burning material have a higher peak pressure. The peak pressure
and time in milliseconds are recorded with the sample. A very high pressure can also be the result of a
large sample mass or energy content. For safety concerns the unit has two pressure limits:
A) A fixed limit of 90bar. This limit is always in effect.
B) A variable user setting limit:
87
PRESS PEAK LIMIT
The pressure peak limit (Default=70bar) is the max. pressure allowed shortly after firing when the
pressure increases proportional to the burning speed. When the pressure exceeds this limit, the event is
recorded and the operator is warned. At this point the unit is NOT shutdown. The pressure peak
checking can be disabled by entering zero.
If a limit is exceeded the vessel is deflated to a safe pressure and the main period is terminated after a
short time. The CAL3K-AP records:
The absolute pressure
The time from firing
Peak Temperature, approx. 30 seconds after firing
DDS CALORIMETERS OPERATIONS MANUAL V1.1
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2022
Digital Data Systems (Pty) Ltd.
CAL3K Advanced Bomb Calorimeters
www.ddscalorimeters.com
Website:
www.ddscalorimeters.com
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