Manta 5000ST Freeflow - Filter Failure
Incident Date
1990-04-04
Incident Description
At a point 150m from the surface a 1988 model Manta 5000ST DIN valve started to free-flow in an excessive fashion. The cylinder tap was closed and an exit made on the alternate supply. On stripping the valve it was discovered that the fibrous first stage filter had ruptured and blown fibres across both the first stage and second stage valve seats. Further investigation recreated this failure mode when the following two conditions were both met; 1) the valve seat was wet and 2) the cylinder valve was opened quickly.
Lessons Learned
When diving with a Manta 5000ST DIN (or any DV with a fibrous 1st stage filter) it is important to keep the filter dry. If the filter becomes wet then the valve must be pressurised very slowly. If possible fit a sintered filter to the unit or use valves with sintered filters as standard.
| Factors |
|
| Line Management |
Negligible |
| Gas Management |
Negligible |
| Equipment Management |
Minor |
| Equipment Failure |
Major |
| Training |
Negligible |
| Medical |
Negligible |
| Planning |
Negligible |
| Procedural Error |
Negligible |
| Cave Environment |
Negligible |
| Weather |
Negligible |
| Other Factor |
Negligible |
