MREL DATA TRAP II, Руководство по эксплуатации

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DataTrap II™ Operations Manual - Edition 5.4
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Care must be taken to select a good site for detonation and VOD recording of explosive samples. If convenient, permanent test sites may
be constructed. A pit surrounded by an earth wall suffices as a simple detonation site. A similarly protected shelter for the
DataTrap II™ Data/VOD Recorder and personnel can be constructed some distance away. The distance will depend on the amount of
explosive being detonated at one time, and if the explosives are confined (hazard from steel fragments). Ensure that the area is well
demarcated and that access is restricted.
If samples of explosives are to be detonated at an unprepared site, then the Operator must be careful when deciding upon what type of
ground the charges are to be placed. Avoid placement on ground with stones, rubble or anything that is likely to turn into a projectile.
The best surfaces are fines, sand or tailings.
If the Operator is recording large surface blasts in air and there is concern of airblast overpressure, then the DataTrap II™ Data/VOD
Recorder can be placed in a steel box and buried approximately 30 cm (1 ft.) under the ground surface to provide the best protection
from airblast overpressure.
It is always good practice to have maximum control over the time of firing of the test, therefore safety fuse initiation is not recommended.
Electric or shock tube initiation is best with the detonator either initiating the sample of explosives or initiating the primer/booster in the
explosive sample.
5.2 The Resistance Wire Technique For Measuring VOD
The DataTrap II™ Data/VOD Recorder is capable of monitoring the continuous VOD profile along the entire length of an explosives
column. The DataTrap II™ Data/VOD Recorder can measure the VOD of relatively short explosive samples such as explosive cartridges.
The DataTrap II™ Data/VOD Recorder can also measure the VOD of explosives loaded in blastholes in surface or underground blasts, in
single and multiple hole blasts. The DataTrap II™ Data/VOD Recorder provides a regulated constant excitation signal to the VOD probes
and monitors the drop in voltage across them.
The DataTrap II™ Data/VOD Recorder uses the proven continuous resistance wire technique for monitoring VODs . An MREL -qualified
probe of known linear resistance (i.e. ohm/m or ohm/ft) is placed axially in the explosive sample or explosive column. As the detonation
front of the explosive consumes the probe, the resistance of the circuit will decrease in proportion to the reduction in length of the probe.
The
DataTrap II™ Data/VOD Recorder records the resulting decrease in voltage across the VOD probe versus time.
The DAS™ Data Acquisition Suite Software automatically converts the recorded data into a graph of distance versus time for each VOD
channel utilized. The slope of this graph at any position is the VOD of the explosive at that particular position. The Software includes
menu functions that will automatically calculate and display the VOD of an explosive at any selected location in the graph. Other
5.1 Safety Considerations For Selecting An Explosive Testing Site
This Chapter provides detailed instructions on selecting a suitable site for testing
sample explosives, loading VOD PROBEROD and VOD PROBECABLE and connecting the
DataTrap II™ Data/VOD Recorder to record VODs and deck delay times.
Overview
S T O P
Contact MREL for site specific recommendations for testing samples of explosives.