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Back Pressure Condition
Applicable Item : Multi Cylinder Type Plug
It is better to change the injection pressure of multi function plug depending on water level between a manhole and a manhole.
There are cases when the air increases dramatically because plus itself is moved back by act (pressure) of water against the plug.
At this time the plug could become dangerous, so it is recommended to inject air with confirming reference table.
It is advisable to inject about 70% of plug air pressure at the full level water. (when blocking water for D450~1000 or more for more than two hours)
| Water Level inside the Pipe Diameter | |||||||||
| Water Level | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% | 100% |
| PLUG Air Injection Pressure(kgf/㎠) | |||||||||
| Standard | 100% | 100% | 100% | 100% | 100%-90% | 90% | 80% | 70% | 70%-60% |
| 80-150 | 1.5 | 1.5 | 1.5 | 1.5 | 1.4 | 1.4 | 1.3 | 1.2 | 1.0 |
| 100-200 | 1.5 | 1.5 | 1.5 | 1.5 | 1.4 | 1.4 | 1.3 | 1.2 | 1.0 |
| 150-300 | 1.5 | 1.5 | 1.5 | 1.5 | 1.4 | 1.4 | 1.3 | 1.2 | 1.0 |
| 200-500 | 1.5 | 1.5 | 1.5 | 1.5 | 1.4 | 1.3 | 1.3 | 1.2 | 1.0 |
| 300-600 | 1.2 | 1.2 | 1.2 | 1.2 | 1.2 | 1.0 | 1.0 | 0.9 | 0.8 |
| 450-1000 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 0.9 | 0.8 | 0.7 | 0.7 |
| 600-1200 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 0.9 | 0.8 | 0.7 | 0.7 |
| 800-1500 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 0.9 | 0.8 | 0.7 | 0.7 |
| 1000-2000 | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 | 0.7 | 0.7 | 0.6 |
