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Long delay detonators range from delay numbers 1-10 with intervals of 500 ms or 0.5 sec, between successive delays. They are also called half second delays . In both Delays i.e. SDD LDD Delay No.is embossed at the bottom of the shell for easy identification and delay number with a tag is put to one of the lead wires for identification. The flame by the fuse head ignites the pyrotechnic delay element which conveys flame to the ASA, which in turn detonates the PETN charge. The delay timings are achieved by inserting an appropriate delay element over ASA in the filled shell. Delay element is of lead filled with pyrotechnic composition. The spit of fire from fusehead is adequate for firing Delay element composition which subsequently detonates the detonator.
| Shell material | Aluminum |
| Shell length | 7.2+/-0.02 mm |
| Shell length / Nominal Time: |
| Delay No. | Shell Length (mm) | Short Delays (ms) | Long Delays (sec) |
|---|---|---|---|
| 1 | 47 | Instantaneous | Instantaneous |
| 2 | 57 | 25 | 0.5 |
| 3 | 59 | 50 | 1.0 |
| 3 | 61 | 75 | 1.5 |
| 4 | 64 | 100 | 2.0 |
| 5 | 66 | 125 | 2.5 |
| 6 | 68 | 150 | 3.0 |
| 7 | 70 | 200 | 3.5 |
| 8 | 72 | 250 | 4.0 |
| 9 | 74 | 325 | 4.5 |
| 10 | 77 | 400 | 5.0 |
| Bare Wire Diameter | 0.46-0.48 mm |
| Lead wire colour | green/green |
| Coated Lead wire diameter | 0.8-1.0 mm |
| Head wire resistance | 0.7 ohms/m |
| Lead wire length | standard length of 2,3,4,5m |
| Fuse head characteristics: Fuse head resistance | 1.6-2.4 ohms |
| Firing impulse | 3.2 milli watt sec/ohm |
| Firing current | 1.2 amps DC current, 0.8 ampere DC for single current |
| No fire current | 0.18 amps applied for 300 seconds |
| Packing material | Corrugated box |
| Packing per box: |
| Lead wire length(metres) | Quantity (nos.) |
|---|---|
| 2.0 | 1000 |
| 3.0 | 1000 |
| 4.0 | 500 |
| 5.0 | 500 |
| 6.0 | 500 |
Delay Electric Detonators are used to achieve controlled blasting and good fragmentation which enables easy handling and providing good ground vibration, controlled noise and fly rocks. Long delays are used in underground mining for driving shafts and tunnel, sinking shafts, trenching etc. The longer delay period gives sufficient rock movement before firing the consecutive shots.
25 detonators are crimped and formed into a bundle. Two such bundles are wrapped in craft paper to make a packet of 50 nos. As per the length of the wire, the packets are kept in a corrugated box.
| Class | 6 |
| Division | 3 |